Advancements and Future Prospects in Mid-Infrared Detection Technology Using Optical Frequency Up-Conversion

The mid- infrared band holds important application value in frontier fields such as environmental remote sensing, astronomical observation, biomedical diagnosis, and molecular spectroscopy. High-performance mid- infrared detection technology is crucial for realizing these applications. Advances in narrow-bandgap semiconductors and heat- sensitive material technologies have greatly improved the performance of mid- infrared detectors. Despite this progress, mid- infrared detectors still lag behind InGaAs/Si-based detectors functioning in adjacent bands, particularly in avalanche/ counting and planar array configurations. The frequency up- conversion of mid- infrared light using mature near- infrared and visible light devices to achieve high-level analysis and sensing has emerged as a new indirect detection paradigm that effectively complements traditional direct detection methods. This paper reviews the development history of mid- infrared frequency up- conversion detection technology both domestically and internationally, classifies the "four elements" of a detection system (i. e. , a nonlinear crystal, a probe light source, a mid- infrared target, and an optical detection terminal), and summarizes the key advances in mid- infrared single photon detection, spectral analysis, and imaging applications. The paper also discusses future directions for advancements in detection technology.