High-Q edge-state engineering in 1D plasma photonic crystals for advanced sensing devices

This manuscript presents a comprehensive investigation into the optical properties and topological edge states (ESs) of one-dimensional plasma photonic crystals composed of alternating plasma and dielectric layers. We use the transfer matrix method and numerical simulations to study how incident angle, plasma frequency, and collision frequency influence topological ESs. These modes form at the interface between two plasma photonic crystals with differing Zak phases. Our results reveal that topological ESs, characterized by strong localization and robustness against structural imperfections, emerge within overlapping photonic band gaps when topological invariants differ. A key innovation of this work is the realization of high-Q topological ESs with minimal structural complexity: a Q-factor as high as 7160 is achieved with just three periods, representing a significant advancement over traditional multilayer designs. We demonstrate that while the topological ES peak frequency is independent of the number of periods, its Q-factor and spectral characteristics can be dynamically tuned by adjusting structural and material parameters. Notably, topological ES peak frequencies are tunable from 20 to 28 GHz through variations in incident angle (0° to 80°) and plasma frequency (30–60 GHz), achieving peak transmissions up to 0.98 at 22.91 GHz. These findings establish a new paradigm for topologically protected, compact, and dynamically tunable photonic devices, with promising applications in integrated photonic circuits, optical filtering, and high-precision sensing.