Plasmonic semiconductor-based interferometers for ultrasensitive THz biosensing

A novel plasmonic Mach-Zehnder interferometer (MZI) biosensor, which is based on a simple slit-groove microstructure, is reported in the terahertz (THz) regime. The permittivity-sensitive phase difference between the two propagating SPPs waves gives rise to the modulation of the transmitted intensity. The results show that the MZI biosensor possesses a sensitivity as high as 140000 nm/RIU (refractive index unit). The highly compact configuration may find important applications in areas of sensing and integrated THz circuits (ITCs).