EFFICIENT INTERNAL OPTICAL PARAMETRIC OSCILLATION

Abstract

Efficient internal optical parametric oscillation has been obtained using a LiNbO₃ crystal inside the resonator of a continuously pumped repetitively Q‐switched 1.06μ Nd:YAG laser. Dielectric mirrors are coated directly on the plane‐parallel end faces of the crystal, and no focusing optics are used inside the laser. The oscillator operates near degenerate with outputs near 2μ. Average output powers as high as 350 mW and 75 % depletion of the available pump power are observed. This represents an order of magnitude larger output power than previously reported for a parametric oscillator. Internal oscillation causes stretching of the laser pulses to as much as five times the normal length, with corresponding increases in oscillator pulse length. Operation of this internal oscillator is compared to that of a similar external oscillator pumped by the same laser.