Over the years, researchers have been exploring ways to artificially design chiral structures and materials, namely metamaterials and metasurfaces. They exhibit unique optical properties that can be used for various applications. However, metasurfaces comprise symmetry‐breaking structures that provide a more convenient solution for planar chiral optics regardless of whether they are plasmonic or dielectric. In general, plasmonic chiral metasurfaces are more suitable for applications requiring a high confinement level and substantial optical near‐field enhancement. In contrast, dielectric chiral metasurfaces are ideal for wide operating wavelength ranges and low losses. This review summarizes the recent progress on plasmonic and dielectric chiral metasurfaces. It includes the fundamental concepts, design strategies, and their implementation for applications in holographic displays, imaging and sensing, and detection. Moreover, an overview of chiral metasurfaces to generate the nonlinear effects, hosting bound states in the continuum, and the significant role of machine‐learning‐based design approaches are also discussed. Finally, some future developments are highlighted where chiral metasurfaces are expected to play a vital role.
The video recording–capable compact incoherent digital holographic camera system is proposed. The system consists of the linear polarizer, convex lens, geometric phase lens, and the polarized image sensor. The Fresnel hologram is recorded by this simple configuration in real time. The system parameters are analyzed and evaluated to record a better-quality hologram in a compact form-factor. The real-time holographic recording and its digitally reconstructed video playback are demonstrated with the proposed system.
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An integral imaging microscopy (IIM) system with improved depth-of-field (DoF) using a custom-designed bifocal polarization-dependent liquid-crystalline polymer micro lens array (LCP-MLA) is proposed. The implemented MLA has improved electro-optical properties such as a small focal ratio, high fill factor, low driving voltage, and fast switching speed, utilizing a well-aligned reactive mesogen on the imprinted reverse shape of the lens and a polarization switching layer. A bifocal MLA switches its focal length according to the polarization angle and acquires different DoF information of the specimen. After two elemental image arrays are captured, the depth-slices are reconstructed and combined to provide a widened DoF. The fabricated bifocal MLA consists of two identical polarization-dependent LCP-MLAs with 1.6 mm and f/16 focal ratio. Our experimental results confirmed that the proposed system improves the DoF of IIM without the need for mechanical manipulation.
We demonstrated a 2D/3D switchable mobile display using a polarization-dependent switching liquid crystalline polymeric (LCP) lens array film. In spite of short viewing distance and enough viewing window conditions provided by a small f-number lens for mobile displays, the 3D images when switched to the multi-view 3D mode showed a low crosstalk property owing to the improved lens aberration, as applying an aspherical lens curvature interface between the planar-convex LCP layer and the concave-planar isotropic polymer layer. Both 2D and 3D images were demonstrated based on a 5.5-inch quad high definition mobile display panel, where the binocular crosstalk of the 3D mode was 3.3%.