Design and simulation of high-sensitivity refractometric sensors based on defect modes in one-dimensional ternary dispersive photonic crystal

Photonic crystals are widely used in sensors, lasers, optical wavelength filters, and dispersion compensations used in optical communication networks. We propose to exploit the defect modes of one-dimensional ternary photonic crystals based on silicon, analyte, and silica layers for a refractive index sensor. The defect modes are created by inserting an analyte layer in the middle of the structure between two adjacent silica and silicon layers. Exploiting the defect modes in the transmission spectrum leads to hypersensitivity. The results show that the thicknesses of the layers and defect part are, respectively, about 155, 700, 155, and 1200 nm in optimum conditions. Our optimum structure is about 11 mu m long, and sensitivity of this structure is more than 450 nm/RIU and 600 nm/RIU for the perpendicular light incident and incident angle of 45 degrees, respectively. The effect of dispersion is investigated on the sensor operation, too. Numerical simulations exhibit that sensitivity is decreased to 410 nm/RIU for incident perpendicular rays. Also, the optimum thickness of the defect layer is changed significantly when considering the dispersion effects, so dispersion plays a significant role in the proposed sensor. (C) 2019 Optical Society of America