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Oxyfluoride core silica-based optical fiber with intrinsically low nonlinearities for high energy laser applications
M. Cavillon, C. J. Kucera, T. W. Hawkins, A. F. J. Runge, A. C. Peacock, Senior Member, IEEE, P. D. Dragic, Member, IEEE, J. Ballato, Fellow IEEE
Abstract A few-moded silica-based optical fiber fabricated from core materials that possess intrinsically low optical nonlinearities is reported. Specifically, the 8 m core, 125 m cladding diameter silicate fiber was composed of a strontium alum i n o s i l i c a t e o x y f l u o r i d e c o r e w i t h a f u s e d s i l i c a c l a d d i n g a n d w a s f a b r i c a t e d u s i n g t h e m o l t e n c o r e m e t h o d . R e l a t i v e t o c o n v e n t i o n a l o p t i c a l f i b e r s , r e d u c t i o n s o f <"6 . 3 d B i n B r i l l o u i n g a i n c o e f f i c i e n t ( g B ) , <"0 . 9 d B i n R a m a n g a i n c o e f f i c i e n t ( g R ) , a n d <"2 . 2 d B i n t h e r m o - o p t i c c o e f f i c i e n t ( T O C ) w e r e r e a l i z e d a s w a s a s i l i c a - l i k e n o n l i n e a r r e f r a c t i v e i n d e x ( n 2 ) w i t h a v a l u e o f <"3 x 1 0 - 2 0 m 2 / W . T h e r o l e o f e a c h c o r e m a t e r i a l c o n s t i t u e n t o n p a r a m e t e r s t h a t d r i v e o p t i c a l n o n l i n e a r i t i e s i s d i s c u s s e d t o p r o v i d e a m a terials solution route for low nonlinearity fiber systems. Materially addressing optical nonlinearities represents a simpler and more effective approach to mitigating power-scaling limits in high energy fiber laser systems compared to the geometric approaches employed using microstructured fibers.
Index TermsHigh energy lasers, optical fiber, stimulated Brillouin scattering, stimulated Raman scattering, thermo-optic coefficient, nonlinear refractive index
INTRODUCTION
O
PTICAL nonlinearities serve as limitations to continued optical power scaling in high energy fiber-based laser systems. Paramount amongst these parasitic phenomena are stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and nonlinear refractive index, n2, related wave-mixing phenomena (e.g., four-wave mixing, FWM, and self-phase modulation, SPM) ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1364/OE.16.013240", "ISBN" : "1094-4087", "ISSN" : "1094-4087", "PMID" : "18711562", "abstract" : "We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well as fiber mode field diameter (MFD) restrictions. We derive new general relationships based upon practical considerations. Our analysis shows that if the fiber's MFD could be increased arbitrarily, 36 kW of power could be obtained with diffraction-limited quality from a fiber laser or amplifier. This power limit is determined by thermal and non-linear limits that combine to prevent further power scaling, irrespective of increases in mode size. However, limits to the scaling of the MFD may restrict fiber lasers to lower output powers.", "author" : [ { "dropping-particle" : "", "family" : "Dawson", "given" : "Jay W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Messerly", "given" : "Michael J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Beach", "given" : "Raymond J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Shverdin", "given" : "Miroslav Y", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stappaerts", "given" : "Eddy A", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sridharan", "given" : "Arun K", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pax", "given" : "Paul H", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Heebner", "given" : "John E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Siders", "given" : "Craig W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Barty", "given" : "C P J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics express", "id" : "ITEM-1", "issue" : "17", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "13240-13266", "title" : "Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power.", "type" : "article-journal", "volume" : "16" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=0a8927b0-0014-4f38-bc56-37c7f97e177a" ] } ], "mendeley" : { "formattedCitation" : "[1]", "plainTextFormattedCitation" : "[1]", "previouslyFormattedCitation" : "[1]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[1]. In order to combat these performance limitations, fiber designers have developed ever-more complex structures that aim to spread the propagating mode out over a larger cross-sectional area so as to reduce the power density in the fiber below the threshold power for each parasitic effect. Such large mode area (LMA) fibers are often designed to behave as effectively single mode waveguides by controlling the losses associated with the higher order modes. Based on their inherently and inextricably multimode nature, such designs introduce additional parasitic phenomena, such as the thermally mediated Transverse Mode Instability (TMI) where, at some threshold power, the beam modal distribution randomizes and becomes dynamic. TMI diminishes beam quality and is presently the main cause of power scaling restrictions in high energy laser applications ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1364/OE.19.010180", "ISSN" : "1094-4087", "PMID" : "21643276", "abstract" : "For powers exceeding a sharp threshold in the vicinity of several hundred watts the beam quality from some narrow bandwidth fiber amplifiers is severely degraded. We show that this can be caused by transverse thermal gradients induced by the amplification process.", "author" : [ { "dropping-particle" : "V", "family" : "Smith", "given" : "Arlee", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "Jesse J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics express", "id" : "ITEM-1", "issue" : "11", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "10180-10192", "title" : "Mode instability in high power fiber amplifiers.", "type" : "article-journal", "volume" : "19" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=ac376e11-4a0f-436c-9cc1-c9ebfa432cae" ] } ], "mendeley" : { "formattedCitation" : "[2]", "plainTextFormattedCitation" : "[2]", "previouslyFormattedCitation" : "[2]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[2].
This paper presents results based on a second approach to mitigating nonlinear limitations in optical fiber lasers; namely attacking such nonlinearities at their fundamental origin the material through which the light propagates. Though less well studied within the fiber laser community, such a materials approach offers a more powerful yet simpler and more scalable way to address nonlinearities in comparison to the greater complexity and cost of sophisticated fiber designs ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "abstract" : "From a materials perspective optical fibers are victims of their own success. The advent of the laser, 50 yr ago, coupled with an insatiable demand for information enabled by light-based communications, ushered in a golden age of glass science and engineering. It is somewhat ironic that the staggering ubiquity of information today, which is carried globally and almost instantaneously via optical fibers, is enabled largely by one material\u2014silica\u2014into which only a few components are added. The richness of the Periodic Table has largely been forgotten. The purpose of this study was to rethink the materials that can be used to make commercially relevant optical fibers and describe the extraordinary properties, with stimulated Brillouin scattering being the primary exemplar, of fibers made from otherwise ordinary materials. In particular, this study focuses on the use of the molten core approach to optical fiber fabrication and the novel yet practical fibers that can be produced. This study is purposely provocative and aims to reassert the centrality (and simplicity and beauty) of glass science as the best approach to meet future challenges for high-performance optical fibers.", "author" : [ { "dropping-particle" : "", "family" : "P. Dragic", "given" : "J. Ballato", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of the American Ceramic Society", "id" : "ITEM-1", "issue" : "9", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "2675-2692", "title" : "Rethinking Optical Fiber: New Demands, Old Glasses", "type" : "article-journal", "volume" : "96" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=f6205d5f-2954-4c2d-885e-8e834a52279b" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.3390/ma7064411", "ISSN" : "19961944", "abstract" : "Optical fibers, the enablers of the Internet, are being used in an ever more diverse array of applications. Many of the rapidly growing deployments of fibers are in high-power and, particularly, high power-per-unit-bandwidth systems where well-known optical nonlinearities have historically not been especially consequential in limiting overall performance. Today, however, nominally weak effects, most notably stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) are among the principal phenomena restricting continued scaling to higher optical power levels. In order to address these limitations, the optical fiber community has focused dominantly on geometry-related solutions such as large mode area (LMA) designs. Since such scattering, and all other linear and nonlinear optical phenomena including higher order mode instability (HOMI), are fundamentally materials-based in origin, this paper unapologetically advocates material solutions to present and future performance limitations. As such, this paper represents a \u2018call to arms\u2019 for material scientists and engineers to engage in this opportunity to drive the future development of optical fibers that address many of the grand engineering challenges of our day.", "author" : [ { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Materials", "id" : "ITEM-2", "issue" : "6", "issued" : { "date-parts" : [ [ "2014" ] ] }, "page" : "4411-4430", "title" : "Materials development for next generation optical fiber", "type" : "article-journal", "volume" : "7" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=852d40cc-96a1-4580-be48-b53f0d1613c6" ] } ], "mendeley" : { "formattedCitation" : "[3], [4]", "manualFormatting" : "[3], [4]", "plainTextFormattedCitation" : "[3], [4]", "previouslyFormattedCitation" : "[3], [4]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[3], [4]. As an example, it is known that the magnitude of stimulated Brillouin scattering is proportional to the Brillouin gain coefficient, gB, which is related to the mater i a l d e n s i t y ( ) , r e f r a c t i v e i n d e x ( n ) , a c o u s t i c v e l o c i t y ( V a ) , B r i l l o u i n s p e c t r a l l i n e w i d t h ( ) , a n d t h e P o c k e l s p h o t o e l a s t i c c o e f f i c i e n t ( p 1 2 ) . T h e l a t t e r p a r a m e t e r , p 1 2 , i s o f p a r t i c u l a r i n t e r e s t s i n c e i t i s t h e o n l y f a c t o r i n d e t e r m i n i n g g B t h a t c a n t ake a null value thus permitting, in a suitable material, the complete eradication of SBS. Using this approach, nearly 20 dB suppression in SBS has been achieved using simple core/cladding optical fibers possessing intrinsically low photoelasticity ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/nphoton.2012.182", "ISBN" : "1749-4885", "ISSN" : "1749-4885", "abstract" : "As performance demands continue to grow, many optical fibre systems are operating at progressively higher power levels. However, Brillouin scattering restricts continued power scaling in narrow-linewidth systems. Optical fibres with engineered Brillouin properties that are manufactured using industry-accepted methods would be of great practical benefit. Here, we show all-glass optical fibres derived from sapphire that have alumina concentrations of up to \u223c55 mol%, which is considerably greater than conventionally possible and enables a series of useful properties. Specifically, a Brillouin gain coefficient of 3.1310\u201313mW\u20131, a value nearly 100 times lower than commercial fibre, was measured for a fibre with an average alumina concentration of 54 mol%. Furthermore, a fibre with \u223c38 mol% alumina was found to be athermal, with a Brillouin frequency that was insensitive to changes in temperature. Such optical fibres may be beneficial in realizing enhanced telecommunication, sensor and high-energy laser systems.", "author" : [ { "dropping-particle" : "", "family" : "Dragic", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Foy", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature Photonics", "id" : "ITEM-1", "issue" : "9", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "629-635", "title" : "Sapphire-derived all-glass optical fibres", "type" : "article-journal", "volume" : "6" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=01d80761-3558-4816-aa5c-98f29bc6f6c2" ] } ], "mendeley" : { "formattedCitation" : "[5]", "plainTextFormattedCitation" : "[5]", "previouslyFormattedCitation" : "[5]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[5]. Raman scattering is an intrinsic material property that can also be reduced using intrinsically low Raman gain materials, coupled with a fabrication process with rapid quench rates that promote a more disordered core glass. This approach has led to a reduction of <"3 d B i n R a m a n g a i n c o e f f i c i e n t ( g R ) r e l a t i v e t o s i l i c a A D D I N C S L _ C I T A T I O N { " c i t a t i o n I t e m s " : [ { " i d " : " I T E M - 1 " , " i t e m D a t a " : { " D O I " : " 1 0 . 1 0 4 9 / e l . 2 0 1 3 . 1 3 8 6 " , " I S B N " : " 0 0 1 3 - 5 1 9 4 " , " I S S N " : " 0 0 1 3 5 1 9 4 " , " a b s t r a c t " : " F o r t h e f i r s t t i m e , R a m a n g a i n s p e c tra are measured for three all-glass Yb:YAG crystal-derived optical fibres. It is shown that fibres derived from YAG have a reduced Raman gain relative to that of pure silica, partly because of a significant broadening of the silica Raman lines, and also partly because of yttria and alumina possessing a lower gain than that of silica. Such a designer-materials approach for suppression of stimulated Raman scattering can enable future high-energy and high-peak-power fibre laser systems.", "author" : [ { "dropping-particle" : "", "family" : "Dragic", "given" : "P D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Electronics Letters", "id" : "ITEM-1", "issue" : "14", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "895-897", "title" : "Characterisation of Raman gain spectra in Yb:YAG-derived optical fibres", "type" : "article-journal", "volume" : "49" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=d177a3e1-fb55-4e92-aefd-e7238fbf3aa9" ] } ], "mendeley" : { "formattedCitation" : "[6]", "plainTextFormattedCitation" : "[6]", "previouslyFormattedCitation" : "[6]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[6]. Finally, thermal effects such as TMI or thermal lensing (TL) are directly proportional to the thermo-optic coefficient (TOC) ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Dong", "given" : "Liang", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics express", "id" : "ITEM-1", "issue" : "3", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "915-918", "title" : "Stimulated thermal Rayleigh scattering in optical fibers", "type" : "article-journal", "volume" : "21" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=c385e544-47f6-47fb-b9e8-82cdf64e44b5" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1364/OE.19.010180", "ISSN" : "1094-4087", "PMID" : "21643276", "abstract" : "For powers exceeding a sharp threshold in the vicinity of several hundred watts the beam quality from some narrow bandwidth fiber amplifiers is severely degraded. We show that this can be caused by transverse thermal gradients induced by the amplification process.", "author" : [ { "dropping-particle" : "V", "family" : "Smith", "given" : "Arlee", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Smith", "given" : "Jesse J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics express", "id" : "ITEM-2", "issue" : "11", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "10180-10192", "title" : "Mode instability in high power fiber amplifiers.", "type" : "article-journal", "volume" : "19" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=ac376e11-4a0f-436c-9cc1-c9ebfa432cae" ] }, { "id" : "ITEM-3", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Dong", "given" : "Liang", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics express", "id" : "ITEM-3", "issue" : "17", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "19841-19852", "title" : "Thermal lensing in optical fibers", "type" : "article-journal", "volume" : "24" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=da43c6f5-c52f-44df-b6e9-cf45bf1a64e8" ] } ], "mendeley" : { "formattedCitation" : "[2], [7], [8]", "plainTextFormattedCitation" : "[2], [7], [8]", "previouslyFormattedCitation" : "[2], [7], [8]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[2], [7], [8]. Therefore, a reduction, and at best suppression, of TL is expected with low-TOC materials. To date, however, to the best of the Authors knowledge, each of these reductions has been achieved individually in a fiber; i.e., there is no report of simultaneous reductions to SBS, SRS, and TOC in a single fiber from a common core material. This is the purpose of this work.
In order to materially attack each of these nonlinearities collectively, a silica cladding and silicate core glass optical fiber in the ternary strontium fluoride (SrF2) alumina (Al2O3) silica (SiO2) precursor system was fabricated. Alumina and alkaline earth oxides in silicates are known to exhibit intrinsically low gB values ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1038/nphoton.2012.182", "ISBN" : "1749-4885", "ISSN" : "1749-4885", "abstract" : "As performance demands continue to grow, many optical fibre systems are operating at progressively higher power levels. However, Brillouin scattering restricts continued power scaling in narrow-linewidth systems. Optical fibres with engineered Brillouin properties that are manufactured using industry-accepted methods would be of great practical benefit. Here, we show all-glass optical fibres derived from sapphire that have alumina concentrations of up to \u223c55 mol%, which is considerably greater than conventionally possible and enables a series of useful properties. Specifically, a Brillouin gain coefficient of 3.1310\u201313mW\u20131, a value nearly 100 times lower than commercial fibre, was measured for a fibre with an average alumina concentration of 54 mol%. Furthermore, a fibre with \u223c38 mol% alumina was found to be athermal, with a Brillouin frequency that was insensitive to changes in temperature. Such optical fibres may be beneficial in realizing enhanced telecommunication, sensor and high-energy laser systems.", "author" : [ { "dropping-particle" : "", "family" : "Dragic", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "T.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Foy", "given" : "P.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Morris", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Nature Photonics", "id" : "ITEM-1", "issue" : "9", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "629-635", "title" : "Sapphire-derived all-glass optical fibres", "type" : "article-journal", "volume" : "6" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=01d80761-3558-4816-aa5c-98f29bc6f6c2" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1364/OE.21.010924", "ISSN" : "1094-4087", "PMID" : "23669949", "abstract" : "Presented here for the first time to the best of our knowledge is a\\ndetailed Brillouin spectroscopic study of novel, highly-BaO-doped silica\\nglass optical fibers. The fibers were fabricated utilizing a molten-core\\nmethod and exhibited baria (BaO) concentrations up to 18.4 mole %.\\nPhysical characteristics such as mass density, acoustic velocity,\\nviscoelastic damping, and refractive index are determined for the baria\\ncomponent of the bariosilicate system. It is found that, of each of\\nthese parameters, only the acoustic velocity is less than that of pure\\nsilica. The effect of temperature and strain on the acoustic velocity\\nalso is determined by utilizing estimates of the strain-and thermo-optic\\ncoefficients. The dependencies are found to have signs opposite to those\\nof silica, thus suggesting both Brillouin-frequency a-thermal and\\na-tensic binary compositions. Via the estimate of the strain-optic\\ncoefficient and data found in the literature, the Pockels' photoelastic\\nconstant p(12) is estimated, and both a calculation and measured\\nestimate of the Brillouin gain versus baria content are presented. Such\\nnovel fibers incorporating the unique properties of baria could be of\\ngreat utility for narrow linewidth fiber lasers, high power passive\\ncomponents (such as couplers and combiners), and Brillouin-based sensor\\nsystems. (C) 2013 Optical Society of America", "author" : [ { "dropping-particle" : "", "family" : "Dragic", "given" : "P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "C", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Guerrier", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "T", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optics Express", "id" : "ITEM-2", "issue" : "9", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "10924-10941", "title" : "Brillouin spectroscopy of a novel baria-doped silica glass optical fiber", "type" : "article-journal", "volume" : "21" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=d21ea446-b193-40ea-8f7d-b19a28f20e07" ] }, { "id" : "ITEM-3", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Cavillon", "given" : "Maxime", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "Joshua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "Courtney J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ryan", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tuggle", "given" : "Matthew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Maxwell", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "Thomas Wade", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-3", "issue" : "6", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "1435-1441", "title" : "Brillouin Properties of a Novel Strontium Aluminosilicate Glass Optical Fiber", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=e7b75119-034c-474c-a211-ad3f3383869a" ] } ], "mendeley" : { "formattedCitation" : "[5], [9], [10]", "plainTextFormattedCitation" : "[5], [9], [10]", "previouslyFormattedCitation" : "[5], [9], [10]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[5], [9], [10] and the multicomponent and rapidly quenched nature of molten-core-derived fibers yields a reduction in gR. Further, the introduction of fluorine into silicate glasses (in this case through the SrF2) lessens the linear and nonlinear refractive indices ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1364/AO.22.003102", "ISSN" : "0003-6935", "PMID" : "18200161", "abstract" : "Refractive index dispersion has been determined for fluorine doped fused silica containing 1 and 2% fluorine. Addition of fluorine is found to reduce the refractive index and material dispersion. Fibers modeled for minimization of modal dispersion having fused silica cores and fluorine doped silica cladding show a strong composition dependence of the optimum refractive index profile. Comparison of results with those in the literature based on N.A. vs \u03bb measurements reveal minor discrepancies probably due to the drawing process.", "author" : [ { "dropping-particle" : "", "family" : "Fleming", "given" : "J W", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wood", "given" : "D L", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Applied optics", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "1983" ] ] }, "page" : "3102", "title" : "Refractive index dispersion and related properties in fluorine doped silica.", "type" : "article-journal", "volume" : "22" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=7984c489-2cc7-481c-8761-8be7e965cd5b" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/0025-5408(86)90110-8", "ISSN" : "00255408", "abstract" : "Experimental data on the density, the refractive index and the material dispersion derived therefrom are presented for fluorine doped PCVD- (plasma activated chemical vapour deposition-) silica. Both density and refractive index decrease linearly with increasing doping concentration. Comparison of the refractive index depression in PCVD glass and data published for F-doped glasses prepared by other techniques reveal some discrepancies. The influence of small amounts of chlorine in the silica network on the refractive index and on the dispersion is also considered. ?? 1986.", "author" : [ { "dropping-particle" : "", "family" : "Wehr", "given" : "H.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wiechert", "given" : "D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Materials Research Bulletin", "id" : "ITEM-2", "issue" : "5", "issued" : { "date-parts" : [ [ "1986" ] ] }, "page" : "559-566", "title" : "Refractive index and density of fluorine doped silica prepared by the PCVD process", "type" : "article-journal", "volume" : "21" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=d55eeed4-57b8-4a3e-b14b-533ab4e0bb6c" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1109/68.992588", "ISSN" : "10411135", "abstract" : "We describe the dopant dependence of the effective nonlinear refractive index n2eff in {GeO2-} or F-doped core fibers theoretically and experimentally. We show that the dopant dependence of the nonlinear refractive index n2 of F-doped bulk glass is the inverse of that of {GeO2-doped} bulk glass. We also show that the effective nonlinear refractive index n2eff in F-doped core fibers, estimated by using the dopant content dependence of n2, is in good agreement with our experimental results. Moreover, we confirm that n2eff in an optical fiber strongly depends on the refractive index profile of its core", "author" : [ { "dropping-particle" : "", "family" : "Nakajima", "given" : "Kazuhide", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ohashi", "given" : "Masaharu", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "IEEE Photonics Technology Letters", "id" : "ITEM-3", "issue" : "4", "issued" : { "date-parts" : [ [ "2002" ] ] }, "page" : "492-494", "title" : "Dopant dependence of effective nonlinear refractive index in GeO2- and F-doped core single-mode fibers", "type" : "article-journal", "volume" : "14" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=b58062b2-e976-4f6d-b27e-ec5e01aa2a82" ] } ], "mendeley" : { "formattedCitation" : "[11]\u2013[13]", "plainTextFormattedCitation" : "[11]\u2013[13]", "previouslyFormattedCitation" : "[11]\u2013[13]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[11][13], making the fibers fewer-moded and possibly reducing wave-mixing phenomena through of the reduction in n2. Lowering the TOC can be achieved through the introduction of materials with reduced or negative TOC values, such as the alkaline earth fluoride family ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1201/9781420050196", "ISBN" : "0849335124", "ISSN" : "978-0824746131", "abstract" : "For years scientists turned to the CRC Handbook of Laser Science & Technology for reliable data on optical materials. Out of print for several years, that standard-setting work now has a successor: the Handbook of Optical Materials. This new handbook is an authoritative compilation of the physical properties of materials used in all types of lasers and optical systems. In it, scientist, author, and editor Dr. Marvin J. Weber provides extensive data tabulations and references for the most important optical materials, including crystals, glasses, polymers, metals, liquids, and gases. The properties detailed include both linear and nonlinear optical properties, mechanical properties, thermal properties together with many additional special properties, such as electro-, magneto-, and elasto-optic properties. Using a minimum of narration and logically organized by material properties, the handbook's unique presentation simplifies the process of comparing different materials for their suitability in particular applications. Appendices furnish a wealth of other useful information, including lists of the many abbreviations and acronyms that proliferate in this field. The Handbook of Optical Materials is simply the most complete one-stop source available for materials data essential to lasers and optical systems.", "author" : [ { "dropping-particle" : "", "family" : "Weber", "given" : "Marvin J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optical Materials", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2003" ] ] }, "number-of-pages" : "512", "publisher" : "CRC Press", "title" : "Handbook of optical materials", "type" : "book" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=3025818b-e72c-4021-8c40-449332637f9b" ] } ], "mendeley" : { "formattedCitation" : "[14]", "plainTextFormattedCitation" : "[14]", "previouslyFormattedCitation" : "[14]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[14] and, specifically, SrF2 as employed here in a silica matrix. Further, alumina plays a crucial role in glass formation since it prevents the well-known phase separation exhibited in binary alkaline earth silicates ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1016/0022-3093(89)90437-7", "ISSN" : "00223093", "PMID" : "5799", "abstract" : "Phase separation of silicate melts and glasses is a well documented phenomenon. Its origin, however, has remained unclear. A review of previous observations indicates that coulombic forces, and therefore ionic interaction, play an important role. By using Debye-H??ckel electrolyte theory, which treats ionic interaction, critical temperatures for the alkali and alkaline earth silicates were calculated. The theoretically predicted values are in close agreement with experimental data. ?? 1989.", "author" : [ { "dropping-particle" : "", "family" : "McGahay", "given" : "V.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tomozawa", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Non-Crystalline Solids", "id" : "ITEM-1", "issue" : "1", "issued" : { "date-parts" : [ [ "1989" ] ] }, "page" : "27-34", "title" : "The origin of phase separation in silicate melts and glasses", "type" : "article-journal", "volume" : "109" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=a0c4ab25-3090-4877-a9a7-af70201813ca" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.jnoncrysol.2008.01.005", "ISSN" : "00223093", "abstract" : "The immiscibility boundary and the critical point of SiO2-Nd2O3 system glass were determined as a function of Al2O3 addition. The critical temperature of the immiscibility boundary was observed to decrease with the addition of Al2O3. Using the regular solution model, the observed decrease of the immiscibility boundary was directly related to the decrease of the concentration fluctuation of Nd2O3 in SiO2. It is concluded that the Al2O3 addition to Nd2O3 containing silica glass is beneficial in decreasing the concentration quenching effect, deterioration of the optical efficiency due to clustering of rare earth element, because Al2O3 addition diminishes the concentration fluctuation of Nd2O3 in silica glass. ?? 2008.", "author" : [ { "dropping-particle" : "", "family" : "Hatta", "given" : "B.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tomozawa", "given" : "M.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Non-Crystalline Solids", "id" : "ITEM-2", "issue" : "27", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "3184-3193", "title" : "Effect of Al2O3 on phase separation of SiO2-Nd2O3 glasses", "type" : "article-journal", "volume" : "354" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=ac409d77-3c0a-42c7-91ef-efa1afad7651" ] } ], "mendeley" : { "formattedCitation" : "[15], [16]", "plainTextFormattedCitation" : "[15], [16]", "previouslyFormattedCitation" : "[15], [16]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[15], [16]. The use of a silicate core and a silica cladding has the added advantage of providing high strength and enhanced thermomechanical stability as is critical to the fieldability of such a fiber.
EXPERIMENTAL PROCEDURE
Fiber fabrication
The fiber was fabricated using the molten core method ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1364/AO.34.006848", "ISSN" : "0003-6935", "PMID" : "21060544", "abstract" : "The Faraday effect provides a mechanism for achieving unidirectional light propagation in optical isolators; however, miniaturization requires large Verdet constants. High rare-earth content glasses produce suitably large Verdet values, but intrinsic fabrication problems remain. The novel powder-intube method, or a single-draw rod-in-tube method, obviates these difficulties. The powder-in-tube method was used to make silica-clad optical fibers with a high terbium oxide content aluminosilicate core. Core diameters of 2.4 \u00b5m were achieved in 125-\u00b5m-diameter fibers, with a numerical aperture of 0.35 and a Verdet constant of -20.0 rad/(T m) at 1.06 \u00b5m. This value is greater than 50% for crystals found in current isolator systems. This development could lead to all-fiber isolators of dramatically lower cost and ease of fabrication compared with their crystalline competitors.", "author" : [ { "dropping-particle" : "", "family" : "Ballato", "given" : "J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Snitzer", "given" : "E", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Applied optics", "id" : "ITEM-1", "issue" : "30", "issued" : { "date-parts" : [ [ "1995" ] ] }, "page" : "6848-54", "title" : "Fabrication of fibers with high rare-earth concentrations for Faraday isolator applications.", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=f9712671-7446-4cc4-8442-ad4b53f2c2e9" ] } ], "mendeley" : { "formattedCitation" : "[17]", "plainTextFormattedCitation" : "[17]", "previouslyFormattedCitation" : "[17]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[17]. Briefly, a mixture of high purity commercially available SrF2 and Al2O3 powders (Alfa Aesar; Al2O3, 5- p h a s e : 9 9 . 9 9 7 % p u r i t y , S r F 2 : 9 9 . 9 9 % p u r i t y ) w a s m i x e d a n d i n s e r t e d i n t o a p u r e s i l i c a c a p i l l a r y t u b e o f 3 m m i n n e r a n d 3 0 m m o u t e r d i a m e t e r . T h i s p r e f o r m w a s d r a w n a t a t e m p e r a t u r e o f a b o u t 2 0 0 0 C s u c h t h a t t h e p r e c u r s o r c o r e m a t e r i a l s m e l t , a s i s c h a racteristic of the molten core method. The preform then was drawn directly into a fiber and the molten core is quenched as the fiber cools and forms a glassy state facilitated by the high cooling rates (>2000 C/s). Additional details on the fabrication method can be found in ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "abstract" : "From a materials perspective optical fibers are victims of their own success. The advent of the laser, 50 yr ago, coupled with an insatiable demand for information enabled by light-based communications, ushered in a golden age of glass science and engineering. It is somewhat ironic that the staggering ubiquity of information today, which is carried globally and almost instantaneously via optical fibers, is enabled largely by one material\u2014silica\u2014into which only a few components are added. The richness of the Periodic Table has largely been forgotten. The purpose of this study was to rethink the materials that can be used to make commercially relevant optical fibers and describe the extraordinary properties, with stimulated Brillouin scattering being the primary exemplar, of fibers made from otherwise ordinary materials. In particular, this study focuses on the use of the molten core approach to optical fiber fabrication and the novel yet practical fibers that can be produced. This study is purposely provocative and aims to reassert the centrality (and simplicity and beauty) of glass science as the best approach to meet future challenges for high-performance optical fibers.", "author" : [ { "dropping-particle" : "", "family" : "P. Dragic", "given" : "J. Ballato", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of the American Ceramic Society", "id" : "ITEM-1", "issue" : "9", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "2675-2692", "title" : "Rethinking Optical Fiber: New Demands, Old Glasses", "type" : "article-journal", "volume" : "96" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=f6205d5f-2954-4c2d-885e-8e834a52279b" ] }, { "id" : "ITEM-2", "itemData" : { "ISSN" : "00027812", "author" : [ { "dropping-particle" : "", "family" : "Morris", "given" : "By Stephanie", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "American Ceramic Society Bulletin", "id" : "ITEM-2", "issue" : "4", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "24-29", "title" : "Molten-core fabrication of novel optical fibers", "type" : "article-journal", "volume" : "92" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=93533b41-4759-422c-bfc1-fd4ca69567f1" ] } ], "mendeley" : { "formattedCitation" : "[3], [18]", "plainTextFormattedCitation" : "[3], [18]", "previouslyFormattedCitation" : "[3], [18]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[3], [18]. The fiber diameter was 125 m and 800 m of fiber was collected. The fiber was coated with a conventional UV-curable acrylate coating (Desolite 3471-3-14, DSM Desotech). As the fiber is drawn, silica from the cladding dissolves into the molten core due to thermally activated mass transport, yielding a graded-index core whose composition contains the aforementioned SiO2 along with the original precursor SrF2-Al2O3 mixture. Hence, this fiber is said to be a SrF2-derived aluminosilicate oxyfluoride fiber; designated SrAlSi-F hereafter. For completeness and for the benefit of the reader, data from a SrO-derived aluminosilicate (i.e., SrAlSi) analog, previously fabricated and reported in ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Cavillon", "given" : "Maxime", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "Joshua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "Courtney J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ryan", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tuggle", "given" : "Matthew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Maxwell", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "Thomas Wade", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "6", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "1435-1441", "title" : "Brillouin Properties of a Novel Strontium Aluminosilicate Glass Optical Fiber", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=e7b75119-034c-474c-a211-ad3f3383869a" ] } ], "mendeley" : { "formattedCitation" : "[10]", "plainTextFormattedCitation" : "[10]", "previouslyFormattedCitation" : "[10]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[10], is used here for comparison and discussion as to the role of the fluorine.
Fiber characterization
Scanning electron microscopy (SEM) analysis was performed on a representative cross section of the fiber using a Hitachi-6600 SEM, at 25 kV, in order to ensure the absence of phase separation in the core and to determine core and cladding diameters. The cross-sectional composition of the fiber was determined by an energy dispersive x-ray (EDX) probe coupled to the SEM.
The refractive index profile (RIP) was measured transversely at a wavelength of 950 nm through the side of the fiber using a Fourier Transform interferometer ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1109/JLT.2009.2032071", "ISBN" : "9780819479761", "ISSN" : "07338724", "abstract" : "A non-destructive technique to measure an optical fiber's refractive index profile with sub-??m spatial resolution over a wavelength range spanning more than one octave (from 480 to 1040 nm) in a single measurement is described. Data showing the variation of refractive index with wavelength for several fiber types is presented.", "author" : [ { "dropping-particle" : "", "family" : "Yablon", "given" : "Andrew D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Lightwave Technology", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2010" ] ] }, "page" : "360-364", "title" : "Multi-wavelength optical fiber refractive index profiling by spatially resolved fourier transform spectroscopy", "type" : "article-journal", "volume" : "28" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=4c7a4c04-2854-4e7d-a1a4-ab37ad069d5f" ] } ], "mendeley" : { "formattedCitation" : "[19]", "plainTextFormattedCitation" : "[19]", "previouslyFormattedCitation" : "[19]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/maste r / c s l - c i t a t i o n . j s o n " } [ 1 9 ] . P r e v i o u s i n v e s t i g a t i o n s h a v e s u g g e s t e d t h a t t h e w a v e l e n g t h d e p e n d e n c e o f t h e c o r e r e f r a c t i v e i n d e x d i f f e r e n c e ( n ) i s p a r t i c u l a r l y s m a l l b e t w e e n 9 5 0 n m a n d 1 5 5 0 n m [ 2 0 ] , t h e r e f o r e i n t r o d u c i n g i n s i g n i f i c a n t e r r o r t o t h e p r e s e n t analysis. Attenuation of the fiber was determined using the cut-back method at a wavelength of 1534 nm.
Raman spectra of the fiber core materials (this reported fiber as well as an analogous fiber from ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Cavillon", "given" : "Maxime", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "Joshua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "Courtney J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ryan", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tuggle", "given" : "Matthew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Maxwell", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "Thomas Wade", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "6", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "1435-1441", "title" : "Brillouin Properties of a Novel Strontium Aluminosilicate Glass Optical Fiber", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=e7b75119-034c-474c-a211-ad3f3383869a" ] } ], "mendeley" : { "formattedCitation" : "[10]", "plainTextFormattedCitation" : "[10]", "previouslyFormattedCitation" : "[10]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[10] that did not possess fluorine) were obtained using a commercial Raman microscope (alpha300, WItech) in a backscattering geometry, utilizing a 532 nm pump source with a focused beam diameter of about 1m and a photon collection time of 120 s per datum. Since gR is determined relative to fused silica (more details provided in Section D), a data point was taken in the cladding of SrAlSi-F fiber, which served a s a r e f e r e n c e v a l u e f o r p u r e f u s e d s i l i c a .
M e t h o d o l o g i e s u s e d t o c h a r a c t e r i z e t h e B r i l l o u i n ( e l a s t i c ) p r o p e r t i e s o f t h e b e r a r e p r o v i d e d i n g r e a t e r d e t a i l e l s e w h e r e A D D I N C S L _ C I T A T I O N { " c i t a t i o n I t e m s " : [ { " i d " : " I T E M - 1 " , " i t e m D a t a " : { " a u t h o r " : [ { "dropping-particle" : "", "family" : "Law", "given" : "Pi-cheng", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Croteau", "given" : "Andr\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optical Materials Express", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "686-699", "title" : "Acoustic coefficients of P2O5-doped silica fiber : the strain-optic and strain-acoustic coefficients", "type" : "article-journal", "volume" : "1" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=146e5742-7b6a-4ba9-b73f-67ecd7614a7c" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1364/OME.1.000686", "ISSN" : "2159-3930", "abstract" : "We present measurements and modeling of the effect of P2O5 doping on the acoustic damping and temperature sensitivity coefficients of silica fibers. In particular, the Brillouin gain spectrum of a highly P-doped fiber is measured and investigated at different temperatures. It is found that the acoustic damping coefficient (proportional to the Brillouin spectral width) of phosphorus pentoxide (1.41 \u00d7 105 m\u22121 for bulk P2O5 at 11 GHz) is similar to, but larger than, that of germanium dioxide. Additionally, the acoustic velocity (and thereby the Stokes\u2019 shift) is found to be much less dependent on temperature in P2O5 ( + 0.12 m/s/\u00b0C) than in SiO2 ( + 0.56 m/s/\u00b0C). Using these coefficients (the thermo-acoustic coefficients), the modeled and unique slopes of the Stokes\u2019-shift-versus-temperature curves for the four observed acoustic modes each lie within 3% of the measured values. Finally, utilizing both the thermo-optic and thermo-acoustic coefficients, a design example is presented where a composition is determined for which the dependence of the Brillouin frequency shift on temperature is minimized. In this example, the calculated temperature sensitivity is less than 5 kHz/\u00b0C over the temperature range \u2212100 \u00b0C < T < 100 \u00b0C for the molar composition 0.54P2O5:0.46SiO2.", "author" : [ { "dropping-particle" : "", "family" : "Law", "given" : "Pi-cheng", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Liu", "given" : "Yuh-shiuan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Croteau", "given" : "Andr\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter D", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Optical Materials Express", "id" : "ITEM-2", "issue" : "4", "issued" : { "date-parts" : [ [ "2011" ] ] }, "page" : "686", "title" : "Acoustic coefficients of P_2O_5-doped silica fiber: acoustic velocity, acoustic attenuation, and thermo-acoustic coefficient", "type" : "article-journal", "volume" : "1" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=c97ffb41-7f02-4b2d-8945-749ea8641057" ] } ], "mendeley" : { "formattedCitation" : "[20], [21]", "plainTextFormattedCitation" : "[20], [21]", "previouslyFormattedCitation" : "[20], [21]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[20], [21]. Briefly, a heterodyne approach i s a p p l i e d t o m e a s u r e t h e B r i l l o u i n G a i n S p e c t r u m ( B G S ) o f t h e b e r . A p r e - a m p l i e d n a r r o w l i n e w i d t h s i g n a l ( <"1 0 0 k H z l i n e w i d t h a t 1 5 3 4 n m ) s e r v e d a s t h e p u m p s o u r c e , w h i l e t h e b a c k - s c a t t e r e d s i g n a l i s c o l l e c t e d t h r o u g h a c i r c u l a t o r a t t h e i n p u t o f t h e f iber under test (FUT). The Rayleigh back-scattered pump and Brillouin signals are mixed on a fast detector and the resultant electrical signal produced is examined utilizing an electrical spectrum analyzer (ESA). The same apparatus was used to measure the temperature and strain dependencies of the Brillouin frequency shift (BFS), by applying either heat (via a thermal bath) or strain (stretching a mechanically well-secured fiber) to the FUT. For both temperature and strain, the dependence of the BFS was found to be linear ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1109/68.34756", "ISBN" : "1041-1135", "ISSN" : "19410174", "abstract" : "Brillouin frequency shift in a single-mode optical fiber has been\\nmeasured as a function of tensile strain. The strain coefficient of\\nnormalized Brillouin frequency shift C≡(dvB/\\ndε)/vB is found to be 4.4 for silica\\nfibers. This result shows the potential of Brillouin spectroscopy to\\nevaluate tensile strain in the fiber with the strain resolution of about\\n2×10-4. The origin of the large strain coefficient is\\ndiscussed", "author" : [ { "dropping-particle" : "", "family" : "Horiguchi", "given" : "Tsuneo", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kurashima", "given" : "Toshio", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tateda", "given" : "Mitsuhiro", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "IEEE Photonics Technology Letters", "id" : "ITEM-1", "issue" : "5", "issued" : { "date-parts" : [ [ "1989" ] ] }, "page" : "107-108", "title" : "Tensile Strain Dependence of Brillouin Frequency Shift in Silica Optical Fibers", "type" : "article-journal", "volume" : "1" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=daa65eca-c4a7-4a57-a3d1-cf885c807e48" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1049/el:19890612", "ISSN" : "00135194", "author" : [ { "dropping-particle" : "", "family" : "Culverhouse", "given" : "D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Farahi", "given" : "F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Pannell", "given" : "C.N.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jackson", "given" : "D.a.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Electronics Letters", "id" : "ITEM-2", "issue" : "14", "issued" : { "date-parts" : [ [ "1989" ] ] }, "page" : "913", "title" : "Potential of stimulated Brillouin scattering as sensing mechanism for distributed temperature sensors", "type" : "article-journal", "volume" : "25" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=f67d7772-0a78-4c90-895b-54620629eb36" ] } ], "mendeley" : { "formattedCitation" : "[22], [23]", "plainTextFormattedCitation" : "[22], [23]", "previouslyFormattedCitation" : "[22], [23]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[22], [23].
In order to estimate gB, the relative Brillouin scattering strength (amplitude of the Brillouin back-scattered s i g n a l ) f r o m a k n o w n l e n g t h o f c o n t r o l b e r ( w h o s e g B i s k n o w n ) i s c o m p a r e d w i t h t h a t f r o m t h e F U T , a l s o o f k n o w n l e n g t h [ 1 0 ] . A P 2 O 5 - d o p e d s i l i c a c o n t r o l b e r w a s u t i l i z e d f o r t h i s m e a s u r e m e n t s i n c e i t i s v e r y w e l l m o d e - m a t c h e d t o t h e f u n d a m e n t a l m o d e o f t h e F U T a n d i t s B G S d o e s n o t o v e r l a p w i t h t h a t o f t h e F U T . T h e m o d e e l d d i a m e t e r s ( M F D s , c a l c u l a t e d f r o m t h e R I P s ) a n d a l l l o s s e s a s s o c i a t e d w i t h t h e m e a s u r e m e n t s w e r e c a r e f u l l y d e t e r m i n e d a s b o t h a r e n e c e s s a r y f o r a n a c c u r a t e e s t i m a t i o n o f g B .
A s i n [ 1 0 ] , a r i n g l a s e r a p p a r a t u s w a s u s e d t o c h a r a c t e r i z e t h e r e f r a c t i v e i n d e x d e p e n d e n c e o n t e m p e r a t u r e a n d l o n g i t u d i n a l s t r a i n ( t h e r m o - o p t i c c o e f c i e n t o r T O C a n d s t r a i n - o p t i c c o e f c i e n t o r S O C , r e s p e c t i v e l y ) . M o r e s p e c i f i c a l l y , t h e r i n g l a s e r w a s c o n s t r u c t e d w ith a segment of FUT forming part of the cavity. Measurements of the change in laser free spectral range (FSR) when the FUT is subjected to either heat or strain allows the determination of the dependence of the fiber (modal) refractive index on these values. For disambiguation, the TOC = dn/dT and the SOC = p12 "( p 1 1 + p 1 2 ) w h e r e p i j a r e t h e P o c k e l s p h o t o e l a s t i c c o e f c i e n t s a n d i s P o i s s o n s r a t i o . M u l t i p l y i n g t h e S O C b y - n 3 / 2 y i e l d s d n / d .
F i n a l l y , t h e n o n l i n e a r r e f r a c t i v e i n d e x , n 2 , w a s e s t i m a t e d v i a a s i m p l e S P M m e a s u r e m e n t . I n t h e s e e x p e r i m e n t s , h i g h p e a k p o w er pulses were propagated through the fiber to experience spectral broadening. The source used for this measurement was a passively mode-locked fiber laser emitting linearly polarized, 750 fs soliton pulses, centered at 1540 nm. The optical pulses were coupled into 4.8 m of SrAlSi-F fiber and the output spectra for different input powers were recorded using an optical spectrum analyzer (OSA). Experimentally, the power coupling efficiency was optimized by checking the output power spectrum and adjusting the input polarization, in the goal to propagate only a single mode through the fiber; the amount of power depleted on the other polarization is considered neglectable. To obtain a value for n2, the measured spectra were compared with numerical modelling using the standard nonlinear Schrdinger equation ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "abstract" : "The field of nonlinear fiber optics has grown substantially since the First Edition of Nonlinear Fiber Optics, published in 1989. Like the First Edition, this Second Edition is a comprehensive, tutorial, and up-to-date account of nonlinear optical phenomena in fiber optics. It synthesizes widely scattered research material and presents it in an accessible manner for students and researchers already engaged in or wishing to enter the field of nonlinear fiber optics. Particular attention is paid to the importance of nonlinear effects in the design of optical fiber communication systems. This is a completely new book containing either new sections or major revisions in every chapter. Major changes in Soliton-based Communication Systems New section on Photonic Switching New section on the Nonlinear Fiber-loop Mirror Section on Second-harmonic Generation will be expanded to include new research material Two new chapters have been added on Fiber Amplifiers and Fiber Lasers, two major research areas which have grown significantly during the last 4-5 years All references have been completely updated", "author" : [ { "dropping-particle" : "", "family" : "Agrawal", "given" : "Govind P", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "edition" : "2nd", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "1995" ] ] }, "number-of-pages" : "592", "publisher" : "Academic Press", "title" : "Nonlinear Fiber Optics", "type" : "book" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=f8b2409b-fa79-4ef6-a46f-1c193750cdba" ] } ], "mendeley" : { "formattedCitation" : "[24]", "plainTextFormattedCitation" : "[24]", "previouslyFormattedCitation" : "[24]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[24], assuming single mode operation.
EXPERIMENTAL RESULTS
Fiber properties
SEM imaging of the fiber cross section was performed and a representative micrograph is provided in Fig. 1. The core and cladding diameters were determined to be 8 m (using RIP, Fig. 3) and 125 m (using SEM imaging, Fig. 1), respectively, and no evidence of phase separation was observed in the core.
Figure 1. Scanning electron microscope (SEM) image of the silica-cladding, strontium aluminosilicate oxyfluoride (SrAlSi-F) core fiber. Note the simple core/cladding geometry in comparison to conventional large mode area (LMA) fibers studied for high energy laser (HEL) applications.
EDX compositional analysis on the same cross-section of fiber showed a graded profile composed of silicon, strontium, aluminum, fluorine and oxygen (Fig. 2). Again, the silicon and some of the oxygen are incorporated into the molten core during the draw due to dissolution/diffusion of silica from the cladding. In addition, the results are presented in atom percent (At. %) since the exact bonding nature of the fluorine is presently unknown (i.e., it has yet to be determined whether the fluorine remains bound to the strontium or preferentially reacts with the aluminum or silicon). In alkaline earth aluminosilicate glasses, studies have shown that fluorine can react and bond to other species in the glass (e.g., Sr or/and Si or/and Al) depending on the glass composition and temperature ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1111/jace.12216", "ISSN" : "00027820", "abstract" : "The model developed by Makishima and Mackenzie (MM) may yield reasonable estimates for the E-modulus of a range of glasses. In the MM model the bonding enthalpy and packing densities present in the compounds that form the glass are taken as input for the calculation. This study shows that a more accurate estimate can be obtained by incorporating in the model structural information from MAS-NMR data. Specifically, we have determined by means of the impulse excitation technique (IET) the E-modulus for ionomer glasses with composition 4.5SiO23Al2O31.5P2O53MO2MF2, where M denotes the alkaline earth metal (M = Mg, Ca, Sr, or Ba). The MAS-NMR structural analysis shows that substitution of calcium by barium or strontium results in a disrupted network, whereas magnesium leads to a more packed network. In this study we will show how a higher coordination state of the aluminum as determined by 27Al MAS-NMR can be taken into account in the model. This leads to rather small corrections of the estimates for these particular glasses. In contrast, the 19F MAS-NMR study shows the presence of AlFM(n) or AlF and SiFM(n) types of environment in the glass network. AlF and SiF bonds are not accounted for in the E-modulus estimate by the MM model. We will show how by incorporating the new bonding of F with Al and Si a significantly improved estimate of the E-modulus is obtained compared with the original model.", "author" : [ { "dropping-particle" : "", "family" : "Swarnakar", "given" : "Akhilesh Kumar", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stamboulis", "given" : "Artemis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Holland", "given" : "Diane", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Biest", "given" : "Omer", "non-dropping-particle" : "Van Der", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of the American Ceramic Society", "id" : "ITEM-1", "issue" : "4", "issued" : { "date-parts" : [ [ "2013" ] ] }, "page" : "1271-1277", "title" : "Improved prediction of young's modulus of fluorine-containing glasses using MAS-NMR structural data", "type" : "article-journal", "volume" : "96" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=3bbca73a-55e0-4249-b470-6c51f403dbdf" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1016/j.jnoncrysol.2003.09.049", "ISBN" : "0022-3093", "ISSN" : "00223093", "abstract" : "Calcium aluminosilicate and calcium fluoro-aluminosilicate glasses have been characterized by 29Si, 27Al and 19F MAS-NMR. The two calcium aluminosilicate glasses examined were based on the composition 2SiO2??Al2O3??2CaO (ART1) and the mineral anorthite 2SiO2??Al2O 3??CaO (ART2). The observed chemical shifts for 29Si and 27Al agreed with previous studies. The fluorine containing glasses were based on 2SiO2??Al2O 3??(2-X)CaO??XCaF2. The 29Si chemical shift moved in a negative direction with increase fluorine content indicating a progressive reduction in the average number of non-bridging oxygens, NBO, attached to a silicon. The 27Al spectra indicated the presence of four coordinate aluminium in the glasses with X = 0.0-0.75, but aluminium was present in Al(IV), Al(V) and Al(VI) coordination states in the highest fluorine content glass with X = 1.0. The 19F spectra indicated the presence of F-Ca(n) in low fluorine content glasses and both F-Ca(n) and Al-F-Ca(n) in high fluorine content glasses. We speculate here that the Al-F-Ca(n) species are oxyfluorides [AlOxFy] n-, where x = 1-6, y = 1-6 and n is the charge on the total complex when aluminium is in Al(IV), Al(V) and Al(VI) coordinate states. The reduction in the average number of NBO per silicon with increasing fluorine content is explained by fluorine converting Ca2+ to F-Ca(n). ?? 2003 Elsevier B.V. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Stamboulis", "given" : "Artemis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hill", "given" : "Robert G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "V.", "family" : "Law", "given" : "Robert", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Non-Crystalline Solids", "id" : "ITEM-2", "issue" : "1", "issued" : { "date-parts" : [ [ "2004" ] ] }, "page" : "101-107", "title" : "Characterization of the structure of calcium alumino-silicate and calcium fluoro-alumino-silicate glasses by magic angle spinning nuclear magnetic resonance (MAS-NMR)", "type" : "article-journal", "volume" : "333" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=2277a8f9-1ddd-4769-8321-8430ebbada49" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.1016/j.jdent.2005.08.005", "ISBN" : "0300-5712", "ISSN" : "03005712", "PMID" : "16522349", "abstract" : "Objective: The aim of this study is to characterise a range of model and commercially available glasses used to form glass (ionomer) polyalkenoate cements. Methods: A range of model fluoro-alumino-silicate glasses that form the basis of glass (ionomer) polyalkenoate cements and five commercial glasses have been characterised by 29Si, 27Al, 31P and 19F Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). Results: The 29Si spectra indicate a predominantly Q33Al and Q44Al structure where the Q33Al species represents a silicon with one non-bridging oxygen and three Si{single bond}O{single bond}Al linkages and the Q44Al species a silicon with four Si{single bond}O{single bond}Al bonds. Aluminium was found in predominantly four coordinate sites, but glasses with high fluorine contents showed an increasing proportion of five and six coordinate aluminium. In phosphate containing glasses the phosphorus was present as Al{single bond}O{single bond}PO3\n2- type species indicating local charge compensation of Al3+ and P5+ in the glass structure. 19F MAS-NMR indicated the presence of F{single bond}Ca(n), Al{single bond}F{single bond}Ca(n), F{single bond}Sr(n), Al{single bond}F{single bond}Sr(n) and Al{single bond}F{single bond}Na(n) species where F{single bond}M(n) indicates a fluorine surrounded by n next nearest neighbour cations and Al{single bond}F{single bond}M(n) represents a fluorine bonded to aluminium with the metal, M in close proximity charge balancing the tetrahedral AlO3F species. The proportion of Al{single bond}F{single bond}M(n) species increased with increasing fluorine content of the glass and lower non-bridging oxygen contents. There was no evidence of Si{single bond}F bonds in any of the glasses. Conclusions: The local structure of the phosphate containing glasses with regard to fluorine, calcium, strontium and phosphate is similar to that of fluorapatite the mineral phase of tooth. This may explain the ease with which these glasses crystallize to fluorapatites and the recently observed mineralization of glass polyalkenoate cements found in vivo. ?? 2006.", "author" : [ { "dropping-particle" : "", "family" : "Hill", "given" : "R. G.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stamboulis", "given" : "A.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "V.", "family" : "Law", "given" : "R.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Dentistry", "id" : "ITEM-3", "issue" : "8", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "525-532", "title" : "Characterisation of fluorine containing glasses by 19F, 27Al, 29Si and 31P MAS-NMR spectroscopy", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=5ee7057b-b9d6-4550-9239-bef5abced80b" ] }, { "id" : "ITEM-4", "itemData" : { "DOI" : "10.1016/S0022-3093(02)01157-2", "ISBN" : "0022-3093", "ISSN" : "00223093", "abstract" : "As part of an ongoing effort to apply Fluorine-19 NMR to understanding the effects of fluoride on the structures and properties of silicate glasses and melts, the local environment of fluorine in several fluorosilicate and fluoroaluminate crystals was explored using 19F MAS NMR. Upon combining this work with recent data, we found the chemical shift generally increases with the radius of the adjoining cation. Also, we found that, in F-La(n) and F-Ca(n) sites, increasing the coordination of the fluorine atom lowers the frequency of the chemical shift. In fluoroaluminates, however, increasing coordination increases the chemical shift. Using this compilation of crystalline data, we analyzed 19F NMR spectra for several silicate and aluminosilicate glasses. The major feature in the Ba silicate glass was a broad peak assigned to F-Ba(n), and a low intensity shoulder was attributed to Si-F-Ba(n). It was impossible to assign the main peak in the Ba aluminosilicate glass to a particular structure, but it was clear that there was a negligible amount of F-Ba(n) present. The Ca aluminosilicate glass had F-Ca(n) units suggested by additional intensity in the higher frequency spinning sidebands, implying that Ca2+ is more effective than Ba2+ in competing with Al3+ for fluorine bonds. ?? 2002 Elsevier Science B.V. All rights reserved.", "author" : [ { "dropping-particle" : "", "family" : "Kiczenski", "given" : "T. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stebbins", "given" : "Jonathan F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of Non-Crystalline Solids", "id" : "ITEM-4", "issue" : "2", "issued" : { "date-parts" : [ [ "2002" ] ] }, "page" : "160-168", "title" : "Fluorine sites in calcium and barium oxyfluorides: F-19 NMR on crystalline model compounds and glasses", "type" : "article-journal", "volume" : "306" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=2d3d869d-cd33-4ef7-8b5b-6ea67f4036ed" ] }, { "id" : "ITEM-5", "itemData" : { "DOI" : "10.2138/am-2015-5201", "ISBN" : "0003-004X", "ISSN" : "19453027", "author" : [ { "dropping-particle" : "", "family" : "Dalou", "given" : "Celia", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Losq", "given" : "Charles", "non-dropping-particle" : "Le", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mysen", "given" : "Bjorn O.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Cody", "given" : "George D.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "American Mineralogist", "id" : "ITEM-5", "issue" : "10", "issued" : { "date-parts" : [ [ "2015" ] ] }, "page" : "2272-2283", "title" : "Solubility and solution mechanisms of chlorine and fluorine in aluminosilicate melts at high pressure and high temperature", "type" : "article-journal", "volume" : "100" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=c252ca9d-e716-4649-ba9a-0971c080f537" ] }, { "id" : "ITEM-6", "itemData" : { "DOI" : "10.1111/j.1551-2916.2005.00677.x", "ISBN" : "0002-7820\\r1551-2916", "ISSN" : "00027820", "abstract" : "We have examined temperature-induced changes in the local structure of fluorine in silicate and aluminosilicate glasses through the application of F-19 magic-angle spinning nuclear magnetic resonance to glasses synthesized with a wide range of fictive temperatures. We have observed an increase in Si-F bonding in binary silicates with increasing temperature, as well as a change in the degree of ordering in mixed modifier silicates. We have also observed an increase in F-Al bonding in alumino-silicates, although the degree of this change appears to be composition dependent. These results could help explain the significant changes in properties of melts on the addition of fluorine.", "author" : [ { "dropping-particle" : "", "family" : "Kiczenski", "given" : "T. J.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Stebbins", "given" : "Jonathan F.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Journal of the American Ceramic Society", "id" : "ITEM-6", "issue" : "1", "issued" : { "date-parts" : [ [ "2006" ] ] }, "page" : "57-64", "title" : "The effect of fictive temperature on the structural environment of fluorine in silicate and aluminosilicate glasses", "type" : "article-journal", "volume" : "89" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=45307bae-0bb1-4060-a7d6-32928a0775b1" ] } ], "mendeley" : { "formattedCitation" : "[25]\u2013[30]", "plainTextFormattedCitation" : "[25]\u2013[30]", "previouslyFormattedCitation" : "[25]\u2013[30]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-cit a t i o n . j s o n " } [ 2 5 ] [ 3 0 ] . I n t h e p r e s e n t f i b e r , t h e m e a s u r e d f l u o r i n e c o n t e n t w a s <"2 . 7 2 A t . % ( 2 . 3 6 W t . % ) a t t h e c o r e c e n t e r , w h i c h i s h i g h e r t h a n t h a t t y p i c a l l y f o u n d i n C V D - d e r i v e d s i l i c a f i b e r s . F r o m t h e E D X d a t a , t h e a t o m i c r a t i o o f [ F ] / [ S r ] w a s d e t e r m i n e d t o b e a b o u t <"0 . 9 1 a t t h e c e n t e r o f t h e c o r e , a r e d u c t i o n b y a b o u t h a l f f r o m t h e i n i t i a l s t o i c h i o m e t r i c v a l u e o f 2 i n t h e S r F 2 p r e c u r s o r . T h i s r e d u c t i o n i s b e l i e v e d t o b e d u e m a i n l y t o t h e f o r m a t i o n o f v o l a t i l e S i F 4 w h e n S r F 2 i s i n c o n t a c t w i t h S i O 2 i n the core melt, similar to CaF2-containing silicate slags ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.2355/isijinternational.47.1711", "ISSN" : "0915-1559", "PMID" : "19530", "abstract" : "In view of the environmental problems assocd. with the evapn. of fluoride from slags and fluxes, a systematic study of the fluoride emission from slags at temps., relevant to steelmaking and casting, has been initiated in the present work. The loss of fluoride from slag melts was monitored by Thermogravimetric Anal. (TGA). The present paper reports the fluoride evapn. in the three binary systems Al2O3-SiO2, CaO-SiO2 and MgO-SiO2 with addns. of CaF2 (ca. 3.5, 5 and 9 wt%). The thermogravimetric expts. were carried out in argon atm. in the isothermal mode in the temp. range 1 673-1 873 K. The gas flow was kept above the starvation rate in order to avoid the gas phase mass transfer step. From the results, the Arrhenius activation energies for the evapn. reaction were evaluated. The activation energies were found to be dependent on temp. and slag chem. for the various slags studied. In binary systems, the activation energy for fluoride evapn. was found to depend on the square of the activity of SiO2 in the slag melt. This correlation obtained in the case of the binary systems could be validated in the case of the results obtained for the ternary system Al2O3-CaO-SiO2 with 5 and 10 wt% of CaF2. The present results are considered to be useful in estg. the fluoride emissions from industrial slags and mold fluxes. [on SciFinder (R)]", "author" : [ { "dropping-particle" : "", "family" : "Persson", "given" : "Mikael", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Seetharaman", "given" : "Sridhar", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Seetharaman", "given" : "Seshadri", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "ISIJ International", "id" : "ITEM-1", "issue" : "12", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "1711-1717", "title" : "Kinetic Studies of Fluoride Evaporation from Slags", "type" : "article-journal", "volume" : "47" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=3c7968f3-e647-44e1-8e2a-f0cefbb16535" ] }, { "id" : "ITEM-2", "itemData" : { "DOI" : "10.1179/030192399677068", "ISSN" : "03019233", "PMID" : "15406", "abstract" : "In the present work, the viscosities of some CaO-CaF2-SiO2 slags were measured using the rotating cylinder method. The effects of various volatile fluorine compds. on the change in slag compn. are discussed on the basis of thermodn. calcns. The kinetic factors concerning the escape of the volatile fluorides under the exptl. conditions were also examd. It was found that the formation of gaseous species SiF4 was the main source for compositional changes during the viscosity measurements. In the case of CaO-CaF2-SiO2 slags, the formation of SiF4 would be somewhat limited owing to the existence of CaO. The compn. change during the measurements was only about \u00b1 1 wt-% for all components in most cases. Viscosity measurements are reported for slags, based on the post-measurement compns. It was found that the addn. of CaF2 causes a significant decrease in viscosity.", "author" : [ { "dropping-particle" : "", "family" : "Shahbazian", "given" : "F", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sichen", "given" : "Du", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Mills", "given" : "K.C.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Seetharaman", "given" : "S.", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Ironmaking & Steelmaking", "id" : "ITEM-2", "issue" : "3", "issued" : { "date-parts" : [ [ "1999" ] ] }, "page" : "193-199", "title" : "Experimental studies of viscosities of some CaO\u2013CaF2\u2013SiO2 slags", "type" : "article-journal", "volume" : "26" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=6865ec59-c393-4ec8-ab14-dbe88274a405" ] }, { "id" : "ITEM-3", "itemData" : { "DOI" : "10.2355/isijinternational.48.739", "ISBN" : "0915-1559", "ISSN" : "0915-1559", "abstract" : "The present paper investigates how the XAl 2 O 3/XSiO 2 ratio in mold slag compositions in a range between 0.06 and 2.14 influences the viscosity of the melt. The objective was to study the variation in viscosity of mould slags if they get enriched in Al 2 O 3 as a result of ...", "author" : [ { "dropping-particle" : "", "family" : "Zhang", "given" : "Zuotai", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Wen", "given" : "Guanghua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tang", "given" : "Ping", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Sridhar", "given" : "Seetharaman", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "ISIJ International", "id" : "ITEM-3", "issue" : "6", "issued" : { "date-parts" : [ [ "2008" ] ] }, "page" : "739-746", "title" : "The Influence of Al2O3/SiO2 Ratio on the Viscosity of Mold Fluxes", "type" : "article-journal", "volume" : "48" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=19df7604-8f3f-40e2-ada5-ba59d30ec23a" ] } ], "mendeley" : { "formattedCitation" : "[31]\u2013[33]", "plainTextFormattedCitation" : "[31]\u2013[33]", "previouslyFormattedCitation" : "[31]\u2013[33]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[31][33].
EMBED Origin50.Graph
Figure 2. Compositional profile across the SrAlSi-F fiber core. Not shown for reasons of clarity is the oxygen concentration, %O. However, %O (At.%) = 100 [%F + %Sr + %Al + %Si].
The measured refractive index profile (RIP) across the fiber core is shown in Fig. 3, relative to the pure silica cladding. Also plotted for comparison is the RIP from the non-fluorine containing SrAlSi fiber of Ref. ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Cavillon", "given" : "Maxime", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "Joshua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "Courtney J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ryan", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tuggle", "given" : "Matthew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Maxwell", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "Thomas Wade", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "6", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "1435-1441", "title" : "Brillouin Properties of a Novel Strontium Aluminosilicate Glass Optical Fiber", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=e7b75119-034c-474c-a211-ad3f3383869a" ] } ], "mendeley" : { "formattedCitation" : "[10]", "plainTextFormattedCitation" : "[10]", "previouslyFormattedCitation" : " [ 1 0 ] " } , " p r o p e r t i e s " : { " n o t e I n d e x " : 0 } , " s c h e m a " : " h t t p s : / / g i t h u b . c o m / c i t a t i o n - s t y l e - l a n g u a g e / s c h e m a / r a w / m a s t e r / c s l - c i t a t i o n . j s o n " } [ 1 0 ] . T h e S r A l S i - F f i b e r e x h i b i t s a n t h a t w a s a b o u t 2 t i m e s l o w e r t h a n t h e S r A l S i f i b e r a t t h e c o r e c e n t e r d u e to a lower doping concentration (i.e., higher silica content) and, additionally, to the presence of the fluorine. Using the well-known expression for the dimensionless V number and assuming that the index is uniform across the 8 m core (as a limiting approximation), the SrAlSi-F fiber exhibits a V number value of <"5 . 2 9 , w h e r e a s t h i s v a l u e i s <"1 0 . 1 2 f o r t h e S r A l S i f i b e r o f [ 1 0 ] . T h e o r i g i n o f t h i s l o w e r V n u m b e r f o r S r A l S i - F f i b e r i s p r i n c i p a l l y a r i s e s f r o m i t s r e d u c e d n , c o m b i n e d w i t h i t s s m a l l c o r e s i z e .
E M B E D O r i g i n 5 0 . G r a p h F i g u r e 3 . M e a s u r e d r e f r a c t i v e i n dex profile (RIP), relative to fused silica (cladding) for the SrAlSi-F fiber (this work) and a SrAlSi fiber (ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "author" : [ { "dropping-particle" : "", "family" : "Cavillon", "given" : "Maxime", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Furtick", "given" : "Joshua", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kucera", "given" : "Courtney J", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ryan", "given" : "Colin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Tuggle", "given" : "Matthew", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jones", "given" : "Maxwell", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Hawkins", "given" : "Thomas Wade", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dragic", "given" : "Peter", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ballato", "given" : "John", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "id" : "ITEM-1", "issue" : "6", "issued" : { "date-parts" : [ [ "2016" ] ] }, "page" : "1435-1441", "title" : "Brillouin Properties of a Novel Strontium Aluminosilicate Glass Optical Fiber", "type" : "article-journal", "volume" : "34" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=e7b75119-034c-474c-a211-ad3f3383869a" ] } ], "mendeley" : { "formattedCitation" : "[10]", "plainTextFormattedCitation" : "[10]", "previouslyFormattedCitation" : "[10]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[10]).
The beneficial effect of fluorine in reducing n in these oxyfluoride glass systems is discussed in section C, and can be employed as an efficient route to fabricate few-mode (such as are typically found in high power fiber laser applications), and ultimately, single mode fibers. As is known, the introduction of Al and Sr oxides to the silica core matrix increases n, and thus the waveguide numerical aperture (NA), compromising single mode operation. There are a number of approaches possible to reduce the number of modes in the fiber. For example, a pedestal design can be implemented ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1117/12.699075", "author" : [ { "dropping-particle" : "", "family" : "Laperle", "given" : "Pierre", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Par\u00e9", "given" : "Claude", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Zheng", "given" : "Huimin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Croteau", "given" : "Andr\u00e9", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "Proceedings of SPIE", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2007" ] ] }, "page" : "1-11", "title" : "Yb-Doped LMA Triple-Clad Fiber for Power Amplifiers", "type" : "article-journal", "volume" : "6453" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=daa42b12-7efa-4c22-aa66-22a411b889a2" ] } ], "mendeley" : { "formattedCitation" : "[34]", "plainTextFormattedCitation" : "[34]", "previouslyFormattedCitation" : "[34]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[34], with the addition of an index-raising inner cladding layer glass to reduce the NA of a central core. If the use of silica cladding offer great advantages, other cladding glass systems can be use in order to reduce fiber NA ADDIN CSL_CITATION { "citationItems" : [ { "id" : "ITEM-1", "itemData" : { "DOI" : "10.1111/ijag.12006", "author" : [ { "dropping-particle" : "", "family" : "Litzkendorf", "given" : "Doris", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Grimm", "given" : "Stephan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schuster", "given" : "Kay", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kobelke", "given" : "Jens", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Schwuchow", "given" : "Anka", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Ludwig", "given" : "Anne", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Kirchhof", "given" : "Johannes", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Leich", "given" : "Martin", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Jetschke", "given" : "Sylvia", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Dellith", "given" : "Jan", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Auguste", "given" : "Jean-louis", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" }, { "dropping-particle" : "", "family" : "Humbert", "given" : "Georges", "non-dropping-particle" : "", "parse-names" : false, "suffix" : "" } ], "container-title" : "International Journal of Applied Glass Science", "id" : "ITEM-1", "issued" : { "date-parts" : [ [ "2012" ] ] }, "page" : "321-331", "title" : "Study of Lanthanum Aluminum Silicate Glasses for Passive and Active Optical Fibers", "type" : "article-journal", "volume" : "331" }, "uris" : [ "http://www.mendeley.com/documents/?uuid=20eb5bf9-e43c-454c-a089-915eb71dcefc" ] } ], "mendeley" : { "formattedCitation" : "[35]", "plainTextFormattedCitation" : "[35]", "previouslyFormattedCitation" : "[35]" }, "properties" : { "noteIndex" : 0 }, "schema" : "https://github.com/citation-style-language/schema/raw/master/csl-citation.json" }[35]. While simpler core-clad step index fiber designs are preferred from a fabrication standpoint, the proposed materials are still amenable to more complicated LMA fibers. In other words, these intrinsically low nonlinearity materials are also compatible with microstructured fiber designs and so a tandem approach of materials, coupled with design could significantly increase optical nonlinearity thresholds.
TABLE I
FIBER PROPERTIES OF SrAlSi-F AND SrAlSi FIBERS
ValueSrAlSi-FSrAlSi****Core diameter (m)810.5Cladding diameter (m)125127 n ( 1 0 - 3 ) * 3 5 . 6 4 0 . 0 0 5 7 4 . 8 V n u m b e r * * 5 . 2 9 1 0 . 1 2 M o d e I n d e x , n m ( 1 5 3 4 n m ; r o o m t e m p . a n d z e r o s t r a i n ) * * * 1 . 4 6 7 3 0 . 0 0 7 1 . 5 1 0 9 M o d e E f f e c t i v e A r e a ( 1 0 - 1 2 m 2 ) * * * 1 8 . 6 2 0 . 0 4 6 . 1 0 A t t e n u a t i o n C o e f f i c i e n t ( d B / m ) a t 1 5 3 4 n m 0 . 6 5 0 . 0 2 2 . 6 8 * V a l u e a t t h e c o r e c e n t e r .
* * C a l c u l a t e d u s i n g 5I = ( 2 5a / 5) " ( 5[5P5\5_5R 2 " 5[5P5Y5N5Q2 ) 1 / 2 , w h e r e a i s t h e c o r e r a d i u s . T h i s a s s u m p t i o n h o l d s f o r a s t e p i n d e x f i b e r , a n d t h e s e n u m b e r s a r e o n l y u s e d a s i n d i c a t o r s . W h e n V <