Tunable Photonic Band Gaps in One-Dimensional Magnetized Cold Plasma Photonic Crystals Using the Transfer Matrix Method

Abstract

Plasma represents the fourth fundamental state of matter, characterized by the collective interaction of free electrons, ions, and neutral particles under long-range Coulomb forces. Unlike conventional thermodynamic phase transitions, the transformation from gas to plasma occurs gradually through ionization at high temperatures or under electromagnetic excitation. In this work, the optical behavior of a one-dimensional periodic structure composed of alternating layers of air and magnetized cold plasma (MCP) is theoretically investigated. The dielectric response of the plasma medium is derived using Maxwell’s equations, incorporating the effects of plasma frequency, cyclotron frequency, electron density, collision frequency, and externally applied magnetic field. The refractive index of the plasma layer is obtained from its frequency-dependent permittivity, and the photonic band structure and transmittance characteristics are analyzed using the Transfer Matrix Method (TMM). The results reveal that both right-hand and left-hand polarizations exhibit tunable photonic band gaps in the microwave and GHz frequency ranges. It is observed that the external magnetic field and plasma density play dominant roles in shifting band edges and controlling transmission windows, while the effective collision frequency has a comparatively weak influence. The proposed plasma photonic crystal demonstrates reconfigurable broadband reflection and narrow-band filtering behavior, highlighting its potential application in tunable microwave and terahertz photonic devices.