CRYSTAL-GROWTH AND THE NONLINEAR-OPTICAL PROPERTIES OF 4-NITROPHENOL SODIUM-SALT DIHYDRATE AND ITS DEUTERATED MATERIAL

Large organic ionic crystals on the order of a few centimeters of 4-ni trophenol sodium(:Na) salt dihydrate (NPNa) and DNPNa, in which the wa ter of crystallization of NPNa was deuterated, were grown for second-h armonic generation (SHG). The Vickers hardness and thermal conductivit ies of NPNa were about two times larger than those of conventional org anic molecular crystals. The effective nonlinear optical constants of NPNa and DNPNa were estimated to be 5.0 and 5.5 pm/V, respectively. Th e optical loss coefficients, measured by spectrophotometry, of NPNa an d DNPNa were 1.8 and 0.6 dB/cm at 1064 nm, respectively. The substitut ion of D2O for H2O in NPNa crystal is very effective in reducing the o ptical loss coefficient. High power of 4.4 mW green SH light was obtai ned using a 1.5-mm-thick DNPNa crystal as the intracavity SHG device o f a diode-pumped Nd:YVO4 laser.