Intracavity second-harmonic generation using a deuterated organic ionic crystal

A large organic ionic crystal (10×28×15 mm3):4-nitrophenol sodium(:Na) salt dihydrate (NPNa) crystal, which had good optical, mechanical, and thermal properties, was grown for the second-harmonic generation (SHG) device. Its effective nonlinear constant was found to be 5.0 pm/V at 1064 nm. The Vickers hardness and thermal conductivity were about two times larger than those of molecular crystals. The SHG device made of DNPNa, in which the water of crystallization of NPNa was deuterated, was used for the intracavity SHG of a diode-pumped cw Nd:YVO4 laser. High SHG power of 4.4 mW at 532 nm was obtained for the first time with an organic nonlinear material.