Direct thermal tuning of the terahertz plasmonic response of semiconductor metasurface

In this study, the tunable depth of an array of semiconductor indium antimonide (InSb) subwavelength strips was studied by isothermally increasing the intrinsic carrier density, and then increasing the plasma frequency and the dielectric constant in the terahertz (THz) regime. It could be found that the tunable depth can attain 79.07% and the quality factor Q can be up to 7.1 in the window between 0 and 1.2 THz from 450 to 250K. In order to improve the performance of the device, the strip array of semiconductor InSb on a ferroelectric strontium titanate film was also investigated. The results showed that when the temperature varied from 450 to 250K, the modulation depth increased and attained 84.06%. These findings would facilitate the design of tunable components in the communication region of the THz regime.