High Energy Narrow Pulse Width Electro-Optical Q-switched Nd: YVO4 Oscillator Without Output Coupler

In this paper, we demonstrate a kHz high energy narrow pulse width electro-optical Q-switched Nd:YVO4 oscillator without output coupler, the resonator is composed of residual reflection from the pump surface and a total reflection mirror. By using a pulsed fiber coupled LD pump source, the thermal effects of Nd:YVO4 can be effectively alleviated. One end facet of the Nd:YVO4 crystal was cut at the Brewster angle to replace the polarizer, thereby reducing the length of the resonator. At a repetition rate of 2 kHz, the laser output achieved the highest average power of 1.49W with an optical-to-optical conversion efficiency of 17.8% and a maximum single pulse energy of 0.745mJ. Additionally, a good beam quality with M-x(2)=1.20 and M-y(2)=1.24 was obtained. The research results presented in this paper greatly enhance the practical applicability of the laser without output coupler, which can be utilized as an oscillating stage in the MOPA (master oscillator power amplifier) configuration.