Dual Fano-type Resonance Based Refractive Index Sensor using 2D Silicon Photonic Crystal Waveguide-Cavity System

In the present paper we have proposed a refractive index sensor created on the platform of a two-dimensional photonic crystal. The proposed device is based on dual Fano-type (asymmetric) resonance which is evident from the obtained spectral response with two peaks, one very sharp, while, the other very broad. The plane wave expansion method is used to calculate the band structure of the sensor and the two-dimensional finite difference time domain method is used to analyse the performance of the sensor. The band diagram shows that the structure allows only TE wave propagation. The sensitivity of the proposed sensor has been gauged by varying the background refractive index insteps of 0.01 within the range of 1.00-1.04 and found to be . The quality factor and the figure of merit are found to be 2000.5 and 600 RIU-1 respectively. The broad peak exhibits larger redshift compared to the sharp peak with variation in background refractive-index. The sensor is compact in size allowing for its on-chip implementation.