Observation of Biexcitonic Optical Bistability and Optical Limiting in CuCl

Abstract

Experimental evidence for the occurrence of optical bistability using the biexciton two-photon resonance in CuCl is presented. These observations agree with recent theoretical predictions that require an intensity of 10 MW/${\mathrm{cm}}^{2}$ and 10-\ensuremath{\mu}m-thick etalons with 90% reflective coatings. Earlier much less demanding predictions neglected two important physical effects: unsaturable background absorption at the biexciton from the tail of the exciton resonance and broadening of the biexciton resonance with intensity.