Terahertz Refractive Index Sensor Based on Enhanced Extraordinary Optical Transmission

This paper presents a structure for refractive index sensors in the terahertz (THz) band. The THZ sensor is studied in simulation, utilizing the strong local electromagnetic field intensity produced by the enhanced extraordinary optical transmission. Depending on the different sensing positions of the sensor, their sensing basis is also different, such as Mie scattering, surface plasmon polaritons, etc. The sensing sensitivity based on Mie scattering can reach 51.56 GHz/RIU; meanwhile the sensing sensitivity based on surface plasmon polaritons is only 5.13 GHz/RIU. The sensor can also detect the thickness of the analyte, with the lowest detectable height of 0.2 µm. Additionally, we find that the sensitivity can be increased by replacing the silicon particle with the analyte.