Multi-order Stokes output based on intra-cavity KTiOAsO₄ Raman crystal

We report efficient multi-Stokes Raman output of a KTiOAsO4 (KTA) crystal driven by a laser diode end-pumped acousto-optic Q-switched Nd:YAG laser. The Raman outputs of two x-cut KTA crystals, one with a length of 20 mm and the other one of 25-mm, were experimentally compared. Under an incident pump power of 10.9 W, a maximum output power of 1.12 W with a pulse width of 7.6 ns and a pulse repetition frequency of 15 kHz were obtained. The conversion efficiency and slope efficiency with respect to the incident diode pump power were 10.3% and 15.2%, respectively. The laser output contains multiple Raman Stokes lines with different spectral strengths that varied with the pump power.