High sensitivity optical communication based on single-photon detection polarized pulse position modulation

We demonstrate a high sensitivity optical communication system with 4 superconducting nanowire single photon detectors. A coding method is invented based on the polarized pulse position modulation (PPM), which increases the capability of suppressing the background and increases the information of each photon pulse by 50%. A mathematical model is established to analyze the theoretical performance of the PPM and hybrid modulation system. The results show that the hybrid modulation system has higher sensitivity in high background noise. The performance of the polarized PPM optical communication system is verified under the background noise of intensity from 0.8 x 10(6) counts per second to 8 x 10(6) counts per second, and the experimental results are in good agreement with the theoretical predictions. The polarized PPM system offers an enhanced solution for the long distance free-space optical communication under high intensity of background noise, and the performance research provides a new method for optical vortex beams to achieve all-day real-time communication based on single-photon detection.