Abstract
On-chip optical gas sensors, which use resonant shifts of cavities to detect molecular concentrations, have the advantages of high sensitivity, real-time detection, and compact footprint. However, such sensors are usually limited by a serious cross-sensitivity issue induced by environmental temperature variations. To overcome this limitation, we study a dual-mode graphene-on-microring resonator to accurately measure gas concentrations without suffering from temperature variations. To be specific, the influences of gas-induced graphene’s optical conductivity changes and environmental temperature variations on effective refractive indices of TE0 and TE1 modes in the resonator can be decoupled based on the modal linear independent responses. With this method, we designed a nitrogen dioxide sensor with a sensitivity of 0.02 nm/ppm and a limit of detection of 0.5 ppm. Our study paves the way for developing on-chip optical gas sensors with excellent sensitivity and temperature stability.
Highlights
Compact and low-cost gas sensors have wide applications in consumer electronics, industrial safety, medical diagnosis, environmental monitoring, vehicle exhaust measurement, and public security
We theoretically analyzed the influences of gas-induced graphene’s optical conductivity changes and environmental temperature variations on effective refractive index (RI) of the TE0 and TE1 modes in the graphene-on-microring resonators (MRRs)
Our study shows that graphene and temperature-induced RI variations can be extracted separately due to the modal linear independent responses to these two factors
Summary
Compact and low-cost gas sensors have wide applications in consumer electronics, industrial safety, medical diagnosis, environmental monitoring, vehicle exhaust measurement, and public security. J. Wang et al.: Design of Dual-Mode Graphene-on-Microring Resonator for Optical Gas Sensing devices, gas molecules in the ambient environment alternate the RI of a waveguide, resulting in a phase change of the optical mode. We studied a dual-mode graphene-on-MRR RI gas sensor to overcome the cross-sensitivity problem.
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