Tunable Mid-Infrared Nanoscale Graphene-Based Refractive Index Sensor

A nanoscale refractive index sensor comprising of input-output graphene parallel plane waveguides coupled through a resonator is proposed. Operating as a wavelength selective structure in mid-infrared region, the sensor performance is based on the variation of the resonance wavelength of the structure. The simulation results obtained by numerical method of the finite difference time domain reveal linear dependency between the resonance wavelengths and the refractive indices of the material injected into the coupling resonator of the sensor, predictable by the resonance criterion of the resonator. The wavelength resolution of the detection system determines the overall sensor resolution. To utilize voltage dependency of graphene chemical potential, the wavelength range of the performance of the sensor can be tuned appropriately. The proposed sensor can be used as a platform for design of the sensors utilizing in various chemical and biomedical systems.