Design of highly sensitive refractive index sensor based on silicon photonic Mach-Zehnder interferometer

A highly sensitive refractive index sensor based on silicon photonic Mach-Zehnder interferometer is proposed. The device consists of a subwavelength-grating slot waveguide in one arm, as a sensing region, to enhance the light-gas interaction. By optimizing the structure parameters, the device operates near the dispersion turning point when the optical mode group velocity difference between the sensing arm and the other reference arm approaches zero. The RI sensitivity is 9.6 x 105/RIU and gas pressure sensitivity is as high as 232 nm/MPa. The study results show that the proposed design is a potentially robust refractive index sensor and has a good performance in gas pressure sensing.