OPTICAL NONLINEAR DEVICES

A group of devics are set forth that individually employ a transparent nonlinear dielectric element, such as a piezoelectric crystal, in the cavity of a laser. The crystal serves to generate harmonics of the frequency generated by the laser. The light energy whose frequency is to be converted is retained in the laser cavity and the electric field within the cavity builds up to high values. The conversion efficiency is high because the harmonic electric field is proportional to the square of the fundamental electric field.