Refractive index biosensor using sidewall gratings in dual-slot waveguide

This paper presents an optical biosensor using sidewall grating in dual slot waveguide, modeled on silicon-on-insulator (SOI) platform. By optimizing the geometric parameters of the device, the spectral response is tailored to obtain a sharp resonant peak with high transmissivity that also enhances the limit-of-detection. The device detects the shift in resonant wavelength on a variation of the biomaterial refractive index. The simulation study has performed using the transfer matrix method. The obtained characteristics of the sensors include linear response to a change in refractive index of biomaterial, limit of detection of the order of 10−6 and ease of fabrication. The device performance has also compared with other SOI resonator structures like photonic crystal waveguide, sub-wavelength grating, ring resonator and grating resonator.