Study On High-speed Single-photon Detection And Applications

The past decades have seen a dramatic increase of interest in various kinds of new single-photon detectors (SPDs) technologies and their wide application, including quantum optics and classi optics. These detectors have served as indispensable key devices in both basic and application physics research. Although different SPDs have their own advantages and disadvantages, the SPDs based on Avalanche Photo-Diode (APD) are one of the most important detectors. Among all kinds of detectors, APD based SPDs have some special advantages, such as high detection efficiency, large dynamic range, relatively low bias voltage, low power consumption；and relatively simple system-structure. Thus, they have been widely used in quantum optics, quantum information, ultra-sensitive spectroscopy, bio-photonics and medical-photonics. However, there are still lots of potential technical breakthrough and new application waiting for us to discover. My works in this thesis mainly focus on the development and new application of high speed APD-based single-photon detectors and photon-number-resolving detectors. Besides, I theoretically and experimentally verified the applications of SPD in quantum-key-distribution, quantum-random-number-generator, laser ranging and3D imaging system. And I am trying to expand the application possibilities of APD-based photon-counting detectors in quantum optics and lidar system.The works demonstrated in this thesis include:1. A deeper study on GHz sine-wave gated InGaAs/InP APD indicated that it can be operated in a quasi-continuous mode. The research also showed that the APD, operating in the sine-wave gating mode, combined both advantages of gate mode and countinue mode. We tested its timing performance and found out the key influencing factor. The optimized1-GHz sine-wave gated InGaAs/InP SPD could offer4.7%detection efficiency and180-ps timing jitter.2. We demonstrated a single-photon laser ranging system at1550nm with an optimized1-GHz sine-wave gated InGaAs/InP APD SPD. By using a time-of-flight TCSPC approach, we achieved3cm depth resolution at32m distance in daylight environment. It provides a simple way to build an ultra-high sensitive1550nm laser ranging system at eye-safe spectral region. Benefiting from low power consumption of the devices used in this system, it is promising to be a mobile single-photon range finder for long-distance application.3. We demonstrated a laser ranging experiment obtained with a Geiger-mode silicon avalanche photodiode (Si GAPD). The surface-to-surface resolution of15cm was achieved with TCSPC. In the experiment, a mode-locked Yb-doped fiber laser at1036nm was applied, which made the detection efficiency of Si APD increased from4.3%to9.7%, comparing with1064-nm laser-source ranging system. And the system could measure the non-cooperated object longer than14.3km far away with1μJ per pulse laser output theoretically, which was tested through inserting the optical loss. It presented a potential for hundreds-of-kilometer laser ranging at low-light level.4. We demonstrated a3D laser imaging system at1550nm with an optimized1.5-GHz sine-wave gated Geiger-mode InGaAs/InP APD single-photon detector. Two computer-controlled galvanometer mirrors steered the laser beam over the target and scanned in a pixel-by-pixel raster-scanning pattern. Meanwhile the time-of-flight measurement on the arriving photons provided the distance information of the targets, thereby achieving3D laser imaging. This system has shown a potential of low-energy and eye-safe fast3D laser imaging system for long-distance measurement. 5. We demonstrated a high-efficiency quantum random number generator which takes inherent advantage of the photon number distribution randomness of a coherent light source. This scheme was realized by comparing the photon flux of consecutive pulses with a photon number resolving detector. The random bit generation rate could reach2.4MHz with a system clock of6.0MHz, corresponding to random bit generation efficiency as high as40%.6. For the first time to our knowledge, we realized the counterfactual QKD experiment in a round-way unbalanced Mach-Zehnder interferometer of12.5km fiber length. The counterfactual QKD protocol provides a powerful security proving method by monitoring the photon distribution of each detector. Despite7.2%of error rate on Bob’s data, the security of the system is guaranteed that there is no intercept-resend attack according to the unchanged photon distribution of each detector used in the QKD system. And secret keys could be obtained preventing the passive PNS attack. The counterfactual QKD scheme was implemented with currently available technologies, promising a robust and practical quantum cryptography system toward global secure communication.