Effect of dielectric plate on terahertz wave propagation in microplasma

The scattering matrix method is used to study the propagation properties of terahertz (THz) waves in microplasma with dielectric plates. The effects of physical parameters such as the material and thickness of the dielectric layer, the thickness of the microplasma, the electron density, and the collision frequency on the propagation characteristics of THz waves are analyzed. The results show that the reflectivity, transmissivity, and absorptivity of THz waves exhibit approximately periodic oscillations with frequency when the permittivity of the dielectric plate is considered. As the permittivity of the dielectric plate increases, the amplitude of the oscillations increases. The oscillation periods in the reflection and transmission spectra of THz waves are significantly decreased when the thickness of the dielectric plate increases, but the maximum reflectivity and minimum transmissivity remain nearly constant in a single period. Additionally, the thickness and collision frequency of the microplasma significantly affect the near-periodic oscillations depicted in the diagrams. The electron density of the microplasma affects lower frequency THz waves more than higher frequency (above 1 THz) ones. These may assist in developing plasma photonic crystals or modulating THz waves.