An indium tin oxide metasurface filter for terahertz applications: Design, fabrication, and characterization

In this paper, using a cross-shaped complementary Indium Tin Oxide (ITO)-based meta surface design, the transmission of THz radiation is shown to be filtered within the 3 dB level from maximum in the frequency range of interest 333 GHz). Various metasurface structures primarily composed of cross-shaped openings with a 400 micron unit cell size are patterned on top of 1750 micron thick fused silica substrates. They are patterned using UV lithography methods after the films were grown using DC sputtering. The fabricated structures were characterized using Terahertz Time Domain Spectroscopy (THz-TDS) measurement technique. The measured transmission agrees well with the simulation of the structure for four different samples with different geometries. These results suggest that metasurface and/or metamaterial patterns based on ITO in visibly transparent media can be utilized for filtering of frequencies in the long wavelength spectrum. These types of filters can be very useful in the near future for THz communication and security applications.