Angle-Selective Photonic Crystals for Multi-Physical Sensing Applications

This study reports a high-transmission photonic crystal (PC) that was optimized for TM waves at a frequency of 43.8 GHz and engineered using photonic band gap (PBG) principles to achieve angle selection. The structure demonstrated a remarkable transmission from -68° to 0°, consistently exceeding 80% efficiency. Assessing the fragility of the medium within the PC using the critical angle, a multi-physical sensor (MS) comprising both refractive index sensing (RIS) and plasma density sensing (PDS) functions was proposed. The PDS could detect concentrations from 0.4 × 10