Abstract: The present invention relates generally to the field of optical devices and particularly to embodiments of a three-stage PPLN optical parametric oscillator/difference-frequency generator configuration. The present invention allows simultaneous generation of three wavelengths in efficient use of the pump signal. The structure of the first embodiment of the present invention comprises a first PPLN element having first and second grating regions, and a second PPLN element having its own grating period. An input coupler is positioned at the input and exit ends of a resonator cavity and the first PPLN element is positioned between the input coupler and the second PPLN element. A second embodiment of the present invention includes a single PPLN element having three separate grating regions. The single PPLN element is positioned between input and output coupler mirrors. A third embodiment of the present invention includes a single PPLN element having three grating regions.

Abstract: The present invention relates generally to the field of optical devices and particularly to embodiments of a four-stage PPLN optical parametric oscillator/difference-frequency generator configuration. The present invention allows simultaneously and colinear generation of four wavelengths in efficient use of the pump signal. A first embodiment comprises a singly resonant cavity having an internal monolithic non-linear optical medium disposed in the cavity. The cavity is bounded by an input mirror and an output mirror. The monolithic non-linear optical medium is divided into four regions each having its own grating period. A second embodiment of the present invention comprises a monolithic non-linear optical medium divided into four separate regions. The entrance facet and exit facet of the monolithic non-linear optical medium includes a coating which acts as the cavity mirrors.