Design and simulation of a tunable photonic band gap filter

A tunable photonic band gap (PBG) filter is designed. A one-dimensional photonic crystal (1-D PC) is comprised of alternate dielectric layers of polydimethylsiloxane (PDMS) and Si. A comb-drive microactuator is designed to compress the 1-D PC along the axis of dielectric stack and tune the PBG. Due to large stiffness difference between Si and PDMS, only the PDMS layers are subjected to dimensional change during compression. We plot the 3-D PBG map that shows wide tuning range of central pass-band wavelength of around 100 nm in visible region. Dependency of the PBG on the angle of incidence is investigated by a propagation matrix method, and the method shows gradual variation of the PBG for both s-wave and p-wave. The angle of incidence of 10° is chosen for the design so that the PBGs for both s-wave and p-wave are about the same. Therefore, the PC can still reflect all incident lights within the PBG.