Experimental evidence of spontaneous symmetry breaking in intracavity type II second-harmonic generation with triple resonance

摘要

We describe a spontaneous symmetry-breaking phenomenon between the intensities of the ordinary and extraordinary components of the fundamental field in intracavity type II harmonic generation. It is based on a triply resonant cavity containing a type II x~(2) crystal pumped at fundamental frequency ω_(0). The pump beam generates a second-harmonic mode at frequency 2ω_(0) that acts as a pump for frequency-degenerate type II parametric downconversion. Under operating conditions symmetric with respect to the ordinary and extraordinary components of the fundamental wave, we show a breaking of the symmetry of the intensities of these two waves.