关键词: 激光通信/
光电探测/
超导纳米线单光子探测器/
误码率
English Abstract
Model of bit error rate for laser communication based on superconducting nanowire single photon detector
Yan Xia-Chao1,Zhu Jiang1,
Zhang La-Bao1,
Xing Qiang-Lin2,
Chen Ya-Jun1,
Zhu Hong-Quan2,
Li Jian-Ting2,
Kang Lin1,
Chen Jian1,
Wu Pei-Heng1
1.Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093, China;
2.Beijing Institute of Tracking and Telecommunications Technology, Beijing 100094, China}
Fund Project:Project supported by the National Basic Research Program of China (Grant No.2017YFA0304002) and the National Natural Science Foundation of China (Grant Nos.11227904, 61471189).Received Date:09 May 2017
Accepted Date:05 June 2017
Published Online:05 October 2017
Abstract:The high-speed deep space communication is one of the key technologies for deep space exploration. Laser communication system equipped with sensitivity of single photon will improve existing deep space communication speed. However, laser communication at single photon level needs to consider not only the effect of transmission environment, but also the performance of used single photon detector and the photon number distribution. As a new single photon detector, superconducting nanowire single photon detector (SNSPD) outperforms the traditional semiconducting SPDs at near infrared wavelengths, and has high detection efficiency, low dark count rate, low timing jitter, high counting rate, etc. The SNSPD can be used for detecting single photons efficiently, rapidly and accurately. In this paper, we introduce the system detection efficiency and dark count rate of SNSPD based on the photoelectric detecting model without considering the effect of atmospheric turbulence, establish the mathematical model of bit error, and put forward the formula of system bit error rate. What should be emphasized is that the bit error rate is an important parameter for measuring the performance of laser communication system. Error is partly from background thermal radiation and circuit electromagnetic interference; in addition, error appears when photons reach the surface of device without being absorbed to successfully produce resistance area or photons are absorbed but there occurs no response. As a result, the calculation of bit error rate includes the whole process of photoelectric conversion. In order to analyze how to affect the size of system bit error rate, first we simulate two factors of the formula, i.e., light intensity and laser pulse repetition frequency. The results show that the light intensity has the greatest influence on error bit rate. With the light intensity increasing from 0.01 to 1000 photon/pulse, the error bit rate significantly decreases from 10-1 to 10-7 level. The influence of laser pulse repetition frequency is restricted by the light intensity, which declines with the increase of pulse repetition frequency. Then we measure the error bit rate experimentally, which validates the simulation model. However, when increasing light intensity or speed, experimental bit error rate is about 10-4 times higher than simulation result. The reason may be that the insufficiency of actual communication modulation extinction ratio of optical signal to the background noise through optical fiber increases the dark count rate. The above model and experimental results could be the foundation of high-speed deep space laser communication such as moon-earth and Mars-earth based on SNSPD.
Keywords: laser communication/
photoelectric detection/
superconducting nanowire single photon detector/
bit error rate
