Cross talk between bistable elements on an InSb étalon

Abstract

Cross talk due to transverse carrier diffusion between identical bistable elements on an InSb étalon at 80 K is studied both theoretically and experimentally. Measurements of cross talk between two such elements show that typically, for a practical system, a critical separation of a few diffusion lengths between beam centers is necessary for independent operation. When the difference between holding and switching powers approaches zero, the results show that the critical distance diverges. Delays as great as 4 μsec have been observed when one element is switched and its neighbor is induced to switch through the cross-talk mechanism. These delays can be partially attributed to critical slowing down, and, in principle, they diverge as the interelement distance is increased toward the critical separation. A theoretical model based on the diffusion equation for the single-pass nonlinear phase shift shows how the critical separation depends on physical parameters and the number of elements forming an array. We found that the relevant interaction is essentially limited to nearest neighbors. When the theory is applied to two bistable elements, good agreement is obtained with the experiments in both the steady and the dynamic states.