Research On 3D Point Cloud Encryption And Photonic Reservoir Computing Based On Nonlinear Characteristics Of Semiconductor Optical Devices

After more than 60 years of constant advancement,semiconductor optical devices have become the core cornerstone to sustain the continuous innovation and upgrading of the new generation information technology,and their abundant optical nonlinear characteristics have been quietly dedicated to the fields of optical communication,optical encryption and optical computing.Among the numerous semiconductor optical devices,semiconductor laser(SCL)has become one of the most popular and mature nonlinear optical devices in research and application,relying on its advantages of wide bandwidth,high speed,small loss,low manufacturing cost,and long working life.As an important research focus of SCL,the vertical cavity surface emitting laser(VCSEL)has been widely applied in the fields of secure communication,photonic neural mimicry and lidar with its various nonlinear dynamic characteristics.With the increasingly prosperous research of spintronics,spin polarized VCSEL(SPVCSEL)has more advantages than traditional VCSEL in terms of polarization stability,control,modulation dynamics and threshold current.However,the nonlinear dynamics research of SPVCSEL is relatively rare and mainly converges on the single SPVCSEL without external disturbance,and the research of SPVCSEL under external disturbance is still scarce.Therefore,this thesis relies on the mutually coupled mechanism of two SPVCSELs to investigate the nonlinear dynamics properties of mutually coupled SPVCSELs(MCSPVCSELs),and explore the performance of time-delay signature(TDS)suppression and bandwidth enhancement to obtain the high-quality chaotic output.While the high-quality chaos is often utilized in the indagation blue ocean of image encryption to ensure the privacy and security of image information.However,the three dimensional(3D)point cloud,which is more comprehensive and close to reality than the traditional two-dimensional image,and shines brilliantly in emerging fields such as unmanned driving and smart cities,also faces the security problem of its privacy being easily leaked,while the research on 3D point cloud encryption and its privacy protection is extremely poor.Therefore,this thesis studies the optical encryption scheme of 3D point cloud based on the high-quality chaos of double optical feedback(DOF)MCSPVCSELs.In addition,the reservoir computing(RC)has shown its unique advantages in time series prediction and target recognition tasks by relying on its high information processing rate,simple algorithm and strong computational efficiency.Currently,the research of photonic RC is mainly focused on SCL.Compared with SCL,the semiconductor optomechanical microcavity(OMMC)has incomparable advantages in device size,compatibility of complementary metal oxide semiconductor(CMOS),manufacturing cost,power consumption,scalability and integration with the aid of photonic integrated technology(PIT).At present,the research of photonic RC based on semiconductor photonic integrated devices is still exceedingly scarce.Hence,this thesis relies on the semiconductor OMMC with rich nonlinear characteristics to construct the photonic RC based on semiconductor OMMC,and actually combines the stock market data and COVID-19 case data with complex nonlinear characteristics to study the prediction ability of semiconductor OMMC photonic RC.The research content and results of this thesis are as follows:(1)The theoretical model of MCSPVCSELs under optical pumping is constructed,and the nonlinear dynamic characteristics of MCSPVCSELs are studied,while the method of TDS suppression and bandwidth enhancement simultaneously is explored.Numerous nonlinear dynamic behaviors containing the state of steady,period,period-doubling,and chaos have been observed in the bifurcation diagram,revealing the period-doubling route to chaos.The characteristics of these dynamic behaviors are analyzed in detail along with clarifying the physical mechanism of their occurrence.The influences of laser parameters on the dynamic behaviors are indagated through mapping diagrams,and the results show that both the pump intensity and pump ellipticity are crucial to the complicated dynamic behaviors including chaos.Additionally,the increase of the coupling strength,coupling time delay,and frequency detuning have beneficial impacts to chaos while the spin relaxation rate has a harmful effect on the contrary.The comparison results on different parameter planes of MCSPVCSELs illustrate that the TDS suppression and bandwidth enhancement can be achieved simultaneously when coupling strength,frequency detuning and pump strength are relatively large.Therefore,the MCSPVCSELs have an application prospect in chaos-based fields.(2)In allusion to the privacy and security problems in 3D point cloud,a 3D point cloud optical encryption scheme based on MCSPVCSELs with DOF is proposed and implemented,and the performance of the encryption mechanism against 3D point cloud classification algorithm is explored.Firstly,the optical chaotic characteristics of MCSPVCSELs with DOF are studied and applied to the permutation and diffusion encryption mechanism of 3D point cloud.The nonlinear dynamics and complexity results demonstrate that the MCSPVCSELs with DOF have high chaotic complexity and can provide tremendously large key space.All the test-sets of Model Net40 dataset containing 40 object categories are encrypted and decrypted by the proposed 3D point cloud encryption scheme,and then the classification results of 40 object categories for original,encrypted,and decrypted 3D point cloud are entirely enumerated through the Point Net++.Intriguingly,the class accuracies of the encrypted point cloud are nearly all equal to 0.0000%except for the plant class with 100.0000%,indicating the encrypted point cloud cannot be classified and identified.The decryption class accuracies are very close to the original class accuracies.Therefore,the classification results verify that the proposed 3D point cloud privacy protection scheme is practically feasible and remarkably effective.Additionally,the encryption and decryption results show that the encrypted point cloud images are ambiguous and unrecognizable,while the decrypted point cloud images are identical to original images.Moreover,this thesis improves the security analysis via analyzing eight 3D point cloud geometric features.Eventually,six security analysis results validate that the proposed privacy protection scheme has high security level and good privacy protection effect for 3D point cloud.(3)The theoretical model of semiconductor OMMC photonic RC is proposed and constructed,and the prediction capability of semiconductor OMMC photonic RC is evaluated through stock market(SM)forecast and coronavirus disease 2019(COVID-19)epidemic forecast.The long-term closing prices of four representative stock indexes are accurately forecast with small prediction errors in this thesis,and the forecasting results with distinct characteristics are exhibited in the mature SM and emerging SM separately.The work in this thesis offers solutions and suggestions for surmounting the concept drift phenomenon(CDP)in stock market environment.The comprehensive influence of RC parameters on forecasting performance are displayed via the mapping diagrams,while some intriguing results indicate that the mature SM are more sensitive to the variation of photonic RC parameters than the emerging SM.Furthermore,a long-term six-month COVID-19 pandemic forecast in second half of 2021 is successfully implemented,the testing-dataset forecast results of new cases,new deaths,cumulative cases,and cumulative deaths for six countries in this thesis demonstrate that the forecasted blue curves are awfully close to the real red curves with exceedingly small forecast errors.The forecast results commendably reflect the variations of the actual case data,revealing the different epidemic transmission laws in developed and developing countries.Therefore,this thesis contributes a novel photonic RC model for SM forecast and COVID-19 pandemic forecast in the nanophotonic field,and provides a new prototype system for more applications in the intelligent information processing field.