Recently, the review paper "Advances in near-infrared avalanche diode single-photon detectors" by Shi Yanli's team of Yunnan University was published in the global cutting-edge comprehensive research journal Chip. This review paper presents the development of near-infrared single-photon detectors.
In recent years, single-photon detection technology has shown broad application prospects in many fields such as quantum secure communication, quantum computing, artificial intelligence, and military detection, making single-photon detectors a current research hotspot.
Photons are absorbed to produce hole-electron pairs, and holes enter the multiplication region unde the electric field to trigger avalanche multiplication.
Semiconductor avalanche diode detectors have internal avalanche gain, fast response, small size, low cost, and easy integration. They can achieve a working temperature of about minus 40 °C through semiconductor refrigeration, making them a better choice for single-photon detectors. Among them, the InP/InGaAs near-infrared single-photon detector is the most mature near-infrared avalanche diode single-photon detector at present. Its single-tube and array have been commercialized products. The main performance indicators include: single-photon detection at minus 40 ℃ The efficiency exceeds 30%, the dark count rate is less than 10kHz, the post-pulse probability is less than 5%, the time jitter is less than 100ps, and the maximum count rate exceeds 100MHz. The center distance of the focal plane array is 50um, and the array size is 256×128. Two imaging methods, photon counting and photon timing, can be used for three-dimensional imaging. At present, single-photon focal plane arrays with smaller center distance (25 microns) and larger specifications (320×256 size or above) are being developed at home and abroad. The emergence and new progress of InP/InGaAs near-infrared single-photon detector products provide the possibility for the large-scale application of such detectors.
Development direction of single photon detectors
At present, the development of single-photon detectors is mainly advancing rapidly along two paths: one path is to continuously optimize the performance of existing InP/InGaAs SPADs, towards smaller dark counts, lower after-pulses, higher count rates and more High working temperature and other directions. The challenge is that material defects in the multiplication layer lead to large post-pulse effects, long dead times (time without avalanches), and reduced count rates. The current technical means have certain mutual constraints: in order to reduce the post-pulse, by reducing the amount of avalanche charge, which leads to the problem of low detection efficiency; by prolonging the dead time, it leads to the problem of low count rate; by increasing the temperature, the trapping is reduced. The lifetime of the carriers leads to the problem of high dark count rate. The existing solution is to use the development of integrated quenching circuits to minimize parasitic capacitance and post-pulse, and at the same time, to further improve the growth quality of multiplication layer materials.
The performance optimization and application of single photon detectors are inseparable from the support of quenching circuits. On the one hand, the quenching circuit needs to stop the avalanche in time, and on the other hand, it also needs to suppress the noise from the device and circuit, etc., to bring out the avalanche signal in advance. At present, through the integration of quenching resistance or potential barrier of the device itself, through the monolithic integration of external quenching circuits, and through the combination of sinusoidal gating and different quenching circuits, the dark count and post-pulse of the device are significantly reduced, and the device is improved. count rate.
Working principle of SPAD-based single-photon detectors.
Another way is to find more promising new materials and new mechanism devices. Stimulated by huge application demands, new materials such as low-noise material development based on low k-factor, wavelength extension based on low-dimensional materials, noise reduction based on ionization multiplication engineering, and high gain multiplication based on ballistic transport of low-dimensional materials, Devices with new mechanisms have emerged, and the development of these new technologies has opened up new directions for further reducing the noise of single-photon detectors, improving signal-to-noise ratios, extending wavelengths, and improving device working conditions.
Important application areas of near-infrared single-photon detectors
Near-infrared single-photon detectors have the ultimate sensitivity of photon detection, and their working bands are the main bands used by traditional optical fibers, and are also eye-safe bands. Driving, 3D imaging, weak signal detection and other fields have important applications.
When the laser radar uses a 1550nm laser as the emission light source, due to the safety of the human eye, a higher power laser can be used, so that it can detect a longer distance, so that the current detection distance is from 100m to 200m, and the light with a wavelength of 1550nm is The natural light environment has cleaner background noise, which is of great significance for the application of unmanned or vehicle-mounted lidar. It is expected that the development of 1550nm single-photon detectors will significantly promote the rapid development of unmanned and lidar technologies.
This paper introduces the development of single-photon detector technology and related new technologies based on InP/InGaAs, aiming to help increase the understanding and understanding of near-infrared single-photon detectors, expand their applications, and provide further performance improvement and development. refer to.
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