Single-detector MIR microspectrometer based on a MEMS microshutter array

We report a method of spectrum reconstruction in mid-infrared (MIR) range with a single photodetector (PD), enabled by a pre-patterned MIR filter whose transmittance spectrum is modulated by a micromechanical system (MEMS) microshutter array (MSA). By changing the opening states of the MSA pixels, a variety of transmission spectra can be generated from the same filter. A single-pixel PD is used to record the optical power transmitted through the MIR filter for each MSA configuration. A deep neural network (DNN) is introduced to decode the MSA-modulated optical powers to reconstruct the full spectrum of a light under test. The employed MSA has 4 × 8 pixels with each pixel's opening of 2.5 × 1 mm. By applying 10 different MSA configurations, a full spectrum of a light source with a spectral range from 3 to 5 μm has been successfully reconstructed. The mean squared error between the reconstructed spectrum and ground truth is less than 1%. Compared to those systems that rely on expensive MIR photodetector arrays, this proposed method provides a low-cost solution for MIR spectrometers.