Nd3+- and Cr3+-Doped Yttrium Aluminum Garnet Ceramic Pulse Laser Using Cr4+-Doped Yttrium Aluminum Garnet Crystal Passive Q-Switch

Abstract

A passively Q-switched Nd3+-and Cr3+-doped yttrium aluminum garnet (YAG) ceramic laser using Cr4+:YAG crystal as a Q-switch element is reported for the first time. Unique temporal waveforms of the output laser pulses were observed. A temporal waveform of a Q-switched laser pulse was compared with one in a free-running pulse. Laser pulses of 130–300 ns duration were generated. A maximum output laser energy of 1.1 J and an average peak power of 0.1 MW were obtained for multiple Q-switched pulses by a single shot, and a maximum output laser energy of 80 mJ was obtained for a single pulse. The evaluated maximum peak power was 0.6 MW as determined from measured pulse energy and duration. The effective saturation fluence and maximum stored energy were lower than those of Nd:YAG. However, a high peak power can be obtained using an output coupler with a low reflectivity owing to the high gain as in the case of Nd:YAG. The threshold of the Nd/Cr:YAG ceramic laser oscillator is reduced to less than 10% of that of a Nd:YAG oscillator. It was determined by calculation that the output laser energy of the Nd/Cr:YAG ceramic laser was close to 4 times that of Nd:YAG.