Highly efficient RTP electro-optic Q-switched Nd: YVO₄ laser by end-pumping at 914 nm

An electro-optic (EO) Q-switched Nd:YVO4 laser with high repetition rate, end-pumped by continuous-wave (CW) laser diode (LD) was reported. Using RbTiOPO4 (RTP) single crystal as an EO Q-switch, by matching mode of oscillation light and pump light, 1 064 nm laser output with high efficiency, high repetition and short pulse width was realized. On the one hand, low absorption coefficient of 914 nm wavelength was adopted to pump Nd:YVO4 crystal, so that the heat distribution inside the crystal was uniform, thereby achieving high quantum efficiency while reducing the thermal effect. On the other hand, the pump light spot radius was optimized to match mode of pump light and oscillation light. At the repetition rate of 200 kHz, the maximum average output power of 16 W, full width at half maximum of pulses of 9 ns, single pulse energy of 80 J and beam quality M21.2 are achieved at an absorption pump power of 31 W, corresponding to an optical conversion efficiency of 51.6%. To the best of our knowledge, this is the highest efficiency reported on the EO Q-switched laser by using RTP crystals.