Selective Light Absorption and Spectral Manipulation via an Electro-Optical Nano-Cavity

A frequency-region selective light absorber is theoretically investigated by an electro-optical waveguide cavity coupled plasmonic micro-structure. A spectrally separated broadband near-unity absorption in the visible and the narrow band absorption peak in the near-infrared regime are simultaneously achieved due to the different resonant behaviors located in the different positions of the stereostructure. This spatial and frequency selective light absorption shows impressive distinct behaviors during the electro-optical (EO) operation. The absorption band in the visible maintains well while the absorption peak in the longer wavelength range presents a sensitive response to the external voltage. Based on the numerical simulation, a spectral shift related sensitivity reaches 7.1 nm/V for the infrared absorption peak when the applied voltage is launched. Meanwhile, the absorption efficiency is still keeping in the high level with the intensity exceeding 97.5%. These findings open a facile way for differential light absorption and spectral manipulation via the well-design of spatial geometry-related resonant metamaterial.