Dual-parameter sensing of refractive index and pressure by dual-polarization microresonators

We propose a dual-polarization microring resonator that can simultaneously measure refractive index and pressure. Since the transverse electric (TE) mode and the transverse magnetic (TM) mode of a silicon waveguide have different energy distributions, TE and TM polarization have significant differences in sensitivity to environmental refractive index and pressure changes. Different responses to external refractive index and pressure changes can be obtained by simultaneously exciting TE and TM modes in a microring resonator. The refractive index sensitivities obtained in the experiment were 132.97 and 40.54 nm/RIU; the pressure sensitivities were 1.41 and 1.59 pm/KPa, respectively. By inversion of the second-order sensitivity matrix, it is verified that the effective refractive index and pressure response can be obtained simultaneously through a single measurement to realize the dual-parameter sensing of the surrounding refractive index and the pressure of the device structure.