Fano Resonance in Artificial Photonic Molecules

The spectral signatures of chemical molecules are dependent on the hybridization of electronic states. The artificial photonic molecules formed by structured optical microcavities, exhibiting Fano features with sharp asymmetric line shape and strong field enhancement, hold various potential applications in sensors, optical switches, lasing spasers, optical diodes, etc. To design high-performance photonic devices, it is of great importance to gain the formation and modulation mechanisms of Fano resonance in various artificial photonic molecules. This review is focused on the Fano resonance in artificial photonic molecules. It starts by discussing the properties of Fano resonance, followed by a detailed discussion of the coupled oscillator model and coupled mode theory that could reveal the underlying mechanisms. Then, different types of photonic molecules for realizing Fano resonance are presented, and several representative exciting applications are introduced. Finally, a summary and a brief outlook on challenges are discussed for Fano resonance in artificial photonic molecules.