Research On Secure Communications Using Chaotic Laser And Optical Vortices

Due to the rapid development of semiconductor technology and information technology,the communication capacity of optical communications has been greatly increased,and the reliability of communications has also been highly guaranteed.However,the endless stream of information leakage has exposed the secure risks of communications,and the secure communication technology has become a research hot topic.Secure communications based on chaotic laser,which are encrypted at the physical layer,have attracted wide attention because of the high security and high data rate.Additionally,optical communication systems based on optical vortics carrying orbital angular momentum(OAM)also show security due to the unique helical phase structure and distinct detection feature.In this thesis,we focus on the security of optical communication systems.The security of communication systems based on chaotic laser and optical vortices is experimentally studied.The details are as follows:(1)The basic characteristics of chaos,several common methods of chaotic laser generation and chaos synchronization are introduced.Then the chaotic laser generation and synchronization system based on nonlinear optoelectronic delay feedback is built,and highspeed secure communications are realized in two types of short-distance multimode fibers.The security of signal transmission with two modulation formats is demonstrated in the experiment.(2)The basic characteristics,generation methods and detection techniques of optical vortices are briefly introduced.The single and multiple optical vortex generation and detection system in free space is built.The influence on OAM power spectrum measurement is experimentally studied when the light field is partially blocked.The obtained results indicate the physical layer secure properties of free-space communication systems based on optical vortices.(3)The chaos generation and synchronization principle in an optical feedback system are introduced and simulated.Then two independent chaotic laser sources are built and the highefficiency chaotic synchronization is realized by optical injection.After that,the chaotic laser systems are combined with spatial multiplexing based on two optical vortices.Two high-speed independent data information channels are transmitted with security.The experimental results show that the communication system can not only improve the communication capacity,but also greatly improve the security of communications.