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A novel fiber design for efficient Nd-doped fibre lasers in the 1-5W power range

A novel fiber design for efficient Nd-doped fibre lasers in the 1-5W power range
A novel fiber design for efficient Nd-doped fibre lasers in the 1-5W power range
For many applications in telecommunication, sensing and spectroscopy reliable all-solid state laser light sources are desirable. The great variety on ionic species of the lanthanides with which the host material of fiber lasers may be doped enables to cover the spectral range between 0.9 and 3µm. Besides tunability a high output power is often desirable calling for an adaption of the fiber design on the beam parameter product of high power diode laser arrays used as pump sources. The recently developed double clad fibers [1] fulfil these demands. The extraction efficiency of this fibers is very high (>90%) but the absorption of the pump light is considerably low due to the unavoidable appearance of gallery modes. Decentred cores. periodical bending or mode scrambling [2] can improve this efficiency up to about 70%. In order to increase the output power and the absorption of the pump light we have chosen another fiber design which minimises the problems encountered with the gallery modes. The fiber consist of an undoped core of large diameter and a doped glass cladding surrounded by a coating. The refractive indices obey the relation nclad > ncore >> ncoat. The refractive index/doping profile recommends to the designation M-profile fiber (MPF). Its d 1a. Fig. 1b shows by a ray optics picture the pump- and laser light propagation. Moreover, it is shown that MPFs may be evanescently coupled because laser light guiding occurs near the surface of the structure through which the output power can be scaled up to even higher values. The optimum lengths for a double clad fiber and a MPF behave as 20: 1. The pump power remaining in a 100 cm long MPF doped with 5000 ppm Nd2O3 is less than 5%. Output powers in excess of 1W with a slope efficiency of about 27% have been achieved, cf Fig. 2.
We report on first experiments generating uniphase radiation from a stable (azimuthally) multimode beam and on the radiation properties of an evanescently coupled array of MPFs.
397
IEEE
Glas, P.
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Naumann, M.
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Schirrmacher, A.
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Dong, L.
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Caplen, J.
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Glas, P.
1e09074b-ffe8-4394-81e6-34eedd23a753
Naumann, M.
d7e2adb6-5435-4fad-850c-ace9e5ba90a8
Schirrmacher, A.
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Dong, L.
4a30a247-d676-42ef-aaf4-061579d6d64e
Caplen, J.
c79f7963-556a-4fb2-a1c5-c138d35b0b9a

Glas, P., Naumann, M., Schirrmacher, A., Dong, L. and Caplen, J. (1996) A novel fiber design for efficient Nd-doped fibre lasers in the 1-5W power range. In Proceedings of Conference on Lasers and Electro Optics (CLEO 96). IEEE. p. 397 .

Record type: Conference or Workshop Item (Paper)

Abstract

For many applications in telecommunication, sensing and spectroscopy reliable all-solid state laser light sources are desirable. The great variety on ionic species of the lanthanides with which the host material of fiber lasers may be doped enables to cover the spectral range between 0.9 and 3µm. Besides tunability a high output power is often desirable calling for an adaption of the fiber design on the beam parameter product of high power diode laser arrays used as pump sources. The recently developed double clad fibers [1] fulfil these demands. The extraction efficiency of this fibers is very high (>90%) but the absorption of the pump light is considerably low due to the unavoidable appearance of gallery modes. Decentred cores. periodical bending or mode scrambling [2] can improve this efficiency up to about 70%. In order to increase the output power and the absorption of the pump light we have chosen another fiber design which minimises the problems encountered with the gallery modes. The fiber consist of an undoped core of large diameter and a doped glass cladding surrounded by a coating. The refractive indices obey the relation nclad > ncore >> ncoat. The refractive index/doping profile recommends to the designation M-profile fiber (MPF). Its d 1a. Fig. 1b shows by a ray optics picture the pump- and laser light propagation. Moreover, it is shown that MPFs may be evanescently coupled because laser light guiding occurs near the surface of the structure through which the output power can be scaled up to even higher values. The optimum lengths for a double clad fiber and a MPF behave as 20: 1. The pump power remaining in a 100 cm long MPF doped with 5000 ppm Nd2O3 is less than 5%. Output powers in excess of 1W with a slope efficiency of about 27% have been achieved, cf Fig. 2.
We report on first experiments generating uniphase radiation from a stable (azimuthally) multimode beam and on the radiation properties of an evanescently coupled array of MPFs.

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Published date: 1996
Venue - Dates: Conference on Lasers and Electro-Optics (CLEO'96), Anaheim, Anaheim, United States, 1996-06-02 - 1996-06-07

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Local EPrints ID: 76883
URI: http://eprints.soton.ac.uk/id/eprint/76883
PURE UUID: 93fb9190-717a-48d8-b16a-4fd4c423e8ea

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Date deposited: 11 Mar 2010
Last modified: 13 Mar 2024 23:38

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Contributors

Author: P. Glas
Author: M. Naumann
Author: A. Schirrmacher
Author: L. Dong
Author: J. Caplen

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