Research On Optical Communication Technology Based On Single-photon Detection

Free-space optical(FSO)communication is widely used in satellite,inter-satellite and deep space communication,high precision satellite-to-ground time service and space gravitational wave detection for the advantages of high data rate,wide bandwidth,low power,small mass and unlicensed spectrum.Long-distance FSO communication exists huge link loss,and the requirement for the data transmission efficiency is greatly improved with the explosive growth of information.Optical communication based on single-photon detection can solve the problem of sensitivity,and has made important progress in Earth-Moon communication and all-optical satellite relay communication system.However,the single-photon detector has the problems of probability detection,dead time and noise counting,which makes the optical communication system has low data rate and high bit error rate(BER).In view of the above problems,the FSO communication technology based on single-photon detection is studied.Multi-channel single-photon detection is used to improve the sensitivity and anti-noise performance of optical communication,multi-dimensional coding method is proposed to improve the channel capacity,and an integrated system of time comparison,optical ranging and communication is invented to meet the requirements of space gravitational wave detection.The details are summarized as follows:1.A polarized pulse position modulation(PPM)coding method based on single-photon detection is developed.A pair of orthogonal polarized light is combined with 4-PPM to expand the channel capacity,and an optical communication based on single-photon detection is demonstrated.Compared with the traditional PPM coding,polarized PPM coding system has better capability of suppressing the background noise,and the information carried by each pulse is improved by 50%.2.On the basis of polarized PPM coding,optical vortex beam serial coding(OAM PPM coding)and parallel coding(OAM-pair PPM coding)based on single-photon detection are proposed.One pair of orthogonal polarized light is replaced by multiple pairs of optical vortex beams,PPM is added on the basis of orbital angular momentum(OAM)coding to expand the channel capacity under the condition of limited OAM states and to suppress the influence of dead time.3.An optical vortex beam communication based on time-correlated single-photon camera image recognition is demonstrated.Compared with traditional camera,the time information is added for coding to expand channel capacity and the system sensitivity is greatly improved.There are 2^NM combinations of M-ary PPM and N different OAM states,and the channel capacity is M times of OAM shift keying.The image recognition decoding method is demonstrated in the case of four time slots and two kinds of optical vortex beam multiplexing.An optical vortex beam communication with high data rate and high accuracy can be realized through computer vision training.4.A portable integration system of time comparison,optical ranging and communication(TRC)based on single-photon detection is invented for the application requirements of space gravitational wave detection mission.A~1.05 km free-space asynchronous two-way link is constructed and optical communication with the data rate of~195.3 kbps is realized.Under the condition of 3×10~4 counts per second(cps)background noise and the signal light intensity of 1.4 photons per pulse at the receiver,the TRC realizes optical communication with 7.7×10^-5 BER,48.3 mm ranging uncertainty and 162.4 ps time comparison precision.The TRC provides a miniaturization solution for ultra-long distance inter-satellite communication,time comparison and ranging for the space gravitational wave detectors.