High-Efficiency Mid-Infrared Transmission Modulator Based on Graphene Plasmon Resonance and Photonic Crystal Defect States

With the continuous exploration and advancement of communication frequency bands, terahertz and mid-to-far-infrared communication systems have attracted significant attention in recent years. Modulators are essential components in these systems, making the enhancement of modulator performance in the infrared and terahertz bands a prominent research focus. In this study, we propose a high-performance infrared transmission-type modulator based on the plasmon resonance effect of graphene nanoribbons. This design synergistically exploits near-field enhancement from metal slits and defect states in one-dimensional photonic crystals to strengthen light–graphene interactions. The modulator achieves a modulation depth exceeding 80% and an operating bandwidth greater than 4 THz in the mid-infrared range, enabling efficient signal modulation for free-space optical communication. Importantly, the proposed design alleviates experimental challenges typically associated with the need for high graphene mobility and a wide Fermi energy tuning range in conventional approaches, thereby improving its practical feasibility. Moreover, the approach is scalable to far-infrared and terahertz bands, offering valuable insights for advancing signal modulation technologies across these spectral regions.