Research On Schemes Of Realizing Logic Gate And Secure Transmission In Optical Domain

Due to the limitation of its physical mechanism,microelectronics technology has a bottleneck in data processing speed.Optical signal processing technology can realize the change processing of information in the optical domain and has the ability of high-speed information processing.As the core part of optical signal processing technology,optical signal logic has been applied in many fields.In particular,XOR logic operation can realize the encryption of information by using its reciprocal characteristic,and it has the potential of high efficiency and low operation complex.Therefore,the design of optical logic gate and its application in encryption have great research value.This thesis investigates the scheme of the high-speed optimal logic signal and its application in secure communication system.The main research work is as follows:(1)Combined with the classical Young's double-slit interference experiment,the concept of quasi double-slit interference is introduced.And on this basis,a logic implementation scheme of optical domain signal based on dual-drive Mach-Zehnder external modulator structure is proposed,which generates the required light intensity by controlling the phase difference of two coherent beams.In addition,the parameters and performance of six basic optical logic gates,such as AND,OR,NAND,NOR,XNOR,XOR are optimized.The implementation process of six basic optical signal logic operations at 32Gbit/s signal rate is successfully verified in the experiment.The feature of the scheme is that the basic optical logic signals can be realized by using only a simple dual-drive Mach-Zehnder modulator,and up to 24 kinds of logic signals can be reconstructed by using a set of equipment.In addition,when the bandwidth of modulator and detector is high enough,the logic signal rate of this scheme can reach 100 Gbit/s.In summary,the proposed design has the characteristics of low cost,reconfiguration and high speed.(2)An optical logic gate based on the non-monotonic property of the transfer curve of the intensity modulator is proposed.By controlling the position of the offset point of the intensity modulator,the conversion from four states to two states is realized,and the parameter configuration of six basic logic gates can be obtained by calculation.On this basis,in order to achieve the best extinction ratio of the logic output signal,the parameters of this scheme are jointly optimized.The waveforms and eye patterns of AND,OR,NAND,NOR,XNOR,and XOR at a rate of 18Gbit/s are verified by experiments.Finally,the thesis studies the influence of the main factors on signal quality.(3)A physical secure optical transmission scheme based on signal camouflage encryption is proposed.By "cutting" the edge of the modulated QPSK signal,it can be disguised as 16QAM signal for transmission.On this basis,the camouflage signal is encrypted by XOR logic,and the signal is transmitted safely through two encryption processes.The simulation platform verifies the effectiveness of the scheme and makes the corresponding performance analysis.The simulation results show that the illegal stealing party cannot receive useful information without knowing the key.