Single-frequency continuous-wave optical parametric oscillator

A single-frequency continuous-wave optical parametric oscillator, characterized by comprising a pumping source, a focusing lens, a resonant cavity, an optical parametric down-conversion crystal, and a birefringent crystal;

• wherein a polarization direction of a pump light provided by the pumping source is horizontal polarization;
• the resonant cavity comprises a concave-convex lens, an output planoconcave lens and at least two transitional planoconcave lenses arranged between the concave-convex lens and the output planoconcave lens, a waist spot of the pump light obtained by the focusing lens is located between the concave-convex lens and a first transitional planoconcave lens adjacent to the concave-convex lens on an optical path, and a center of the optical parametric down-conversion crystal coincides with the waist spot of the pump light;
• and
• the birefringent crystal is located at a beam waist between the output planoconcave lens and a second transitional planoconcave lens adjacent to the output planoconcave lens on an optical path, and the birefringent crystal adopts critical phase matching or non-critical phase matching so as to generate frequency-doubled light;
• a signal light generated by the optical parametric down-conversion crystal resonates in the resonant cavity, and the pump light, the idler light generated by the optical parametric down-conversion crystal, and the frequency-doubled light generated by the birefringent crystal pass through the resonant cavity in a single pass.