Design and analysis of an elliptical-shaped ring resonator for photonic crystal temperature sensing

This paper presents the design and analysis of a temperature sensor that utilizes an optical filter consisting of an elliptical-shaped photonic crystal ring resonator (E-PhCRR) in a two-dimensional configuration. The basic structure comprises silicon (Si) rods immersed in the air (disconnected structure) arranged in a triangular lattice. The newly designed structure’s photonic band gap (PBG) was calculated using the plane wave expansion (PWE) method, and the temperature sensor was modeled and studied using the finite difference time domain (FDTD). The temperature change causes a redshift in the resonance wavelength due to the subsequent change in refractive index. The temperature was systematically adjusted within the range of 0 °C to 50 °C, leading to a discernible change in the resonant wavelength by 5.2 nm, shifting it from 1682.59 nm to 1687.79 nm. The elliptical shape of the photonic crystal ring resonator provided us with significant flexibility to attain improved outcomes. Specifically, we achieved a quality factor of 316200, a temperature sensitivity of 103.92 pm/°C, and a refractive index sensitivity of 443 nm/RIU. Furthermore, we were able to acquire a detection limit of \(5.12 \times 10^{-9}\) $5.12\times {10}^{-9}$ RIU while maintaining a compact size of \(116.5 \upmu {\text{m}}^{2}\) $116.5\mathrm{\mu }{\text{m}}^2$ .