基于InGaAs NFAD的集成型低噪声近红外单光子探测器

近年来，单光子探测技术在激光雷达等方面的应用越来越受到研究人员的关注。研制了基于InGaAs负反馈雪崩二极管(Negative Feedback Avalanche Diode, NFAD)的自由运转式集成型近红外单光子探测器。设计将被动淬灭原理的NFAD与主动淬灭技术结合，针对NFAD的信号读出电路易受电磁干扰的问题，创新地提出了无前级放大器的雪崩信号高阻抗差分提取电路，并采用吸波材料对关键电路部分进行了屏蔽，同时提高了淬灭性能和稳定性。此外，为了降低暗噪声计数率，针对集成制冷型NFAD器件的散热进行了详细的热设计，对集成热电制冷的NFAD器件和高速淬灭电路发热量较大的特点进行了电路和散热结构设计优化。通过实验对淬灭电路性能、散热设计和抗干扰设计进行了验证。结果表明：无前置放大器设计的探测器性能稳定，对1 550 nm波长光子的最高探测效率可达33%，在-50℃、10%探测效率时可用死时间低至120 ns，此时暗计数率890 Hz，后脉冲概率10.6%。探测器散热性能良好，环境20℃风冷下的最低制冷温度可稳定在-58℃。上述结果表明这一低噪声计数、高集成度的通信波段近红外单光子探测器...

Integrated low-noise near-infrared single-photon detector based on InGaAs NFAD (invited)

  Objective  Single-photon detection technology has attracted attention of researchers increasingly in recent years. The development of negative feedback avalanche diode (NFAD) which integrates a quenching resistor for fast quenching has greatly lessened the afterpulsing effects in InGaAs/InP based near-infrared single-photon detectors. Moreover, the integration of the thermal-electric cooler (TEC) with the NFAD has made the detector small in size and low in power consumption. However, the integration of the quenching resistor with large resistance reduces the amplitude of the avalanche current output to tens of μA. Though it can be read out using a broadband pre-amplifier, the long bonding wire of the TEC-integrated NFAD makes it prone to electro-magnetic interference. In addition, the large parasitic inductance and capacitance of the long bonding wire, combined with the low amplitude of the avalanche signal, makes it hard to cancel the noise induced by the capacitive response of the recovery signal of the NFAD, and hence it is difficult to use active-quenching circuits for better performance. Therefore, it is required to design a sophisticated circuit to solve the problems above to facilitate the application of the NFAD-based single-photon detector.   Methods  An integrated free-running InGaAs near-infrared single-photon detector was developed based on negative feedback avalanche diode (NFAD). In order to tackle with the problem that the readout of the avalanche current is prone to interference when using an amplifier, a high-impedance differential circuit without pre-amplifier was proposed for avalanche signal extraction. By introducing a specially designed resistive-capacitive network and signaling, the active-quenching technique was successfully combined with NFAD and was able to work stably. In addition, shielding material was applied to the amplifier-free readout circuitry for further interference shielding. The design above enhanced the quenching performance and stability of the detector at the same time. Moreover, in order to lower the dark-count rate, the circuit and the heat-dissipation structure of the detector was optimized to maximize the thermal contact area, and hence the high heat from the integrated thermal-electric cooler of the NFAD and the high-speed quenching circuit can be quickly dissipated to achieve lower cooling temperature.   Results and Discussions   The performance of the quenching circuit, the thermal design, and the anti-interference were verified through experiments. Waveforms at the inputs of the comparator (in Fig. 3) showed that the performance of the detector without pre-amplifier was stable. The maximum detection efficiency for 1550 nm wavelength reached 33%, and the minimum dead time available was 120 ns at the detection efficiency of 10%, at ?50 ℃, where the dark-count rate and afterpulse probability were as low as 890 Hz and 10.6%, respectively. The heat-dissipation performance was good enough to maintain the temperature of the NFAD at ?58 ℃ with fan cooling when the ambient temperature was 20 ℃. At ?30 ℃, the afterpulse probability was approximately 70% of the value at ?58 ℃, at the cost of a higher dark count rate of 13.2 times of the value at ?58 ℃.   Conclusions  The proposed amplifier-free avalanche extraction and active-quenching circuit was able to work with the NFAD stably with a threshold of 9 mV, showing an excellent anti-interference performance. The afterpulse probability was as low as 10.6% at 10% detection efficiency, 120 ns dead time, ?50 ℃, indicating that the hybrid quenching performance of the active-quenching circuit with NFAD was sufficient for low-dead-time free-running operation of the detector. In addition, good heat-dissipation performance was achieved by the large-thermal-contact-area design, where the temperature of the NFAD reached ?58 ℃ with fan cooling at an ambient temperature of 20 ℃. It is indicated that this highly integrated low-noise near-infrared single-photon detector for communication wavelengths is especially suitable for use in the applications where high performance and minimum space usage are required.