Tunable high-Q photonic-bandgap Fabry-Perot resonator

We report a theoretical analysis of a two-dimensional silicon photonic-bandgap (PBG) structure with ten layers of air-filled circular holes and an air-filled line defect, to function as a Fabry-Perot (FP) resonator. Using a multiple propagation series method, our calculations have shown a group of nine or ten resonant peaks of high-quality-factor Q(>2000) and of equal spacing (>80 nm) between two photonic bandgaps. The resonant peaks have large tunability in wavelength by varying the incident angle of light, which can be continuously tuned from 1.23 to 2.08 µm. The Q values of the resonant peaks increase linearly at small incidence and sharply at large incidence. For a lossy medium, the Q values may decrease significantly at large incidence angles, but resonant frequencies are relatively unchanged. The applications of the proposed PBG FP resonator for wavelength-division-multiplexed optical communications are discussed.