Cavity-enhanced infrared quantum dot homojunction arrays

Infrared spectroscopy has wide applications in the medical field, industry, agriculture, and other areas. Although the traditional infrared spectrometers are well developed, they face the challenge of miniaturization and cost reduction. Advances in nanomaterials and nanotechnology offer new methods for miniaturizing spectrometers. However, most research on nanomaterial-based spectrometers is limited to the visible wavelength or near infrared region. Here, we propose an infrared spectrometer based on diffraction gratings and colloidal quantum dot (CQD) homojunction photodetector arrays. Coupled with a Fabry-Perot cavity, the CQD photodetector covers the 1.4–2.5 μm spectral range, with specific detectivity 4.64 × 10¹¹ Jones at 2.5 μm at room temperature. The assembled spectrometer has 256 channels, with total area 2.8 mm × 40 mm. By optimizing the response matrix from machine learning algorithms, the CQD spectrometer shows high-resolution spectral reconstruction with a resolution of approximately 7 nm covering the short-wave infrared.