ELLIPTIC-FOCUSING EFFECT ON PARAMETRIC OSCILLATION AND DOWNCONVERSION

A theoretical study is presented that enables the calculation of the o ptimal focusing parameters in a singly resonant optical parametric osc illator and difference-frequency generation with elliptical foci. The effect of diffraction, phase matching, beam walk-off, and resonator as tigmatism are included in the model. The results show that an optimal focusing configuration is obtained with unequal confocal beam paramete rs and that an elliptical beam profile can substantially increase the conversion efficiency when beam walk-off is present in the crystal. (C ) 1998 Optical Society of America.