Single-Pixel Shortwave Infrared Imaging Based on PbS Quantum Dots

Shortwave infrared (SWIR) imaging technology, with its excellent penetration and anti-interference capabilities, is widely applied in military, medical, and industrial fields. However, traditional detectors (e.g., InGaAs) are expensive, have complex readout circuits, and exhibit insufficient low-light performance, limiting their large-scale promotion. This paper proposes and implements a single-pixel SWIR imaging system based on PbS quantum dot (QD) detectors. A single-pixel imaging system is constructed using PbS QD detectors with a formal device structure (ITO/ZnO/PbS/PbS-EDT/Au); through simulation studies, the effect of the PbS absorption layer thickness on device performance is investigated, and it is determined that a thickness of 450 nm yields optimal device performance. Based on the simulation results, a P-I-N structure PbS photovoltaic-type detector with high external quantum efficiency (EQE) and low dark current is fabricated, achieving a EQE of 62% at the 1300 nm wavelength, a dark current density of 8.54 × 10^-4 mA·cm^-2 at -0.1 V bias voltage, and a -3 dB bandwidth of 324 kHz; a low-noise signal conditioning circuit is designed to optimize the -3 dB bandwidth to 337 kHz while maintaining low noise density, enabling the linear conversion of nA~μA level weak photocurrent from the detector to 0~3 V standardized voltage signals, meeting the requirements of single-pixel imaging (SPI) systems. Hadamard orthogonal encoding technology is employed to achieve spatial light modulation and signal encoding; after the PbS QD detector collects and integrates the projection signal, the image with 128 × 128 resolution is reconstructed through the inverse Hadamard orthogonal decoding algorithm. This work provides a novel solution for QD-based SWIR imaging, overcoming the cost and manufacturing limitations of traditional array systems and laying the foundation for the spectral expansion and practical application of SPI technology. Quantitative imaging characterization and low-light imaging tests are supplemented to verify the comprehensive performance of the system.