Optimization of the quality factor and sensitivity of one-dimensional photonic crystal methane sensor with cryptophane A cavity

Abstract

In this work, we introduce a sensor for measuring different methane concentration levels. The model is based on a defective one-dimensional photonic crystal composed of alternating layers of air and Silicon with a cryptophane A cavity. We assume that the refractive index of silicon depends on temperature. The transmittance spectrum was calculated using the transfer matrix method. This work also assessed the effects of temperature and methane concentration on the wavelength shift of a localized mode within the photonic band gap. The results show the shift of this localized mode toward longer wavelengths as temperature increases, with the quality factor reaching its maximum value at around 8994.35. When maintaining a constant temperature, we observed a blue-shift when the methane concentration is in a range of 0.0–3.5%, and the quality factor decreases to 6358.26, with a maximum sensitivity of 144.485 nm by RIU. Due to its excellent performance to store energy within the cavity, this sensor can be used to detect different gas concentrations.