The nonlinear-optical coefficients of RCOB (R = Gd, Y) crystals are measure
d. The spatial distribution of d(eff) (effective nonlinear-optical coeffici
ent) is subsequently determined. Our Experiments show that the maximum d(ef
f) occurs at the second quadrant. The second-harmonic generation efficiency
reaches 48% for a 6 mm long, (113.2 degrees, 47.4 degrees)-cut GdCOB, and
41.5% for a 5mm long, (113 degrees, 36.5 degrees)-cut YCOB, respectively. T
he intracavity frequency doubling of GdCOB is reported for the first time.