Separation Of Optical Chaotic Signals Based On Optical Reservoir Calculation And Its Applications

Optically pumped spin vertical-cavity surface-emitting laser（OP-Spin-VCSEL）is very sensitive to the disturbance from optical feedback or external injection,and easily generates optical chaotic signals with high dimensional state space,good memory fading and consistency.Global-control parameters are adjustable.Therefore,the chaotic system based on OP-Spin-VCSEL can be used to photon reservoir computing（RC）.The photon reservoir computing based on OP-spin-VCSEL has important potential applications in the prediction of optical chaotic synchronization,speech recognition,optical chaotic secure communication,the separation of optical chaotic signals and so on.In particular,the separation of optical chaotic signal is expected to be potentially applied in multi-channel chaotic secure communication,optical signal processing,multi-target chaotic radar ranging and other fields.At present,most of the previous works focuses on the separation of electrical chaotic signals.In these works,the methods of electrical chaotic signal separation mainly include blind source separation,chaotic synchronization,neural network and so on.However,these proposed methods for chaotic signal separation have some limitations,such as the limitation of chaotic sequence length,parameter mismatch and slow convergence.Compared with electrical chaotic signals,optical chaotic signals have higher dimensions and faster and more complex dynamic behaviors.Therefore,it is more difficult to separate optical chaotic signals by using the above-mentioned methods.In addition,the realization of high-speed optical chaotic secure communication using the traditional optical time-division multiplexing（OTDM）faces many challenges,such as the complex structure for OTDM,the difficult demodulation for encrypted signal,and high cost.The photon RC based on OP-spin-VCSEL is expected to overcome these challenges.Therefore,the main works of this project are presented as follows:（1）The system for the separation of the mixed chaotic signal linearly combined with many beams of optical chaotic signals under the case that the mixing fraction is known in advance or unknown,using the optically pumped spin VCSEL optical reservoir computing system.Here,each group of the mixed optical chaotic signals originate from the chaotic X-PC or Y-PC output from the optically pumped spin-VCSELs operation alone.Two parallel optical reservoirs are formed by the chaotic X-PC and Y-PC emitted by the optically pumped spin-VCSEL.We take the mixed chaotic signal linearly combined with no more than three beams of the chaotic X-PCs or Y-PCs as an example to explore its separation.When the mixing fractions are known as a certain value in advance,two groups of the mixed chaotic signals can be effectively separated by using two parallel reservoirs in single VCSEL-based RC system,and their separated errors characterized by the training errors are no more than0.093.In some cases,when the mixing fractions are unknown,we use two cascaded RCs based on R-Spin-VCSEL to separate each group of the mixed chaotic signals.The mixing fractions can be accurately estimated by using two parallel reservoirs in the RC₁ system based on R-Spin-VCSEL.Using values of the estimated mixing fractions,two groups of the mixed chaotic signals can be effectively separated by two parallel reservoirs in the RC₂system based on R-Spin-VCSEL,and their errors also are no more than 0.093.whether the mixing fraction is unknown or known,in the same way,the mixed chaotic signals linearly combined with more than three beams of optical chaotic signals also can be effectively separated.See Chapter 3 for this part.（2）A new dual-channel OTDM chaotic secure communication system is proposed using two cascaded reservoir layers formed by multiple chaotic polarization components emitted by eight optically pumped Spin-VCSEL.Here,each level of reservoir layer includes four parallel reservoirs,and each parallel reservoir contains two sub-reservoirs.After training in the first cascaded reservoir layers,the training error is far less than 0.1.Each group of chaotic hidden signals in time division multiplexing can be effectively separated.In addition,after training in the second cascaded reservoir layers,the training error is far less than 0.1.The high-quality synchronization between each reservoir in the second cascaded reservoir layers and its corresponding delayed chaotic carrier is realized.The correlation coefficient representing the synchronization quality is greater than 0.97.Under this synchronization condition,the performance of dual-channel OTDM chaotic secure communication with a rate of 4×60Gb/s is discussed.By observing the eye diagram,bit error rate and time trajectory of each decrypted signal,it is found that the eye diagram has a large eye opening and a low bit error rate.Except for one decoded signal,the bit error rate is lower than 6×10^-3,and the others are close to 0.See Chapter 4 for this part.