Research Of High Speed Key Distribution Theory And Key Technologies Of Chaos Synchronization System Based On VCSELs

With the rapid development of science and technology,the demands for communication security and data processing efficiency are increasing.Optical technology is more widely used than electronic technology in data transmission,at the same time,other applications based on optics are also booming.Delay-based semiconductor laser systems can generate rich dynamical behaviors,which can be used for chaotic communications,key distribution,and reservoir computing.In this thesis,we have studied the following three aspects:1.In this thesis,Mean Permutation Entropy?MPE?is proposed as a method to evaluate the complexity of multi-delay laser chaos systems.A multi-delay ring network based on mutually coupled VCSELs is designed to generate complexity-enhanced multi-channel laser chaos outputs.The influence of tunable system parameters on chaos complexity is analyzed quantitatively by the proposed MPE.For direct comparison,the complexity of chaos in a ring network of VCSELs coupled with single delay is also considered.The quantification method of autocorrelation time is also used to analyze the effects of the injection current on the chaotic complexity of the systems for the purpose of comparison.The results show that the chaotic complexity of the multi-delay system is obviously higher than that of the single-delay system,and the validity of MPE is also proved.In addition,we find that high-complexity chaotic outputs of multi-delay system can be obtained in a much wider parameter space of frequency detuning and coupling strength.Finally,we analyze the correlation properties between the six chaotic outputs of three VCSELs,and find that the correlation of same modes of different VCSELs is low at low coupling strength,and correlation of different modes of different VCSELs remains low throughout the entire parameter region.2.A key distribution scheme based on the chaotic synchronization of VCSELs system is proposed.Chaotic signals generated by optical injection drive two identical VCSELs to achieve chaotic synchronization for key distribution.Considering that the attacker may eavesdrop on fiber,an illegal user is introduced to the system.Under appropriate condition,the synchronization coefficient between two legitimate users can reach 0.99,and the synchronization coefficient between the illegal user and legitimate users is only 0.74.By the single-threshold quantization,the bit error rate of key between legitimate users is as low as 0.33%,and the bit error rate between the illegal user and legitimate users is higher than 10.0%.By the double-threshold quantization,the bit error rate between legitimate users can be reduced to 10^-6 or even lower.The key distribution rate of the system can reach 4Gbit/s.In addition,we also analyze the effects of parameter mismatch on bit error rate and the randomness of keys.3.The reservoir computing based on the semiconductor laser system with optical feedback is investigated.A single node reservoir computing has three layers.The data is modulated into the reservoir system in the input layer.The data is dynamically responded in the reservoir layer.The output weights are obtained through linear regression in the output layer.The parameter conditions of the reservoir are studied by a time series prediction task as well as a waveform identification task.In addition,the output dynamics of the reservoir system without input data are analyzed.It is found that when the system is in a steady state or periodic state in the absence of data input,better performance can be achieved for both prediction tasks and identification tasks.