Electrical tuning of the silicon-based 2-D photonic bandgap structures

Abstract

Silicon-based 2-D photonic bandgap (PBG) structures have an unmatched potential for integration with well-established microelectronic devices and circuits. They can allow for compact optical devices with enhanced functionality and performance. While a number of passive PBG silicon-based devices have already been demonstrated, electrical tuning of their properties has yet to be implemented. PBG tuning can be achieved by replacing the air inside the device with active optical material, for example liquid crystals (LCs) or an electro-optic polymer. The two main requirements necessary for tuning in PBG structures are (i) the electric field of the control signal should be present inside the active optical material to modify its properties, and (ii) the energy of the optical mode of interest should be distributed inside the active material. While the latter condition can be satisfied by proper optical design, the former requirement is difficult to satisfy due to external electric field screening by the conductive silicon walls. In this work, an analysis of this effect is conducted and guidelines to overcome screening and thus allow for switching are suggested. Further, by using LCs as an active optical material, electric field switching in 2-D silicon-based PBG structures is demonstrated for the first time. Results of this work can lead to the development of silicon-based switches, active routers and filters for future optical interconnects.