Tunable Fano Resonance for Optimized Performance in High-Efficiency Photonic Filters

A basic photonic device is engineered using two resonators attached either at two distinct points (forming a U-shaped structure) or at the same location (creating a crossed structure) along a waveguide. This configuration is designed to generate Fano and electromagnetically induced transparency (EIT) resonances within the transmission spectrum. These resonances arise due to internal interactions within the structure: Fano resonances occur when the resonance is near a transmission zero, while EIT resonances manifest when positioned between two transmission zeros. As an application, Fano resonances, characterized by their asymmetric profile, allow for the design of highly selective optical filters. These filters are capable of distinguishing between wavelengths that are very close together, which is crucial for telecommunication systems and integrated photonic circuits.