Photonic Crystal All‐Optical Switches

Currently, almost all communicated information is based on optical signals due to their very high bit rate data transmission and large bandwidth. Photonics has played a key role in this advancement as it provides enhanced light-matter interaction to control the optical signals for a desired application. All-optical switches (AOS) provide highly efficient data transmission as it does not need to convert the optical-electrical/electrical-optical signal at the interfaces and so minimizes power consumption and further increases operating speed. AOS for use in future technology needs to be ultra-compact for its integration with other optical devices. For switching operation to meet the increasing demand for high data rate, bandwidth, low loss, reduced power consumption, photonic crystal (PhC)-based AOS has been designed. PhC-based AOS possess nanocavity with a high Q factor and very small mode volume. In this nanocavity, light and the material interact very strongly and so with minimal switching energy one beam can be used to change the direction of another beam, thus working as an efficient AOS. Basically, the pumping beam changes the refractive index of the material in the cavity, which in turn affects the direction of the flow of light through it, and hence provides the desired switching operation. This enhanced light-matter interaction is possible in various ways such as using nonlinear material or plasmonic materials, which will be discussed in detail in the following chapter, as well as the fabrication issues and limitations associated with AOS based on PhC.