We analyze the operation of a tunable device that is composed of two channel waveguides that are fabricated on a nonlinear substrate and of two adjacent electrodes, where the evanescent fields of the two guided modes overlap. The optical power-dependent propagation constant of the guided modes is modified locally as the power leaks from one channel waveguide to the other, resulting in a continuous change in the local phase matching. We present a general expression for the operation of the device together with a numerical example that demonstrates that the device acts as an all-optical gate, discriminator, and limiter, having a speed that is limited only by the transit time along the channels and the response time of the material.
© 1982 Optical Society of America
Dror Sarid and Murray Sargent III, "Tunable nonlinear directional coupler," J. Opt. Soc. Am. 72, 835-838 (1982)