CLASSICAL AND QUANTUM SIGNATURES OF COMPETING CHI((2)) NONLINEARITIES

We report the observation of the quantum effects of competing chi((2)) nonlinearities. We also report classical signatures of competition, n amely, clamping of the second-harmonic power and production of nondege nerate frequencies in the visible. Theory is presented that describes the observations as resulting from competition between various chi((2) ) up-conversion and down-conversion processes. We show that competitio n imposes hitherto unsuspected limits to both power generation and squ eezing. The observed signatures are expected to be significant effects in practical systems.