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Amplification of a radially polarized beam in a thermally-guiding fiber-rod amplifier

Amplification of a radially polarized beam in a thermally-guiding fiber-rod amplifier
Amplification of a radially polarized beam in a thermally-guiding fiber-rod amplifier
Laser and optical amplifier geometries may be split into categories such as rod and fiber. Rod gain media are susceptible to thermal effects at high power, whereas fiber suffer from detrimental non-linear effects due to their long length and small mode areas. Here we present an application of a hybrid architecture between the two geometries – the Thermally-Guiding Fiber-Rod (TGFR). The TGFR inherits the large mode area of the rod amplifier, the high surface area of a fiber, and exploits thermal lensing to guide modes.

We present a successful demonstration of amplification of a radially polarized mode using the TGFR. A 1030 nm continuous-wave radially polarized seed source of high purity and beam quality (M2=1.9±0.1) was constructed using thermal bifocussing in a Yb:YAG crystal to provide mode selection. This seed source was carefully focussed into the 300 µm core of a 10 cm long sample of commercially available triple-clad Yb-doped silica fiber in order to satisfy the thermal guidance condition and avoid waveguiding due to the refractive index step. The TGFR was pumped using a high power 915 nm diode laser.

The radially polarized mode was preserved through transmission of the TGFR. The output beam polarization was maintained at 99.1% purity while the M2 factor was measured to be 2.1±0.1. The maximum output power was 12.6 W of radially polarized light, corresponding to a gain of 7.0 dB limited by available pump power. This promising geometry the potential for further power scaling of radially-polarized beams for application in laser processing.
Fiber lasers and amplifiers, cylindrical vector, radially polarized, Yb-doped fiber amplifiers
SPIE
Jefferson-Brain, Thomas, Lewis
8bce2a02-37a4-4277-a8cb-0c40bde57837
Smith, Callum R
00a3e4af-743b-4c7f-b1df-bb142e176d63
Burns, Mark
7f7ca346-f31a-46cf-a848-acb4bcae18b9
Shardlow, Peter
9ca17301-8ae7-4307-8bb9-371df461520c
Clarkson, W.A.
3b060f63-a303-4fa5-ad50-95f166df1ba2
Jefferson-Brain, Thomas, Lewis
8bce2a02-37a4-4277-a8cb-0c40bde57837
Smith, Callum R
00a3e4af-743b-4c7f-b1df-bb142e176d63
Burns, Mark
7f7ca346-f31a-46cf-a848-acb4bcae18b9
Shardlow, Peter
9ca17301-8ae7-4307-8bb9-371df461520c
Clarkson, W.A.
3b060f63-a303-4fa5-ad50-95f166df1ba2

Jefferson-Brain, Thomas, Lewis, Smith, Callum R, Burns, Mark, Shardlow, Peter and Clarkson, W.A. (2019) Amplification of a radially polarized beam in a thermally-guiding fiber-rod amplifier. In Solid State Lasers XXVIII: Technology and Devices. SPIE. 1 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

Laser and optical amplifier geometries may be split into categories such as rod and fiber. Rod gain media are susceptible to thermal effects at high power, whereas fiber suffer from detrimental non-linear effects due to their long length and small mode areas. Here we present an application of a hybrid architecture between the two geometries – the Thermally-Guiding Fiber-Rod (TGFR). The TGFR inherits the large mode area of the rod amplifier, the high surface area of a fiber, and exploits thermal lensing to guide modes.

We present a successful demonstration of amplification of a radially polarized mode using the TGFR. A 1030 nm continuous-wave radially polarized seed source of high purity and beam quality (M2=1.9±0.1) was constructed using thermal bifocussing in a Yb:YAG crystal to provide mode selection. This seed source was carefully focussed into the 300 µm core of a 10 cm long sample of commercially available triple-clad Yb-doped silica fiber in order to satisfy the thermal guidance condition and avoid waveguiding due to the refractive index step. The TGFR was pumped using a high power 915 nm diode laser.

The radially polarized mode was preserved through transmission of the TGFR. The output beam polarization was maintained at 99.1% purity while the M2 factor was measured to be 2.1±0.1. The maximum output power was 12.6 W of radially polarized light, corresponding to a gain of 7.0 dB limited by available pump power. This promising geometry the potential for further power scaling of radially-polarized beams for application in laser processing.

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Amplification of a radially polarized beam in a thermally-guiding fiber-rod amplifier - Author's Original
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More information

Published date: 6 February 2019
Venue - Dates: SPIE Photonics West LASE 2019, San Francisco, United States, 2019-02-03 - 2019-02-07
Keywords: Fiber lasers and amplifiers, cylindrical vector, radially polarized, Yb-doped fiber amplifiers

Identifiers

Local EPrints ID: 429360
URI: https://eprints.soton.ac.uk/id/eprint/429360
PURE UUID: 35b1b89a-eafa-4cfd-a30d-7e1a227de2a5
ORCID for Thomas, Lewis Jefferson-Brain: ORCID iD orcid.org/0000-0002-8838-5640
ORCID for Mark Burns: ORCID iD orcid.org/0000-0003-2039-6025
ORCID for Peter Shardlow: ORCID iD orcid.org/0000-0003-0459-0581

Catalogue record

Date deposited: 26 Mar 2019 17:30
Last modified: 09 Apr 2019 00:32

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Contributors

Author: Thomas, Lewis Jefferson-Brain ORCID iD
Author: Callum R Smith
Author: Mark Burns ORCID iD
Author: Peter Shardlow ORCID iD
Author: W.A. Clarkson

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