Terahertz Metamaterial Waveguide with I-Shaped Resonators for Phase and Absorption Modulation

In terahertz communication systems, amplifiers and other components can induce non-linear distortion in terms of amplitude and phase, resulting in system performance degradation. This paper presents a terahertz metamaterial waveguide to mitigate amplitude and phase distortions in some terahertz systems. A simple method based on free-space analysis is proposed for designing metamaterial waveguides in an enclosed space. The quasi-periodic metamaterial structures, which feature I-shaped resonant patterns, are integrated onto the inner walls of rectangular waveguides. The phase and amplitude of electromagnetic waves within the waveguide can be modulated by varying the dimensions and number of these resonators. Utilizing the effective medium theory and the equivalent circuits, the metamaterial waveguide's phase and absorption modulation mechanisms are analyzed. Based on the proposed structure, a metamaterial waveguide with I-shaped resonators is designed and fabricated, and its abilities to modulate the phase and absorption of terahertz waves around 0.2 THz are demonstrated.