Single-longitudinal-mode operation of a 1 Watt combined actively and passively Q-switched Cr,Nd:YAG laser

We present a combined actively and passively Q-switched single-frequency laser that uses a codoped Cr4+,Nd3+:YAG crystal and an acousto-optic Q switch. At a maximum of 8.6 W absorbed pump power of fiber-coupled laser-diode arrays, the laser produces pulses of 1036 mW average power with a pulse duration of 8.31 ns at a repetition rate of 7.10 kHz. The output is a stable single longitudinal mode with a linewidth of 530 MHz and an interpulse timing jitter of 0.40 micros. We compare the laser with and without the Cr4+ as well as with and without an active Q switch.