A reconfigurable self-collimation-based photonic crystal switch in silicon

We present a reconfigurable, compact, low loss, optical switch in silicon. The device utilizes the self-collimation properties of photonic crystal structures and provides a technique for efficiently switching an electromagnetic wave guided through a pre-engineered dispersion based photonic crystal self-guiding structure. The electromagnetic wave can be either in the microwave or optical regime based on the constituent materials and dimensions of the photonic crystal host. We propose that the "loss tangent" of dielectric material in the switching region can be modified by external "commands" to control the direction of propagation of the self-collimated signal and hence attain switching, thereby redirecting the light. Based on the geometrical orientation and position of the applied electric field, electromagnetic waves can be completely redirected (switched), or partially routed towards any arbitrary direction on a Manhattan grid or network. We have found that the induced loss does not significantly attenuate the waves switched in any direction. The structure presented can be generalized to an arbitrary N by M interconnected switching network or fabric, where the switching topology can be dynamically modulated by the application of external fields. To attain switching, the free-carrier absorption loss of Si is controlled by carrier injection from forward-biased PN junction. The concept device is designed and analyzed using the FastFDTD (TM) accelerated hardware based FDTD technology.