Realisation of ultra-sensitive detection in the mid- and far-infrared wavelengths has always been an international research hotspot, not only promoting the development of infrared precision spectroscopy, infrared ultrafast photonics and infrared space astronomy and many other basic research, but also in the field of free-space communications, missile imaging and tracking and positioning, infrared early warning, infrared remote sensing, long-range explosives detection and other major military ** field has an important application, and it is also widely used in meteorological monitoring, air pollution monitoring, material processing, disease detection and other aspects of civil industry.
Recently, Professor Zeng Heping's team has completed the construction of the mid-infrared single-photon detector based on nonlinear frequency conversion, which uses the nonlinear and frequency process to coherently convert the infrared light field to the visible wavelength band, combined with the time-frequency domain precision control of the synchronous pulse pumping technology, to achieve the improvement of the nonlinear conversion efficiency and parametric fluorescence noise suppression, and ultimately obtained a high conversion efficiency of 80%. Thanks to the highly efficient filtering system, the overall detection efficiency in the 3-micron band reaches 37%, and the noise equivalent power is 1.8×10-17 W/Hz1/2, which is one of the detectors with the highest sensitivity under room temperature operating conditions in the world.
In addition, the team demonstrated for the first time the mid-infrared photon-number-resolvable detection capability by combining the frequency upconversion technique and the multi-pixel photon-counting array, achieving the precise identification of up to nine photons under ultra-low noise. This technology will provide a powerful tool for the development of high-performance photon detection and counting in the mid-infrared, and is expected to be applied to frontier applications such as long-distance space communication, remote spectral analysis, and air-ground laser mapping.
The work was supported by the collaboration of Associate Professor Yan Liang and Associate Professor Qiang Hao at Shanghai Institute of Technology and published in Photon. Res. 9, 259-265 (2021).
