In this study,to achieve high-speed,high-sensitivity,and low-cost laser communication,we optimized and improved a new InGaAs/InP single-photon avalanche diode(SPAD)to better apply to the near-infrared laser communication system detected using a single single-photon detector(SPD).Compared with the previous generation,we added a dielectric-metal reflective layer and improved the double Zn diffusion process while optimizing the structure of each layer.The fabricated InGaAs/InP SPAD achieved a photon detection efficiency(PDE)of 30%,a dark count rate(DCR)of 3 kHz,and an afterpulsing probability(Pap)of 2.4%under a high-frequency sine-wave gate(SWG)operating mode with a frequency of 1.25 GHz,temperature of 225 K,and bias of 6 V.A free-running negative feedback avalanche diode(NFAD)prepared based on the high-performance SPAD was used as a receiver in the real-time spatial laser communication system.The performance parameters of the laser communication system with the NFAD were experimentally obtained.The experimental results show that the InGaAs/InP NFAD with a bit rate of 1 Mbit/s using the 4-pulse position modulation(4PPM)scheme has a bit error rate of 1.1×10-5 and sensitivity of-69.6 dBm.
InGaAs/InPsingle-photon detectorsingle-photon avalanche diodenegative-feedback avalanche diodephoton detection efficiencylaser communication
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