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 $1.8\times {10}^{-17}\mathrm{W}/{\mathrm{Hz}}^{1/2}$. 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.

中文翻译：

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通过有效的频率上变频进行中红外光子计数和解析

具有单光子灵敏度和大动态范围的光学探测器将促进多种应用。具体地说，将工作波长扩展到中红外区域的能力非常吸引人。在这里，我们实现了一个中红外频率上转换检测器，用于计数和分辨3μm的光子。由于所涉及的光场的光谱时间工程性，中红外光子可以以80％的转换效率光谱转换为可见带。结合硅雪崩光电二极管，我们获得了空前的性能，整体检测效率高达37％，噪声等效功率低$1.8\times {10}^{-17}\mathrm{w\; ^}/{\mathrm{赫兹}}^{\mathrm{1个}/2}$。此外，据我们所知，首次使用多像素光子计数器演示了中红外波长下的光子数解析检测。实施的上转换检测器在峰值检测效率下，最大分辨光子数达到9，每个脉冲的噪声概率为0.14％。所获得的光子计数和分辨性能可能会为痕量分子光谱学，灵敏的生化传感以及自由空间通信等领域开辟新的可能性。