BICHROMATIC FREQUENCY-CONVERSION IN POTASSIUM NIOBATE

Two frequency components of an IR laser beam near 980 nm are simultane ously coupled into two adjacent longitudinal modes of a passive ring r esonator. A potassium niobate crystal inside the resonator converts th e circulating LR light into coherent blue radiation. The total convers ion efficiency is enhanced by a factor of 1.4 compared with that of co nventional single-mode intracavity second-harmonic generation with the same circulating total power, and we obtain a total output power of 5 60 mW from 780-mW LR light incident upon the cavity. The spectra of th e generated blue radiation and the circulating IR light contain a numb er of equidistant frequency components that are due to consecutive sum -and difference-frequency mixing. (C) 1998 Optical Society of America.