Highly sensitive gas optical sensing in a multicavity based quasi-parity-time-symmetric structure

Abstract

A multicavity based quasi-parity-time (PT) symmetric structure is theoretically investigated for realizing highly sensitive gas detection. In the PT-symmetric broken phase, the singular pole effect can be achieved with much enhanced transmission, based on which low concentration of gas in the air can be efficiently sensed. In addition, the sensing signal is directly recorded by the change of the transmittance (T) of the sensor, real-time monitoring can be realized in our proposed structure. The sensitivities of -ΔT/ΔnD can reach 79437.2602 RIU−1 and 24753.7366 RIU−1 for benzene and methane, respectively. Such high sensitivity just occurs in the low concentration range. Our structures show great promise in constructing sensitive gas sensors to detect various harmful gases, such as volatile organic compounds (VOC) etc.

Keywords

• Parity-time-symmetric system
• Exceptional point
• Refractive index sensor
• Gas concentration detection
• Volatile organic compounds (VOC) monitoring