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Enhanced photorefractivity in germanosilicate fibres: Effects of bleaching with 488nm Light

Enhanced photorefractivity in germanosilicate fibres: Effects of bleaching with 488nm Light
Enhanced photorefractivity in germanosilicate fibres: Effects of bleaching with 488nm Light
Permanent index changes, Delta.n, of the order of 10-4 at 633 nm are induced in germanosilicate optical fibers by exposure to light at 488,266, and 240 nm. This photorefractivity has great potential in the fabrication of efficient grating-based devices for a wide range of WDM and lasing applications. It has been explained in terms of alterations in the UV absorption spectrum yielding (through the Kramers-Kronig relation) almost dispersion-free Delta.n values between 500 nm and 1.5 µm. The predominant cause is the movement of electrons from broken oxygen deficient Ge-Si bonds (associated absorption peak at 240 nm) to Ge(2) traps (when occupied by an electron an absorption peak appears at 213 nm) (see Fig. 1). The Ge-Si bonds can be broken by single-photon absorption of 240-or 266-nm light (permitting gratings of any period to be fabricated by side writing), or (much more slowly) by two-photon absorption (TPA) of 488-nm light. However, an undesirable side effect of 266-nm treatment is that the absorption induced for approximately the same Delta.n value is some two orders of magnitude larger than that obtained with 488-nm light (30 dB/m at 633 nm). This absorption is attributed to the creation of Ge(1) color centers, with a broad absorption peak centered at 281 nm and extending into the visible (Fig. 1). Because the balance between bleaching and trapping at Ge(1)and Ge(2) dopant sites is different for 266-nm light, it seemed possible that the population of Ge(1) centers could be depleted by 488-nm light, perhaps even enhancing the induced Delta.n.
Hand, D.P.
a08ad5b2-7543-4a99-a1d2-e14934ee0faf
Poyntz-Wright, L.J.
1acbc672-a9cb-4183-a841-82c52831bfb3
Russell, P.St.J.
77db5e8d-8223-4806-ae60-a106619a022a
Hand, D.P.
a08ad5b2-7543-4a99-a1d2-e14934ee0faf
Poyntz-Wright, L.J.
1acbc672-a9cb-4183-a841-82c52831bfb3
Russell, P.St.J.
77db5e8d-8223-4806-ae60-a106619a022a

Hand, D.P., Poyntz-Wright, L.J. and Russell, P.St.J. (1990) Enhanced photorefractivity in germanosilicate fibres: Effects of bleaching with 488nm Light. Integrated Photonics Research. 26 - 28 Mar 1990.

Record type: Conference or Workshop Item (Other)

Abstract

Permanent index changes, Delta.n, of the order of 10-4 at 633 nm are induced in germanosilicate optical fibers by exposure to light at 488,266, and 240 nm. This photorefractivity has great potential in the fabrication of efficient grating-based devices for a wide range of WDM and lasing applications. It has been explained in terms of alterations in the UV absorption spectrum yielding (through the Kramers-Kronig relation) almost dispersion-free Delta.n values between 500 nm and 1.5 µm. The predominant cause is the movement of electrons from broken oxygen deficient Ge-Si bonds (associated absorption peak at 240 nm) to Ge(2) traps (when occupied by an electron an absorption peak appears at 213 nm) (see Fig. 1). The Ge-Si bonds can be broken by single-photon absorption of 240-or 266-nm light (permitting gratings of any period to be fabricated by side writing), or (much more slowly) by two-photon absorption (TPA) of 488-nm light. However, an undesirable side effect of 266-nm treatment is that the absorption induced for approximately the same Delta.n value is some two orders of magnitude larger than that obtained with 488-nm light (30 dB/m at 633 nm). This absorption is attributed to the creation of Ge(1) color centers, with a broad absorption peak centered at 281 nm and extending into the visible (Fig. 1). Because the balance between bleaching and trapping at Ge(1)and Ge(2) dopant sites is different for 266-nm light, it seemed possible that the population of Ge(1) centers could be depleted by 488-nm light, perhaps even enhancing the induced Delta.n.

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Published date: 1990
Venue - Dates: Integrated Photonics Research, 1990-03-26 - 1990-03-28
Organisations: Optoelectronics Research Centre

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Local EPrints ID: 77486
URI: https://eprints.soton.ac.uk/id/eprint/77486
PURE UUID: dd9b4105-5f42-4b24-bca6-bd6f21ce1594

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Date deposited: 11 Mar 2010
Last modified: 18 Jul 2017 23:32

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Contributors

Author: D.P. Hand
Author: L.J. Poyntz-Wright
Author: P.St.J. Russell

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