60W Ho:YLF oscillator-amplifier system

Wayne Koen; Cobus Jacobs; Lorinda Wu; Hencharl J. Strauss

doi:10.1117/12.2078786

20 February 2015 60W Ho:YLF oscillator-amplifier system

Wayne Koen, Cobus Jacobs, Lorinda Wu, Hencharl J. Strauss

Proceedings Volume 9342, Solid State Lasers XXIV: Technology and Devices; 93421Y (2015) https://doi.org/10.1117/12.2078786
Event: SPIE LASE, 2015, San Francisco, California, United States

Abstract

We developed a compact Ho:YLF oscillator–amplifier system end-pumped by two 54 W unpolarised Tm:fibre lasers, and produced 60.2 W of output power at 2064 nm. The oscillator consisted of a flat input coupler mirror, a 50 mm long 0.5 % doped Ho:YLF crystal rod, a 45 degree folding mirror, an AOM, and a concave output coupler mirror. The oscillator operated vertically polarised on the holmium crystal’s σ–polarisation, ensuring good beam quality from the weak thermal lens. The concave output coupler had a radius of 300 mm and a reflectivity of 82 % at 2064 nm. The oscillator gave a maximum output of 24 W with an M²of 1.06. The single-pass amplifier consisted of two 40 mm long, 0.5 % doped, Ho:YLF crystal rods and four folding mirrors. While the seed laser was pumped by a single fibre laser, the amplifier utilized the transmitted pump light from the seed laser in addition to the second fibre laser. With the first crystal amplifying on the σ–polarisation and the second crystal on the π-polarisation, the amplifier delivered 60.2 W with an M² of 1.09, representing a gain of 2.5 while achieving an optical-to-optical efficiency of 55.5 %. When Q-switched with the AOM, the system delivered pulse lengths of between 43 and 113 ns at repetition rates from 15 to 40 kHz.

Citation Download Citation

Wayne Koen, Cobus Jacobs, Lorinda Wu, and Hencharl J. Strauss "60W Ho:YLF oscillator-amplifier system", Proc. SPIE 9342, Solid State Lasers XXIV: Technology and Devices, 93421Y (20 February 2015); https://doi.org/10.1117/12.2078786

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