Mid-infrared photon counting and resolving via efficient frequency upconversion

• Published in: Photonics research (Washington, DC) DC), 2021-02, Vol.9 (2), p.259
• Main Authors: Huang, Kun, Wang, Yinqi, Fang, Jianan, Kang, Weiyan, Sun, Ying, Liang, Yan, Hao, Qiang, Yan, Ming, Zeng, Heping
• Format: Article
• Language: English
• ISSN: 2327-9125; 2327-9125
• DOI: 10.1364/PRJ.410302

Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications. Specifically, the capability of extending operation wavelengths into the mid-infrared region is highly attractive. Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3 μm. Thanks to the spectrotemporal engineering of the involved optical fields, the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%. In combination with a silicon avalanche photodiode, we obtained unprecedented performance with a high overall detection efficiency of 37% and a low noise equivalent power of 1.8 × 10 − 17    W / Hz 1 / 2 . Furthermore, photon-number-resolving detection at mid-infrared wavelengths was demonstrated, for the first time to our knowledge, with a multipixel photon counter. The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14% at the peak detection efficiency. The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy, sensitive biochemical sensing, and free-space communications, among others.