Abstract:
Background Yb:YAG thin-disk lasers are promising high-power solid-state laser sources because the thin-disk geometry enables efficient heat removal and suppresses thermal lensing. However, the small disk thickness limits single-pass pump absorption, and multi-pass pumping is required. Zero-phonon-line pumping near 969 nm can further reduce the quantum defect and thermal load compared with conventional 940 nm pumping.
Purpose This study aims to develop an all-domestic high-power and high-efficiency Yb:YAG thin-disk laser based on a self-developed disk crystal and a 56-pass pump module, and to experimentally verify its output performance and thermal characteristics under high-power continuous operation.
Methods Firstly, a high-power thin-disk laser system was built using a self-developed 10% doped, 130 μm thick Yb:YAG disk crystal and a self-developed 56-pass pump module. Secondly, the single-pass absorption rates at 940 nm and 969 nm were measured, and the cumulative absorption after 56 passes was estimated. Thirdly, a V-shaped resonator with the same cavity structure, output coupler and cooling conditions was used for both pump wavelengths, and the disk surface temperature, output power and optical-to-optical efficiency were measured.
Results Under the same pump power density, 969 nm pumping showed lower disk temperature and higher optical-to-optical efficiency than 940 nm pumping. At 4.7 kW/cm2, the maximum surface temperature was 72 ℃ for 969 nm pumping and 80 ℃ for 940 nm pumping. With 969 nm pumping, the system achieved 906 W multimode output at 1300 W pump power, with a maximum optical-to-optical efficiency of 69.7%, compared with 62% for 940 nm pumping.
Conclusions The results show that the 56-pass pump module enables nearly saturated pump absorption, and 969 nm zero-phonon-line pumping reduces thermal load and improves efficiency. This work provides an experimental basis for all-domestic Yb:YAG thin-disk laser systems.
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