High-repetition-rate 300-ps pulsed ultraviolet source with a passively Q-switched microchip laser and a multipass amplifier

We demonstrate a new kind of picosecond laser source in the UV at a high re petition rate of -45 kHz, using only passive, compact, and simple elements. This system is based on a microchip laser and a very efficient multipass a mplifier, both pumped with recently developed high-brightness laser diodes. The system has been optimized to deliver, at a high repetition rate, subna nosecond pulses at the wavelength 355 nm with an energy per pulse of close to 1 mu J (38-mW average power). 300-ps UV laser source at this high repeti tion rate. This source is to our knowledge the first totally passive (C) 19 99 Optical Society of America.