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Radially-polarised beam amplification in an Yb:YAG thin-slab architecture

Radially-polarised beam amplification in an Yb:YAG thin-slab architecture
Radially-polarised beam amplification in an Yb:YAG thin-slab architecture
Radially-polarised beams are attracting growing interest owing to their unique properties and numerous applications, including materials processing. Power-scaling whilst preserving the polarisation-purity of radially-polarised beams is challenging, with efforts predominantly focused on cylindrically-symmetric systems.

We explore an alternative strategy for power-scaling radially-polarised beams using a thin slab amplifier geometry, which, to the best of our knowledge, has not been previously investigated. We show that very high radial polarisation-purity can be maintained in an architecture that can be operated at high powers.

A radially-polarised seed-source was constructed using an Yb:YAG rod in a plane-parallel configuration, pumped by a capillary delivery-fiber which provided effective overlap with the LG01 mode. By tuning the cavity length and utilising thermally-induced birefringence, a robust multi-Watt LG01 mode was generated with an excellent radial polarisation-purity of 15dB and good beam quality M2=2.2.

The Yb:YAG slab was pumped by a diode-bar producing a highly-elongated inversion region. The seed was amplified in a double-pass configuration, using a cylindrical lens to spatially-match the inversion. The output beam was re-collimated by the cylindrical lens, and compensation for the Gouy phase-shift was made using a half-waveplate.

At 50W of incident pump power we obtained a small-signal gain of 7.5dB and a power-gain of 4.5dB for 1.45W seed power. At maximum pump power the radial polarisation-purity was maintained at 15dB, whilst the beam quality was degraded slightly to M2=2.3. Further optimisation of slab design and pump geometry will be discussed in addition to power scaling the system to higher output powers necessary for numerous applications.
Smith, Peter
8979668a-8b7a-4838-9a74-1a7cfc6665f6
Beecher, Stephen J.
b3664adc-d6b5-4a5a-a09a-8e1415c6d3f5
Mackenzie, Jacob
1d82c826-fdbf-425b-ac04-be43ccf12008
Clarkson, W.A.
3b060f63-a303-4fa5-ad50-95f166df1ba2
Smith, Peter
8979668a-8b7a-4838-9a74-1a7cfc6665f6
Beecher, Stephen J.
b3664adc-d6b5-4a5a-a09a-8e1415c6d3f5
Mackenzie, Jacob
1d82c826-fdbf-425b-ac04-be43ccf12008
Clarkson, W.A.
3b060f63-a303-4fa5-ad50-95f166df1ba2

Smith, Peter, Beecher, Stephen J., Mackenzie, Jacob and Clarkson, W.A. (2017) Radially-polarised beam amplification in an Yb:YAG thin-slab architecture. SPIE Photonics West 2017, San Francisco, United States. 27 Jan - 01 Feb 2017. (doi:10.1117/12.2256298).

Record type: Conference or Workshop Item (Paper)

Abstract

Radially-polarised beams are attracting growing interest owing to their unique properties and numerous applications, including materials processing. Power-scaling whilst preserving the polarisation-purity of radially-polarised beams is challenging, with efforts predominantly focused on cylindrically-symmetric systems.

We explore an alternative strategy for power-scaling radially-polarised beams using a thin slab amplifier geometry, which, to the best of our knowledge, has not been previously investigated. We show that very high radial polarisation-purity can be maintained in an architecture that can be operated at high powers.

A radially-polarised seed-source was constructed using an Yb:YAG rod in a plane-parallel configuration, pumped by a capillary delivery-fiber which provided effective overlap with the LG01 mode. By tuning the cavity length and utilising thermally-induced birefringence, a robust multi-Watt LG01 mode was generated with an excellent radial polarisation-purity of 15dB and good beam quality M2=2.2.

The Yb:YAG slab was pumped by a diode-bar producing a highly-elongated inversion region. The seed was amplified in a double-pass configuration, using a cylindrical lens to spatially-match the inversion. The output beam was re-collimated by the cylindrical lens, and compensation for the Gouy phase-shift was made using a half-waveplate.

At 50W of incident pump power we obtained a small-signal gain of 7.5dB and a power-gain of 4.5dB for 1.45W seed power. At maximum pump power the radial polarisation-purity was maintained at 15dB, whilst the beam quality was degraded slightly to M2=2.3. Further optimisation of slab design and pump geometry will be discussed in addition to power scaling the system to higher output powers necessary for numerous applications.

Full text not available from this repository.

More information

Published date: 1 February 2017
Venue - Dates: SPIE Photonics West 2017, San Francisco, United States, 2017-01-27 - 2017-02-01

Identifiers

Local EPrints ID: 413344
URI: https://eprints.soton.ac.uk/id/eprint/413344
PURE UUID: b4157184-caaa-441d-b56e-e555616d29be
ORCID for Jacob Mackenzie: ORCID iD orcid.org/0000-0002-3355-6051

Catalogue record

Date deposited: 22 Aug 2017 16:31
Last modified: 14 Mar 2019 01:47

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