High-order Laguerre-Gauss polychromatic beams from Bragg-Berry flat optics

Nassiri, Mikaël Ghadimi; Cho, Seong‐Yong; Yoshida, Hiroyuki; Brasselet, Étienne

doi:10.1103/physreva.98.063834

Cited by 9 publications

(1 citation statement)

References 43 publications

(51 reference statements)

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“…Regarding the analysis of Laguerre–Gaussian beams in both monochromatic [ 28 ] and polychromatic cases [ 29 , 30 ], as well as beams passing through turbulent atmosphere [ 31 , 32 ], it is believed that the SOD method has the potential to be applied in these areas. SOD techniques can play a crucial role in identifying and analyzing important regions or features in complex optical wavefronts, including Laguerre–Gaussian beams.…”

Section: Experiments and Analysismentioning

confidence: 99%

A Salient Object Detection Method Based on Boundary Enhancement

Wen

Wang

Zou

et al. 2023

Sensors

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Visual saliency refers to the human’s ability to quickly focus on important parts of their visual field, which is a crucial aspect of image processing, particularly in fields like medical imaging and robotics. Understanding and simulating this mechanism is crucial for solving complex visual problems. In this paper, we propose a salient object detection method based on boundary enhancement, which is applicable to both 2D and 3D sensors data. To address the problem of large-scale variation of salient objects, our method introduces a multi-level feature aggregation module that enhances the expressive ability of fixed-resolution features by utilizing adjacent features to complement each other. Additionally, we propose a multi-scale information extraction module to capture local contextual information at different scales for back-propagated level-by-level features, which allows for better measurement of the composition of the feature map after back-fusion. To tackle the low confidence issue of boundary pixels, we also introduce a boundary extraction module to extract the boundary information of salient regions. This information is then fused with salient target information to further refine the saliency prediction results. During the training process, our method uses a mixed loss function to constrain the model training from two levels: pixels and images. The experimental results demonstrate that our salient target detection method based on boundary enhancement shows good detection effects on targets of different scales, multi-targets, linear targets, and targets in complex scenes. We compare our method with the best method in four conventional datasets and achieve an average improvement of 6.2% on the mean absolute error (MAE) indicators. Overall, our approach shows promise for improving the accuracy and efficiency of salient object detection in a variety of settings, including those involving 2D/3D semantic analysis and reconstruction/inpainting of image/video/point cloud data.

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Section: Experiments and Analysismentioning

confidence: 99%

A Salient Object Detection Method Based on Boundary Enhancement

Wen

Wang

Zou

et al. 2023

Sensors

View full text Add to dashboard Cite

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Liquid‐Crystal‐Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics

et al. 2019

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Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin–orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli‐responsive self‐assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC‐mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC‐based transmissive planar optical elements and chiral LC‐based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.

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Light‐Activated Liquid Crystalline Hierarchical Architecture Toward Photonics

Zheng

et al. 2019

Advanced Optical Materials

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remarkable structure results in a helical-variant dielectric tensor, thus contributing to a natural 1D photonic crystal. [7] It is endowed with a broadband Bragg reflection with a unique circular-polarization selectivity. Blue phase (BP) is another fantastic phase with 3D stacked lattice ( Figure 1D). [8] Such an elegant state-of-matter is energetically preferred in a high chirality system, commonly existing in a narrow temperature range of less than 1 K, between the cholesteric and isotropic phases. It has an exotic arrangement characteristic of LCs, which twists around two helical axes forming cylinders including hierarchically twisted molecular architectures. Such double twisted cylinders are impossible to tile the whole 3D space, which leads to inevitable disclinations and results in frustrated structures.Self-organization is an intrinsic ability of LC molecules. However, the precise control and generation of large-area desirable hierarchical superstructures require state-of-the-art techniques that usually combine the "top-down" microfabrication with the "bottom-up" self-assembly. Here, we review various hierarchical architectures in SLCs, CLCs, and BPLCs, especially recent progresses in light-activated LC hierarchical superstructures, as well as their optics and photonics applications in optics and photonics. In this review, we will see the controllable spatial smectic layer curving via 2D anchoring confinement, 3D topographic confinement, and external field guidance, with which the domain size, shape, orientation, and lattice symmetry of focal conic domain (FCD) arrays are well manipulated. The control of helix direction or fluctuation of CLC layers and the growth of unique fingerprint textures including spiral and wave-like continuous gratings are presented. The 3D manipulation of BPLC hierarchical architecture is accomplished photoalignment and various light-driven azobenzene molecular motors. The construction of these unique hierarchical superstructures brings new opportunities to the design of novel optic and photonic devices. Corresponding applications, including traditional microlens array, beam steering, and more advanced specific optical field generation and LC lasers are comprehensively reviewed as well.

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High-order Laguerre-Gauss polychromatic beams from Bragg-Berry flat optics

Cited by 9 publications

References 43 publications

A Salient Object Detection Method Based on Boundary Enhancement

A Salient Object Detection Method Based on Boundary Enhancement

Liquid‐Crystal‐Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics

Light‐Activated Liquid Crystalline Hierarchical Architecture Toward Photonics

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