Non-critical phase-matched second harmonic generation in GdxY1-xCOB

We have characterized non-critical phase-matching (NCPM) for both Type I and Type II second harmonic generation (SHG) in y-cut GdxY1-xCOB using a nanosecond optical parametric osciilator (OPO). The variation of the NCPM wavelength with temperature was investigated for different values of the compositional parameter x. Efficient SHG of 1064 nm was achieved by choosing the suitable compositional parameter x = 0.28 and by tuning the temperature of the crystal to 52 degreesC. Using a 25-mm-long Gd0.28Y0.72COB crystal, conversion efficiencies of 41 and 43% were obtained respectively from a mode-locked Nd : YAG and a Q-switched Nd : YAG laser