In addition to CPL detection, ultracompact polarimetric detection and imaging systems are highly desirable for full polarization state measurements in various applications such as communication 27, 28, remote sensing 29, polarization imaging 30, and biological diagnostics 31, 32, 33. To date, the realization of ultracompact CPL detection devices with simultaneously high extinction ratios and optical efficiencies is still challenging. However, the CPERs of these surfaces are still limited (up to eight). To improve the optical efficiency, chiral dielectric metasurface structures have been achieved in experiments 13, 19 with optical efficiencies as high as 90%. Compared with 3D chiral metamaterials, metasurface structures are easier to fabricate and more compatible with on-chip manufacturing technologies however, the chiral plasmonic metasurfaces experimentally demonstrated so far usually suffer from low circular polarization extinction ratios (CPERs) (less than ~ 5) and limited optical efficiency in experiments (20–50%). More recently, planar (or 2D) chiral plasmonic metasurface structures composed of gammadions 16, Z-shaped antennas 17, spiral slots 18, and even stacks of twisted planar and achiral structures (crosses 14, nanorods 15, 23, etc.) with chiro-optical responses have been reported. However, the fabrication of these complex 3D structures requires stringent process control, and scalability is challenging. For example, artificial three-dimensional (3D) metamaterials have been produced based on chiral L-shaped 22, helical 20, 24, 25, 26, and spiral 21 nanostructures to differentiate the handedness of CPL. Compared with organic chiral molecules, nanostructure-based devices generally exhibit superior stability in ambient conditions, fast response time, and high fidelity. Recent developments in nanotechnology and nanophotonics have enabled ultracompact solid-state CPL detection 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 (see Supplementary Table S1). Organic chiral molecules have been proposed for miniaturization of CPL detection devices, such as liquid crystals (LCs) 9, 10, chiral dyes 11, and helicene-based chiral semiconductor transistors 12. Traditionally, CP light detection requires multiple bulky optical elements such as polarizers, waveplates, and mechanically rotating components 8, which poses fundamental limitations for device miniaturization, robust system integration, and high-speed operation. With the advantages of easy on-chip integration, ultracompact footprints, scalability, and broad wavelength coverage, our designs hold great promise for facilitating chip-integrated polarimeters and polarimetric imaging systems for quantum-based optical computing and information processing, circular dichroism spectroscopy, biomedical diagnosis, and remote sensing applications.Ĭircularly polarized light (CPL) has been widely used in quantum communication 1, quantum computing 2, 3, circular dichroism (CD) spectroscopy 4, and polarimetric imaging and sensing 5, 6, 7. We also monolithically integrated the microscale circular polarization filters with linear polarization filters to perform full-Stokes polarimetric measurements of light with arbitrary polarization states. We experimentally demonstrated submicron-thick circularly polarized light filters with peak extinction ratios up to 35 and maximum transmission efficiencies close to 80% at near-infrared wavelengths (the best operational wavelengths can be engineered in the range of 1.3–1.6 µm). Herein, we report bioinspired chiral metasurfaces with both strong chiral optical effects and low insertion loss. Chiral metamaterials and metasurfaces facilitate ultracompact devices for circularly polarized light generation, manipulation, and detection. The manipulation and characterization of light polarization states are essential for many applications in quantum communication and computing, spectroscopy, bioinspired navigation, and imaging.
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