Phase and Wavelength Sensitivities of Optical Refractive Index Sensor Based on Fano Resonance

An optical refractive index sensor with a metal-multilayer dielectric film structure based on Fano resonance (FR) is proposed to solve the low sensitivity of traditional surface plasmon resonance (SPR) sensors. The sensor’s performance can be optimized, and a plasmon-induced reflection (PIR) of incident light can also be achieved by adjusting the thickness of each layer. Through an innovative experimental design, the practical measurement phase sensitivity of the sensor based on FR is achieved for the first time, which provides a reference for subsequent theoretical research and experimental preparation. The wavelength sensitivity and the phase sensitivity can reach 345 nm/RIU and
$4.00\times 10^{{5}\circ }$
/RIU, which experimentally proves that phase interrogation has higher sensitivity than traditional wavelength interrogation. The sensor can be a promising candidate for exploiting novel plasmonic sensors with ultrahigh sensitivity and resolution for biosensing applications.