Research On High Speed Single-photon Detection Mutual-differencing Technology And Ultra-low Light Imaging

Single-photon detection is a technology that is used to detect ultra-low light signals, by which even a single photon can be detected. A single photon is commonly supposed to be the weakest energy that can be detected. With the rapid development of quantum cryptography, laser radar 3D imaging, ultra-low light imaging and non-line-of-sight communication, a single-photon detector with higher counting rate is needed. In the thesis, mutual-differencing is applied to research how to improve the counting rate of a single-photon detector. Single-photon detectors'application in the ultra-low light 2D imaging is investigated and researched.The advantages of mutual-differencing method are illustrated in the thesis. In a mutual-differencing mode, the single photon detector's sampling frequency can be improved and adjusted without changing the hardware. Based on the differences of the foreign APD and the domestic APD, experiments are setup to verify the advantages. The foreign APD (PGA400 SPAD from Princeton Lightware) is able to detect a single photon. Matched with an ordinary diode, PGA400 is used to detect single photons under 100MHz sampling frequency. However, it's hard to get avalanche signals with high SNR due to the phase difference and signals'mismatching. Therefore, PGA400 can't work well in high speed single photon detection. The domestic APD is matched with the other APD, which is made with the same material and technology, resulting in excellent signals with high SNR even under the sampling frequency higher than 500MHz. Besides, experiment platforms are designed to investigate working mode, frequency response, sensitivity and photoelectric gain. The results are analyzed and it is expected to illuminate a way for the domestic APD to be used in high speed single-photon detection.Single-photon detectors can be used in many fields due to its significant potential. A typical application in the ultra-low light 2D imaging is investigated in the thesis. Based on compressive sensing, a new scheme of photon-counting imaging system is proposed. It takes a single-photon counter as the detector, hoping to use this kind of point-type detector to detect ultralow light while the plane-type detector is not very developed. By performing simulation on the computer, the feasibility of the system was verified. Compared to IWT algorithm, SpaRSA-DWT algorithm was proposed and applied for image reconstruction.