Passively Q-switched single-frequency Nd:YVO 4 ring laser with external feedback

A compact diode-pumped Nd:YVO4 ring laser was developed for generation of relatively long (few tens nanoseconds) single-frequency pulses for high-spectral-resolution LIDAR applications. Exploiting the feedback from an external mirror and Cr:YAG passive Q-switching with pulsed pump, unidirectional single-frequency operation with high quality ∼50-ns, 80-µJ TEM00 pulses was achieved from 100 Hz to 10 kHz. Amplitude, duration and repetition rate stability of the pulses was better than 1%.