Nd:YAG microchip laser frequency doubling with periodically poled and conventional type Ⅱ KTP crystals

摘要

Fundamental 1064 nm wavelength radiation of a diode pumped passively Q-switched Nd:YAG microchip laser was frequency doubled by periodically poled (PP) and conventional type Ⅱ KTP crystals. Second harmonic (SH) conversion efficiency of 60% and 47% has been achieved with PPKTP and KTP crystals, respectively. SH pulse energy of as much as 6μJ, at 900Hz repetition rate, has been obtained for 10 μJ pulse energy of the input 1064 nm radiation focused with a waist radius of 25 μm inside the 8 mm long PPKTP crystal. We estimated an effective nonlinear coefficient of 6.9 pm/V and a thermal acceptance FHWM bandwidth of 5.78℃ for the PPKTP sample.