Dynamic reversal of Fano response of metagratings by rotation of linear polarization

Le résumé fourni par la source

Fano resonance features asymmetric spectral line shape and holds numerous potential applications such as filters, sensors, lasers, nonlinear optics, and slow-light devices. However, general methods to achieve Fano resonance face substantial challenges because of their limited dynamic parametric tunability. Here, we present a theoretical demonstration of an alternate method to realize dynamically reversing the magnitude and line shape of the Fano profile in anisotropic bilayer metallic gratings by simply manipulating the polarization angle of incident light. By introducing an in-plane shift in one grating layer, the resonant phase of the hybridized plasmon modes formed within the bilayer system transforms between in phase and out of phase with the polarization direction, leading to the asymmetry reversal of the Fano line shape. This concept can be demonstrated and explained by applying a deduced temporal coupled-mode theory, which reveals that the asymmetry parameter $q$ undergoes a sign reversal along with the reversal of Fano line shape. This theory is further examined with the results of numerical simulations, finding excellent agreement between them. Our proposed approach enables completely and dynamically reversing the spectral asymmetry of the Fano resonance in an anisotropic bilayer grating, showing potential for applications involving active control and manipulation of Fano resonance.

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