Multi-longitudinal-mode oscillation of self-Q-switched Cr,Yb:YAG laser with a plano-concave resonator

Stable longitudinal multi-mode chromium and ytterbium co-doped Cr,Yb:YAG self-Q-switched laser formed by a plano-concave resonator has been demonstrated at room temperature without cooling system. An average output power of as much as 70 mW at 1.03 μm with a pulse width (FWHM) as short as 12.3 ns was obtained with 5% transmission output coupler. High beam quality (M2 < 2.4) output with transverse gaussian profile was obtained. The non-linear mode coupling effects of this longitudinal multi-mode laser was investigated and stable pulse sequence was attributed to the non-linear mode coupling effects between main mode oscillation and the side-mode oscillation.