Narrow Trench Plasmonic Mid-Infrared Detector with Distinct Responsivity for Reconstructive Spectroscopy

Reconstructive spectroscopy in the mid-infrared (MIR) range is a prospective technology making the rich information in the MIR range more accessible, while distinct wavelength-responsivity characteristics are required. We report a room-temperature operating plasmonic MIR detector that shows sharply wavelength-dependent responsivity by itself, spanning a wide magnitude range. A grating with narrow, continuously aluminum-covered trenches not only showed a sharp responsivity peak with a half-width half-maximum of 43–57 nm but also suppressed the minimum responsivity to below 20% of the maximum. With a clear grating parameter-responsivity relationship observed, the structure will commit to improving the miniaturized MIR reconstructive spectroscopy.