2ND-HARMONIC GENERATION BASED ON QUASI-PHASE MATCHING - A NOVEL CONFIGURATION

We consider the possibility of generating second-harmonic radiation by the interaction of two counterpropagating fundamental waves in a quas i-phase-matched second-order nonlinear medium in a waveguide. The conv ersion efficiency reaches a maximum at an optimum pump intensity. For a large range of pump intensities below a certain pump intensity the e fficiency is larger than that for the copropagating configuration. The saturation intensities at which the efficiency reaches 72% for poled KTiOPO4 and LiNbO3 can be achieved with lasers now available. (C) 1996 Optical Society of America