CONSERVATION LAW FOR MULTIPLE 4-WAVE-MIXING PROCESSES IN A NONLINEAR-OPTICAL MEDIUM

When two optical waves at frequencies omega1 and omega2 interact in a medium with cubic nonlinearity, multiple four-wave-mixing processes ca n generate pairs of sidebands. A conservation law that connects the am plitudes of the pump waves and sidebands is shown to arise from the Ma nley-Rowe relations and from the infinite set of conservation relation s of the nonlinear Schrodinger equation. The conservation relation is examined theoretically and verified experimentally for a variety of in put pump power levels and asymmetries. It can be used as a diagnostic measure to determine if nonlinearities of higher order than cubic are present.