Numerical investigation of photonic crystal ring resonators coupled bus waveguide as a highly sensitive platform

Abstract

Optic and photonic sensing is a useful and novel technology for bio-sensing applications. In this paper, we have numerically designed and investigated sensitive photonic crystal ring resonators and three different structures of photonic crystal sensors are presented. The proposed sensors consist of ring resonators and bus and drop waveguides. These sensors are used to detect changes in the refractive index of the inner rod. Sensor 1 has one ring resonator between the bus and drop waveguides and has average sensitivity, quality factor, output power transmission, and detection limit of 278.5 nm/RIU, 3382, 90%, and 1.522 × 10−4 RIU, respectively. Sensor 2 has one ring resonator located above the bus waveguide and average sensitivity, quality factor, and detection limit of 231 nm/RIU, 4564, and 1.3 × 10−4 RIU, respectively. Sensor 3 has three ring resonators located between the bus and drop waveguides and has average sensitivity, quality factor, transmission, and detection limit of 228 nm/RIU, 5265, 81%, and 1.21 × 10−4 RIU respectively. The relationships of optical transmission, quality factor, and sensitivity with different wavelengths, and the resonant wavelengths with refractive index of inner rods are examined. Results from performing finite-difference time-domain simulations illustrate that the response of each detection shifts wavelengths according to the refractive index variations.