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1 Issue (s), 4 Article (s)
Vol. 12, Iss.5—May.1, 2024 • pp: 876-911 Spec. pp:
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Research ArticlesVol. 12, Iss.5-May..1,2024
Image Processing and Image Analysis
Complex transmission matrix retrieval for a highly scattering medium via regional phase differentiationQiaozhi He, Rongjun Shao, Yuan Qu, Linxian Liu, Chunxu Ding, and Jiamiao Yang
Accurately measuring the complex transmission matrix (CTM) of the scattering medium (SM) holds critical significance for applications in anti-scattering optical imaging, phototherapy, and optical neural networks. Non-interferometric approaches, utilizing phase retrieval algorithms, can robustly extract the CTM from the speckle patterns formed by multiple probing fields traversing the SM. However, in cases where an amplitude-type spatial light modulator is employed for probing field modulation, the absence of phase control frequently results in the convergence towards a local optimum, undermining the measurement accuracy. Here, we propose a high-accuracy CTM retrieval (CTMR) approach based on regional phase differentiation (RPD). It incorporates a sequence of additional phase masks into the probing fields, imposing a priori constraints on the phase retrieval algorithms. By distinguishing the variance of speckle patterns produced by different phase masks, the RPD-CTMR can effectively direct the algorithm towards a solution that closely approximates the CTM of the SM. We built a prototype of a digital micromirror device modulated RPD-CTMR. By accurately measuring the CTM of diffusers, we achieved an enhancement in the peak-to-background ratio of anti-scattering focusing by a factor of 3.6, alongside a reduction in the bit error rate of anti-scattering image transmission by a factor of 24. Our proposed approach aims to facilitate precise modulation of scattered optical fields, thereby fostering advancements in diverse fields including high-resolution microscopy, biomedical optical imaging, and optical communications. Accurately measuring the complex transmission matrix (CTM) of the scattering medium (SM) holds critical significance for applications in anti-scattering optical imaging, phototherapy, and optical neural networks. Non-interferometric approaches, utilizing phase retrieval algorithms, can robustly extract the CTM from the speckle patterns formed by multiple probing fields traversing the SM. However, in cases where an amplitude-type spatial light modulator is employed for probing field modulation, the absence of phase control frequently results in the convergence towards a local optimum, undermining the measurement accuracy. Here, we propose a high-accuracy CTM retrieval (CTMR) approach based on regional phase differentiation (RPD). It incorporates a sequence of additional phase masks into the probing fields, imposing a priori constraints on the phase retrieval algorithms. By distinguishing the variance of speckle patterns produced by different phase masks, the RPD-CTMR can effectively direct the algorithm towards a solution that closely approximates the CTM of the SM. We built a prototype of a digital micromirror device modulated RPD-CTMR. By accurately measuring the CTM of diffusers, we achieved an enhancement in the peak-to-background ratio of anti-scattering focusing by a factor of 3.6, alongside a reduction in the bit error rate of anti-scattering image transmission by a factor of 24. Our proposed approach aims to facilitate precise modulation of scattered optical fields, thereby fostering advancements in diverse fields including high-resolution microscopy, biomedical optical imaging, and optical communications.
Photonics Research
- Publication Date: Apr. 08, 2024
- Vol. 12, Issue 5, 876 (2024)
Optoelectronics
Target-adaptive optical phased array lidarYunhao Fu, Baisong Chen, Wenqiang Yue, Min Tao, Haoyang Zhao, Yingzhi Li, Xuetong Li, Huan Qu, Xueyan Li, Xiaolong Hu, and Junfeng Song
Lidar based on the optical phased array (OPA) and frequency-modulated continuous wave (FMCW) technology stands out in automotive applications due to its all-solid-state design, high reliability, and remarkable resistance to interference. However, while FMCW coherent detection enhances the interference resistance capabilities, it concurrently results in a significant increase in depth computation, becoming a primary constraint for improving point cloud density in such perception systems. To address this challenge, this study introduces a lidar solution leveraging the flexible scanning characteristics of OPA. The proposed system categorizes target types within the scene based on RGB images. Subsequently, it performs scans with varying angular resolutions depending on the importance of the targets. Experimental results demonstrate that, compared to traditional scanning methods, the target-adaptive method based on semantic segmentation reduces the number of points to about one-quarter while maintaining the resolution of the primary target area. Conversely, with a similar number of points, the proposed approach increases the point cloud density of the primary target area by about four times.Lidar based on the optical phased array (OPA) and frequency-modulated continuous wave (FMCW) technology stands out in automotive applications due to its all-solid-state design, high reliability, and remarkable resistance to interference. However, while FMCW coherent detection enhances the interference resistance capabilities, it concurrently results in a significant increase in depth computation, becoming a primary constraint for improving point cloud density in such perception systems. To address this challenge, this study introduces a lidar solution leveraging the flexible scanning characteristics of OPA. The proposed system categorizes target types within the scene based on RGB images. Subsequently, it performs scans with varying angular resolutions depending on the importance of the targets. Experimental results demonstrate that, compared to traditional scanning methods, the target-adaptive method based on semantic segmentation reduces the number of points to about one-quarter while maintaining the resolution of the primary target area. Conversely, with a similar number of points, the proposed approach increases the point cloud density of the primary target area by about four times.
Photonics Research
- Publication Date: Apr. 12, 2024
- Vol. 12, Issue 5, 904 (2024)
Surface Optics and Plasmonics
Simplistic framework of single-pixel-programmable metasurfaces integrated with a capsuled LED arrayYuxi Li, Jiafu Wang, Sai Sui, Ruichao Zhu, Yajuan Han, Hongya Chen, Xinmin Fu, Shaojie Wang, Cunqian Feng, and Shaobo Qu
Coding metasurfaces can manipulate electromagnetic wave in real time with high degree of freedom, the fascinating properties of which enrich the metasurface design with a wide range of application prospects. However, most of the coding metasurfaces are designed based on external excitation framework with the wired electrical or wireless light control devices, thus inevitably causing the interference with electromagnetic wave transmission and increasing the complexity of the metasurface design. In this work, a simplistic framework of single-pixel-programmable metasurfaces integrated with a capsuled LED array is proposed to dynamically control electromagnetic wave. The framework fully embeds the photoresistor in the meta-atom, controlling the LED array to directly illuminate the photoresistor to modulate the phase response. With this manner, the complex biasing network is transformed to the universal LED array, which means the physical control framework can be transformed to a software framework, and thus the functions of the metasurface can be freely manipulated by encoding the capsuled LED array avoiding mutual coupling of adjacent meta-atoms in real time. All the results verify that the far-field scattering pattern can be customized with this single-pixel-programmable metasurface. Encouragingly, this work provides a universal framework for coding metasurface design, which lays the foundation for metasurface intelligent perception and adaptive modulation.Coding metasurfaces can manipulate electromagnetic wave in real time with high degree of freedom, the fascinating properties of which enrich the metasurface design with a wide range of application prospects. However, most of the coding metasurfaces are designed based on external excitation framework with the wired electrical or wireless light control devices, thus inevitably causing the interference with electromagnetic wave transmission and increasing the complexity of the metasurface design. In this work, a simplistic framework of single-pixel-programmable metasurfaces integrated with a capsuled LED array is proposed to dynamically control electromagnetic wave. The framework fully embeds the photoresistor in the meta-atom, controlling the LED array to directly illuminate the photoresistor to modulate the phase response. With this manner, the complex biasing network is transformed to the universal LED array, which means the physical control framework can be transformed to a software framework, and thus the functions of the metasurface can be freely manipulated by encoding the capsuled LED array avoiding mutual coupling of adjacent meta-atoms in real time. All the results verify that the far-field scattering pattern can be customized with this single-pixel-programmable metasurface. Encouragingly, this work provides a universal framework for coding metasurface design, which lays the foundation for metasurface intelligent perception and adaptive modulation.
Photonics Research
- Publication Date: Apr. 12, 2024
- Vol. 12, Issue 5, 884 (2024)
Surface Optics and Plasmonics
Terahertz sensing with a 3D meta-absorbing chip based on two-photon polymerization printingXueer Chen, Longfang Ye, and Daquan Yu
The narrowband meta-absorbers exhibit significantly enhanced electromagnetic confinement capabilities, showcasing broad application prospects in sensing fields. They can be applied for biomarker detection, chemical composition analysis, and monitoring of specific gas in the environment. In this work, we propose a 3D meta-absorber with an out-of-plane plasma mechanism based on a two-photon printing system. Compared to the conventional fabrication of a metal-insulator-metal 2D meta-absorber, the 3D absorber is composed of a metal layer and a resin layer from top to bottom; its manufacturing process is simpler, only including two-photon printing and magnetron sputtering deposition. A noticeable absorbing resonance appears at 0.3142 THz with perfect absorbance with a high
Photonics Research
- Publication Date: Apr. 12, 2024
- Vol. 12, Issue 5, 895 (2024)
Ultracompact silicon on-chip polarization controllerOn the Cover
Vol. 12, Issue 2, 183 (2024)
Vol. 11, Issue 12, 2194 (2023)
Vol. 12, Issue 1, 70 (2024)
Optical metasurfaces: fundamentals and applications
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Multidimensional optical tweezers synthetized by rigid-body emulated structured light
Vol. 11, Issue 9, 1524 (2023)
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