Solid-state micro-spectrometer based on a linear array of infrared resonant-cavity-enhanced photodetectors

Abstract

We demonstrate a novel solid-state spectrometer employing a linear array of resonant cavity enhanced photodiodes (RCE-PDs) with a spatial chirp. By epitaxially grading the thicknesses of the distributed Bragg reflector mirrors, the chirp can cover a total bandwidth of ≥0.1 × λ res where λ res is the resonant wavelength. This new class of sensor is intended for analyzing IR absorption fingerprints and our group has already demonstrated conventional RCE-PDs between 2.2 -7.8 µm. In theory the range between 1.55 and ~12 µm could be served using the same materials. This region covers important spectral fingerprints including chemical and pollutant gases, as well as threat agents including thiodiglycol and VX.