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Generation and amplification of a LG01 laser with a thermally-guiding fiber-rod (Conference Presentation)
Author(s): Thomas L. Jefferson-Brain; Qiyao Liu; Peter C. Shardlow; William A. Clarkson
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Paper Abstract

Laguerre-Gaussian (LG) modes have properties that make them well suited to many applications, particularly laser processing when scaled to high-power. Here we present an approach for generating high-purity LG01 vortex beams in a Nd:YVO4 laser which overcomes the common problems of degenerate handedness and low damage thresholds in previous methods. The obtained modes are scaled in power by application of a novel Thermally-Guiding Fiber-Rod Amplifier (TGFRA). Our approach is based on a novel end-pumping arrangement for efficiently generating the Hermite-Gaussian TEM01 mode in a 1064 nm Nd:YVO4 laser. A fiber-coupled laser diode was spliced to a 50:50 fiber splitter to give two equal outputs. These outputs were bonded to a bulk optic with a small separation for spatially matching the TEM01 mode. An astigmatic mode converter made using two concave mirrors was used to obtain a LG01 mode with controlled handedness. The obtained LG01 mode was propagated through the 300 µm core of a 10 cm long sample of triple-clad Yb-doped silica fiber by utilizing thermal lensing as a waveguiding mechanism. The fiber was pumped using a high-power 915 nm diode laser. This amplifier geometry ensures preservation of the mode while the inheriting good thermal management from a fiber geometry and the large mode area common in rod geometries. The 0.89 W LG01 seed-source was amplified with gain of 2.7 dB. The gain was limited by available pump power and the emission cross-section at 1064 nm. This result provides an avenue to high-power LG01 modes.

Paper Details

Date Published: 13 March 2019
Proc. SPIE 10896, Solid State Lasers XXVIII: Technology and Devices, 108961A (13 March 2019); doi: 10.1117/12.2511648
Show Author Affiliations
Thomas L. Jefferson-Brain, Univ. of Southampton (United Kingdom)
Qiyao Liu, Fudan Univ. (China)
Univ. of Southampton (United Kingdom)
Peter C. Shardlow, Univ. of Southampton (United Kingdom)
William A. Clarkson, Univ. of Southampton (United Kingdom)

Published in SPIE Proceedings Vol. 10896:
Solid State Lasers XXVIII: Technology and Devices
W. Andrew Clarkson; Ramesh K. Shori, Editor(s)

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