Study On All-solid-state CW Green Laser Of LD Pumped Nd:YVO₄/PPLN

A compact and highly efficient 808nm LD pumped Nd:YVO4/PPLN continuous wave green laser is designed based on the quasi-phase matching frequency doubling technique, since the current LD pumped all-solid-state green lasers have the shortcomings of complex structure, high cost, inconvenience of operation and low conversion efficiency, etc. Stable green laser outputs have been achieved and the output characteristics are experimentally investigated. The contents are concluded as follows:1、The working principles, structural designs and their technical features of the diode-pumped all-solid-state lasers are summarized. Based on it, the development history, current research status and the typical applications of LD pumped green lasers are introduced in emphasis;2、Several laser crystals and nonlinear crystals are introduced and compared. The thermal effect in Nd:YVO4 and the temperature induced optical refractive index change of PPLN are also studied;3、The optical frequency doubling properties in PPLN, the thermal effect in Nd:YVO4 and the effect of laser cavity parameters on its output performance are numerically analyzed based on the nonlinear coupling wave equation and laser cavity theory;4、A compact and highly efficient linear cavity of CW green laser has been designed based on Nd:YVO4/PPLN crystal. The experimental results show that when pump power is set at 4.1W, the CW green light output power of 1.343W is achieved with the corresponding optical-optical conversion efficiency of 32.8%. Controlling the pump power at about 3.33W,the fluctuation of the output power within 2 h is less than 5%. Furthermore, a stable and highly efficient "V" shape cavity CW green laser has been designed by introducing a flat concave mirror with the curvature radius of 100 mm. The experimental results show that when pump power set at 4W, the CW green light output power of 1.6W is achieved with the corresponding optical-optical conversion efficiency of 40%. Controlling the pump power at about 3.33W, the fluctuation of the output power within 2 h is less than 3%. Finally, the output characteristics of the two kinds of laser cavities are analyzed and compared.