Asymmetric semiconductor waveguide with defocusing nonlinearity

A novel nonlinear waveguide structure capable of implementation in multiquantum well material is analyzed. It is shown that the defocusing nonlinearity associated with the fundamental absorption edge of semiconductor material imposes a basic design requirement on the waveguide structure. Results for a specific structure designed for operation at a wavelength of 1.55 μm show a form of optical limiter action which, for representative values of the semiconductor nonlinearity, is found to be operative at about 100 μW of launched optical power. It is concluded that practical device implementation of the effects described will require consideration of the tradeoff which arises between attainable optical nonlinearity and acceptable optical absorption in the structure