Phase‐Coupling‐Induced Far‐Field Modulation between Nontrivial and Trivial Modes in Cavity–Waveguide Systems

Abstract

Photonic crystal (PhC) can be accurately designed to generate nontrivial and trivial modes, that is, edge states (ES)/corner states (CS) and cavity modes, respectively. The coupled cavity–waveguide system designed by PhC provides a chip‐scale platform to manipulate electromagnetic (EM) waves that is usually based on near‐field coupling between nontrivial and trivial modes. However, the far‐field interaction between nontrivial and trivial modes for manipulating EM waves has not attracted wide attention yet. Herein this article, the coupled cavity–waveguide systems, which consist of two separated CS cavities (interacting with single/multiple trivial cavity/cavities) coupled by means of an ES waveguide, are designed to robustly tune the transmission properties of EM waves by modulating the phase coupling between CS cavities. As proof‐of‐principle examples, single‐, dual‐, and triple‐electromagnetically‐induced‐transparency‐like (EIT‐like) phenomena with tunable transmission spectra are theoretically and numerically demonstrated by controlling the distance (generated phase accumulation) between the CS cavities. In addition, the robustness in generating EIT‐like transmission characteristics is also demonstrated due to the robustness of the CS cavities. The unique cavity–waveguide systems with unprecedented capability in robustly tuning the transmission spectra of EM waves can be extended to design other high‐performance devices with potential applications in sensing, detecting, and information processing.