Tunable Fabry-Perot Filter Using Hybrid Integrated Grating and Slot Microstructures

The design, fabrication, and characterization of an electrostatically tunable optical Fabry-Perot (FP) filter with hybrid integration of grating and slot structures are presented. Using deep reactive ion etching, antireflection grating (ARG) structures are created at the inner wall of the FP resonator to enhance the performance of a tunable FP filter. The moving parts are released by etching the buried oxide layer using hydrofluoric acid vapor. The optical tuning range of the device is 19 nm. Attributed to the ARG structures, the light propagates effectively through the FP resonator. Thus, the Q-factor of the resonant peak is enhanced more than threefold when an FP resonator with ARG structures is compared with an FP resonator using one-slot (Si/air/Si) structure. With the optimized design, an FP resonator comprising of the ARG and two-slot structures shows record-breaking Q-factor, i.e., 9762.