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13 March 2019 High energy amplification of ultrafast pulses in a planar waveguide geometry (Conference Presentation)
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We present an energy-scalable ultrafast Yb:YAG MOPA system for material processing applications. The system consists of a dual-side-pumped Yb:YAG planar waveguide (PWG) amplification stage that is seeded by a commercial laser, pre-amplified by a dual-end-pumped Yb:YAG single crystal fibre (SCF). The SCF is pumped by two 80 W fibre-coupled laser diodes and amplified the seed (344 fs pulses, 10 MHz, 140 nJ) to 1.4 µJ in a single-pass configuration. Thermal lensing, astigmatism and depolarisation within the SCF was analysed and compensated for by careful selection of beam-shaping optics. The 12 mm wide by 13 mm long PWG crystal has a 150 µm core of 2 at.% Yb:YAG, bonded top and bottom to sapphire cladding of 1 mm thickness. The core is side-pumped using two 540 W phase-corrected diode stacks such that a uniformly distributed high gain was achieved. The advanced crystal design suppresses intra-crystal parasitic oscillations and the PWG geometry significantly alleviates thermal lensing. The seed is multi-passed through the PWG crystal and the mirror parameters were carefully chosen to optimise gain extraction. The seed path is scalable up to 7 passes through the crystal for which 8.7 µJ per pulse was achieved at a pump power of 860 W for sub-ps pulses at 10 MHz. Current investigations include suppression of unwanted parasitic oscillations between the multi-pass mirrors to improve the output beam quality. Future work is aimed at the inclusion of kHz burst modes of sub-ps pulses at 1MHz repetition frequency.
Conference Presentation
© (2019) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kimberly E. Tkalcec, Rolf B. Birch, Howard J. Baker, and M. J. Daniel Esser "High energy amplification of ultrafast pulses in a planar waveguide geometry (Conference Presentation)", Proc. SPIE 10896, Solid State Lasers XXVIII: Technology and Devices, 108960S (13 March 2019);


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