ROLE OF THE ASYMMETRY IN A 3RD-ORDER NONLINEAR DIRECTIONAL COUPLER

The behaviour of an asymmetric third-order nonlinear directional coupl er is discussed. The operation of such devices is strongly influenced by the choice of the channel for the input, the linear or the nonlinea r one. When input linear excitation is considered and no saturation is present in the other nonlinear arm, a power switch in a half-beat len gth coupler with excellent functional characteristics is found. When s aturation is included, the initial excitation in the linear core gives a critical nonlinear saturation value to achieve effective power swit ching larger with respect to the nonlinear core input excitation.