ANALYSIS OF POWER-DEPENDENT SWITCHING BETWEEN RADIATIVELY COUPLED PLANAR WAVE-GUIDES

Effective coupling between two remote optical waveguides without branc hing sections can be achieved in a three-guide system with multimode c entral waveguide, We investigate the nonlinear power switching of cw, laser radiation by such radiatively coupled waveguides, It is shown th at effective all-optical switches with spatially well separated input/ output channels can be realized although the influence of multimode in terference on the switching characteristics becomes more pronounced fo r increasing thickness of the central guide. Different coupling regime s are specified, and the changes in switching characteristics during t he transformation from one regime to another is studied, Numerical cal culations for the critical power are compared with an approximate anal ytical expression, It Is also shown that, at a moderate input power, a small number of modes determines the switching behavior.