Tunable subwavelength terahertz plasmonic stub waveguide filters

Tunable subwavelength terahertz (THz) plasmonic stub waveguide filters based on indium antimonide are proposed and numerically investigated for the first time. The transmission line theory and the finite different time domain simulation results reveal that the single-stub waveguide structure can realize a stop-band filtering function and the central wavelength of the notch is linearly dependent on the stub length while nonlinearly dependent on the stub width. The central wavelength of the notch can be actively controlled by tuning the temperature. As an extension to the single-stub structure, multiple-stub InSb slot waveguide structures are also proposed and used to realize a wide stop-band filtering function. The proposed filters may have applications in THz highly integrated plasmonic circuits.