Gaige Zheng

Tunable Spectrum Selective Enhanced Absorption of Monolayer Graphene in Fano Resonant Waveguide Grating with four-Part Period

Spectral responses of a novel resonant waveguide grating (WGG) configuration, in which monolayer graphene is prepared on top of the WGG, and the period is composed of two grating ridges with identical width are presented. Fano-like resonance can effectively improve the graphene absorption from 2.3 to 63.2xa0%. And the absorption width can be tailored without modifying the spectral lineshapes and sideband levels, while the maximum absorption wavelength linearly varies with the increase of period. The situation of oblique incidence is studied as well. Fano-like resonant grating suggests a new opportunity for the design of tunable graphene photonic and optoelectronic devices.

Tunable Fano Resonances in Mid-Infrared Waveguide-Coupled Otto Configuration

A planar silicon carbide/dielectric multilayer structure is investigated in Otto geometry, where surface phonon polaritons and planar waveguide mode can be coupled to realize Fano resonances under transverse magnetic polarization. The resonance coupling is analytically demonstrated using the coupled harmonic oscillator model and numerically presented through rigorous coupled-wave analysis calculations, which shows that the coupling strength between different resonances and the resonant wavelength matching condition plays an important role in the bandwidth and position of the Fano resonance (FR); the magnetic field distribution was also shown to explain the origin of FRs qualitatively.