Green light has been observed for the first time to the authors' knowledge by bulk phase-matched second-harmonic generation from a stretched main chain polyurea. The polyurea was synthesized from 4,4'- diphenylmethane diisocyanate and 4,4'-methylene bis(cyclohexylamine). The spin-coated film has an initial positive birefringence. Drawing further increased the birefringence, and the film can be used for phase matching just as in biaxial single crystals. The drawn and poled polymer films belong to the 2<i>mm</i> point group. Three independent nonlinear-optic coefficients were determined. The type I phase-matching characteristics were calculated and confirmed by experiments. We demonstrate that a highly effective second-harmonic-generation device with a long optical path length can be obtained by use of bulk phase-matchable poled polymer.
© 1995 Optical Society of America
X. T. Tao, T. Watanabe, D. C. Zou, H. Ukuda, and S. Miyata, "Phase-matched second-harmonic generation in poled polymers by the use of birefringence," J. Opt. Soc. Am. B 12, 1581-1585 (1995)