Multiparameter performance monitoring of pulse amplitude modulation channels using convolutional neural networks

A designed visual geometry group(VGG)-based convolutional neural network(CNN)model with small computational cost and high accuracy is utilized to monitor pulse amplitude modulation-based intensity modulation and direct detection channel performance using eye diagram measurements.Experimental results show that the proposed technique can achieve a high accuracy in jointly monitoring modulation format,probabilistic shaping,roll-off factor,baud rate,optical signal-to-noise ratio,and chromatic dispersion.The designed VGG-based CNN model outperforms the other four traditional machine-learning methods in different scenarios.Furthermore,the multitask learning model combined with MobileNet CNN is designed to improve the flexibility of the network.Compared with the designed VGG-based CNN,the MobileNet-based MTL does not need to train all the classes,and it can simultaneously monitor single parameter or multiple parameters without sacrificing accuracy,indicating great potential in various monitoring scenarios.

Object pose and surface material recognition using a single-time-of-flight camera

We propose an approach for recognizing the pose and surface material of diverse objects,leveraging diffuse reflection principles and data fusion.Through theoretical analysis and the derivation of factors influencing diffuse reflection on objects,the method concentrates on and exploits surface information.To validate the feasibility of our theoretical research,the depth and active infrared intensity data obtained from a single time-of-flight camera are initially combined.Subsequently,these data undergo processing using feature extraction and lightweight machine-learning techniques.In addition,an optimization method is introduced to enhance the fitting of intensity.The experimental results not only visually showcase the effectiveness of our proposed method in accurately detecting the positions and surface materials of targets with varying sizes and spatial locations but also reveal that the vast majority of the sample data can achieve a recognition accuracy of 94.8%or higher.

Integrated solid-state lidar employing orthogonal polarizations and counterpropagation[Invited]

Light detection and ranging(lidar)has attracted significant interest as a sensing technology for its ability to achieve highresolution imaging and wide-angle perception.However,conventional lidar systems,built with separate components,are often bulky,expensive,complex,and prone to instability.In contrast,solid-state lidar,based on silicon photonics technology,offers a solution with its compact size,less expense,low energy consumption,and improved reliability.However,achieving precise beam steering remains a critical challenge for integrated lidar systems.Various methods have been demonstrated for beam steering,which is one of the simplest and most efficient approaches that utilize wavelength tuning with a grating coupler antenna.In this review,we introduce the fundamental principle of optical phased array for beam steering and provide an overview of the recent advancements in integrated solid-state lidars utilizing orthogonal polarizations and counterpropagation to enhance beam-steering range and angular resolution.

The Logic of Contingency in China＇s Insistence on the Non-interference Principle

China＇s insistence on the non-interference principle has been increasingly inconsistent. While China＇s concern with sovereignty, regime security, and legitimacy, as well as its developing country identity, have pushed it to continue its insistence on the principle of non-interference, China＇s further adaptation to the international system, increasing engagement in intemational institutions, and new identity as a responsible power have led China to drag its feet on the same principle. To reconcile these competing forces, China has to make concessions, namely, setting preconditions to legitimize intervention, designing a sovereignty-first solution, and/or complementing the non-interference principle with alternative principles. China＇s application of the non-interference principle has thus been made contingent. It is more inflexible at one end of a spectrum and more flexible at the other end, with China＇s foreign policies shifting back and forth between them.