1 中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海 201800
2 中国科学院大学材料与光电研究中心,北京 100049
针对具有圆对称结构特征的光束,提出了一种基于高阶准离散汉克尔变换的光束整形算法。与传统Gerchberg-Saxton算法相比,相同条件下,该算法能够在较少的迭代次数内实现快速收敛,并大幅节省计算时间(约100倍),利用该算法设计的衍射光学元件呈圆对称分布,结构简单、更易于加工;此外,设计实验对目标光束整形,验证了该算法的可行性,实验结果光强分布较好,为衍射光学元件的设计和加工提供了重要的指导意义。
物理光学 汉克尔变换 光束整形算法 Gerchberg-Saxton算法 衍射光学元件
1 西安工业大学光电工程学院,陕西 西安 710021
2 西安应用光学研究所,陕西 西安 710065
针对空间相机轻量化、小型化要求,采用一体式环形孔径透镜。由于基底单一和结构紧凑,系统存在色差和球差,引入衍射光学元件和偶次非球面校正像差,而单层衍射光学元件在宽波段存在衍射效率下降等问题,设计了一种端到端式光学-数字联合成像系统,对影响衍射效率主要级次的点扩散函数进行一致性优化,构建出空间不变的点扩散函数模型,为后续图像复原建立复原函数模型,实现退化图像的复原。最终光学-数字联合成像系统工作波段确定为0.45~1 μm,焦距为185 mm,视场为5°,F数为4,遮拦比为0.35,系统总长为67.8 mm。
光学设计 环形孔径 单层衍射光学元件 端到端设计 图像复原 激光与光电子学进展
2024, 61(4): 0411006
Xilin Yang 1,2,3†Md Sadman Sakib Rahman 1,2,3Bijie Bai 1,2,3Jingxi Li 1,2,3Aydogan Ozcan 1,2,3,*
Author Affiliations
Abstract
1 University of California, Los Angeles, Electrical and Computer Engineering Department, Los Angeles, California, United States
2 University of California, Los Angeles, Bioengineering Department, Los Angeles, California, United States
3 University of California, Los Angeles, California NanoSystems Institute (CNSI), Los Angeles, California, United States
As an optical processor, a diffractive deep neural network (D2NN) utilizes engineered diffractive surfaces designed through machine learning to perform all-optical information processing, completing its tasks at the speed of light propagation through thin optical layers. With sufficient degrees of freedom, D2NNs can perform arbitrary complex-valued linear transformations using spatially coherent light. Similarly, D2NNs can also perform arbitrary linear intensity transformations with spatially incoherent illumination; however, under spatially incoherent light, these transformations are nonnegative, acting on diffraction-limited optical intensity patterns at the input field of view. Here, we expand the use of spatially incoherent D2NNs to complex-valued information processing for executing arbitrary complex-valued linear transformations using spatially incoherent light. Through simulations, we show that as the number of optimized diffractive features increases beyond a threshold dictated by the multiplication of the input and output space-bandwidth products, a spatially incoherent diffractive visual processor can approximate any complex-valued linear transformation and be used for all-optical image encryption using incoherent illumination. The findings are important for the all-optical processing of information under natural light using various forms of diffractive surface-based optical processors.
optical computing optical networks machine learning diffractive optical networks diffractive neural networks image encryption Advanced Photonics Nexus
2024, 3(1): 016010
天津大学精密仪器与光电子工程学院光电信息技术教育部重点实验室,天津 300072
提出一种基于计算成像理论的端到端衍射元件设计方法,通过全局性优化方案将光学设计和图像复原作为整体,从而降低前端光学系统的成像质量要求,并利用图像复原算法去除残余像差以简化系统。所提设计方法涵盖光场传播、探测器去噪和图像后处理等关键环节的模型建立与联合优化。该设计方案可用于景深延展的轻薄型衍射元件的设计,且所适用的大景深的简单光学系统具有较高的成像质量。
成像系统 端到端 景深延展 图像复原 衍射元件
Author Affiliations
Abstract
1 Institute of Photonic Chips, University of Shanghai for Science and Technology, Shanghai 200093, China
2 School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
3 Nokia Shanghai Bell Co., Ltd., Shanghai 201206, China
4 College of Medical Instruments, Shanghai University of Medicine and Health Sciences, Shanghai 201318, China
Edge detection for low-contrast phase objects cannot be performed directly by the spatial difference of intensity distribution. In this work, an all-optical diffractive neural network (DPENet) based on the differential interference contrast principle to detect the edges of phase objects in an all-optical manner is proposed. Edge information is encoded into an interference light field by dual Wollaston prisms without lenses and light-speed processed by the diffractive neural network to obtain the scale-adjustable edges. Simulation results show that DPENet achieves F-scores of 0.9308 (MNIST) and 0.9352 (NIST) and enables real-time edge detection of biological cells, achieving an F-score of 0.7462.
diffractive neural network edge detection phase objects Chinese Optics Letters
2024, 22(1): 011102
西安科技大学 通信与信息工程学院, 西安 710600
针对OAM通信系统中相干OAM复用光束的解调技术,提出了一种基于纯振幅型衍射深度神经网络(D2NN)的OAM相干复用解调实现方法。通过数值实验研究了D2NN解调器对四相OAM相干复用波束的解调性能,使用误码率(BER)对其性能进行了表征。为了降低D2NN解调的误码率,提出了一种改进的OAM选择策略。并与纯相位型D2NN解调器进行性能对比,仿真实验结果表明,该方法对四相OAM相干复用波束具有较高的解复用和解调精度有着明显优势,为OAM相干复用通信提供了一种灵活的实时解调方法。
轨道角动量 相干复用 衍射深度神经网络 解调 机器学习 orbital angular momentum coherent multiplexing deep diffractive neural network demodulation machine learning
Author Affiliations
Abstract
1 Nanophotonics Research Center, Institute of Microscale Optoelectronics & State Key Laboratory of Radio Frequency Heterogeneous Integration, Shenzhen University, Shenzhen, China
2 Department of Precision Instruments, Tsinghua University, Beijing, China
3 Center for Optics, Photonics and Lasers, Laval University, Quebec, Canada
4 Research Institute of Intelligent Sensing, Research Center for Humanoid Sensing,Zhejiang Lab, Hangzhou, China
Diffractive optical elements (DOEs) are intricately designed devices with the purpose of manipulating light fields by precisely modifying their wavefronts. The concept of DOEs has its origins dating back to 1948 when D. Gabor first introduced holography. Subsequently, researchers introduced binary optical elements (BOEs), including computer-generated holograms (CGHs), as a distinct category within the realm of DOEs. This was the first revolution in optical devices. The next major breakthrough in light field manipulation occurred during the early 21st century, marked by the advent of metamaterials and metasurfaces. Metasurfaces are particularly appealing due to their ultra-thin, ultra-compact properties and their capacity to exert precise control over virtually every aspect of light fields, including amplitude, phase, polarization, wavelength/frequency, angular momentum, etc. The advancement of light field manipulation with micro/nano-structures has also enabled various applications in fields such as information acquisition, transmission, storage, processing, and display. In this review, we cover the fundamental science, cutting-edge technologies, and wide-ranging applications associated with micro/nano-scale optical devices for regulating light fields. We also delve into the prevailing challenges in the pursuit of developing viable technology for real-world applications. Furthermore, we offer insights into potential future research trends and directions within the realm of light field manipulation.
diffractive optical elements metasurfaces metamaterials Photonics Insights
2023, 2(4): R09