Thermal Effects in Ultrafast Photonic Switches

The performance of a nonlinear device may be significantly altered by thermal effects. The heat generated by the absorption of power from the switching laser can induce thermal index changes which may overwhelm the photonic index changes. Here a model of these thermal effects is presented, and expressions for the relationship of thermal to photonic index changes are derived. Previous workers have considered heating due to a single pulse.1 Our treatment snows that, for the appropriate material and device parameter ranges, cumulative thermal build-up will be important in the envisioned high-data-rate systems. Using these results, we compare the potential performance characteristics of various materials, including experimental heavy-metal glasses which show large nonlinear effects.