Effective third harmonic generation of 355 nm ultraviolet laser based on the borate-phosphate Ba3(ZnB5O10)PO4 crystal

An effective third harmonic generation (THG) 355 nm laser in a novel Ba3(ZnB5O10)PO4 (BZBP) crystal was demonstrated. Based on the phase matching (PM) calculation, the BZBP crystal has the type-I PM angle of theta = 90 degrees, phi = 73.2 degrees for generating the THG 355 nm laser, with a large acceptance angle of 66.3 mrad center dot mm and a small walk-off angle of 6.06 mrad. Using a nanosecond 1064 nm laser as the pump source, the THG 355 nm laser could achieve the maximum conversion efficiency of 28.4%, and the highest output power of 0.56 W. In addition, BZBP crystal also has a small weak absorption coefficient of 20-40 ppm/cm and a laser damage threshold of 1.04 GW/cm2. The achieved results indicate that the BZBP crystal is a promising UV nonlinear optical material due to its short absorption edge (180 nm), small walk-off effect, large acceptance angle, and non-hygroscopicity.