High-stability, high-pulse-energy MOPA laser system based on composite Nd:YAG crystal with multiple doping concentrations

In this paper, a high-stability, high-pulse-energy laser at a repetition rate of 2 kHz was presented from an electro-optically Q-switched Nd:YAG master oscillator power amplifier (MOPA) system. A multi-segment composite Nd:YAG crystal was utilized as the gain medium of the electro-optically Q-switched laser, yielding a pulse energy of 8.6 mJ and a pulse width of 7.8 ns at 2 kHz. By using two laser diode (LD) end-pumped Nd:YAG amplifiers, the single pulse energy was amplified to 28.6 mJ, corresponding to a peak power of 3.7 MW. By frequency doubling with a LiB₃O₅ (LBO), 13.2 mJ and 6.4 ns laser pulses were achieved at 532 nm. With the temperature varying from −40℃ to 55℃, the coefficient of variation (CV) of the pulse energy was 2.6%. Besides, the laser system also presented high stability under the typical vibration condition of the airborne platform. This MOPA laser system is a promising laser source for airborne remote sensing.