Subwavelength plasmonic absorbers for spectrally selective resonant infrared detectors

This work presents the first resonant infrared (IR) detectors with integrated nanostructured subwavelength plasmonic gratings designed to selectively absorb long wavelength infrared (LWIR) radiation. The resonant detectors are the smallest in size demonstrated so far. The absorbers are optimized for a spectral wavelength of 10.15 μm and experimentally demonstrate an absorbance of 46% with a Full Width at Half Maximum (FWHM) of 1.7 μm. The absorbed thermal energy causes a fast (sub-millisecond) proportional change in the frequency of the resonator. The combination of resonant IR detectors with integrated plasmonic absorbers enables spectrally selective IR detectors. Each detector in the array can be optimized for different wavelengths, thus enabling a multi-spectral array for IR spectroscopy and multispectral thermal imaging. Keywords—micromechanical resonator, IR detector, plasmonics, metamaterial.