High Q-factor MOEMS-2D photonic crystal dumbbell resonator for sensing force

Abstract

A high sensitive two-dimensional photonic crystal (2DPC) based resonator integrated with a microcantilever beam (MB) is reported for sensing force. Using the plane wave expansion method in the optiFDTD solver, the photonic bandgap is calculated. Using the FDTD approach, 2DPC is modeled and obtained transmission spectra at the through port and backward drop port. A high-quality factor is achieved in a dumbbell resonator, as it allows for light confinement to a greater extent than that in a ring resonator. Using finite element method (FEM) analysis, a MB built on a SOI wafer is modeled and the 2DPC dumbbell resonator is attached at the fixed end of the MB, to obtain high sensitivity. A point load is applied at the free end of the MB, and stress analysis is done, using the FEM. A change in applied force causes a change in stress distribution in 2DPC. The corresponding change in stress in 2DPC causes a linear shift in resonant wavelength (\(\lambda _{0}\)) in output ports. The linear variation of \(\lambda _{0}\) is correlated to a linear change in applied force. This sensor offers a minimum detectable force of 17.54 nN, a maximum Q-factor of 26390, a sensitivity of 3.42 nm/1 \(\mu\)N, and it delivers linear variation in the output parameters for a force range of 0–3 \(\mu\)N.