Tunability of the Terahertz Bandgap of One-dimensional Microplasma Photonic Crystals

Controlling the propagation of the terahertz waves is important for the application of terahertz technology. This work starts from Maxwell's equations and electron momentum conservation equations and derives the relative permittivity and conductivity of plasma. The feasibility of microplasma photonic crystal (MPPC) for terahertz band gap feature control is demonstrated in theory and simulation. The results show that, in flawless MPPC, when the electron density is lower than 1015 cm-3, the change of electron density has a negligible effect on the first terahertz band gap. When the electron density continues to rise from 1015 cm-3 to 1016 cm-3, the central frequency of the first forbidden band shifts 110 GHz to the high frequency. When the air pressure increases from 50.5 kPa to 202 kPa, the central frequency of the first band gap decreases from 0.871 THz to 0.79 THz. In MPPC with single defect, when the electron density increases from 1014 cm-3 to 1015 cm-3, the central frequency of narrow passband shifts about 24 GHz. It can be seen that the propagation of the terahertz wave can be tuned by the microplasma photonic crystals. © 2021, High Voltage Engineering Editorial Department of CEPRI. All right reserved.