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This publisher's note contains corrections to Opt. Lett.48, 795 (2023)10.1364/OL.481980.
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In this Letter, we report a dual-twist template imprinting method to fabricate subwavelength-period liquid crystal polarization gratings (LCPGs). In other words, the period of the template must be reduced to 800â nm-2â µm, or even smaller. To overcome the inherent problem that the diffraction efficiency shrinks as the period decreases, the dual-twist templates were optimized by rigorous coupled-wave analysis (RCWA). With the help of the rotating Jones matrix to measure the twist angle and thickness of the LC film, the optimized templates were fabricated eventually, and the diffraction efficiencies were up to 95%. Therefore, subwavelength-period LCPGs with a period of 400-800â nm were imprinted experimentally. Our proposed dual-twist template provides the possibility for fast, low-cost, and mass fabrication of large-angle deflectors and diffractive optical waveguides for near-eye displays.
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Tunable metasurfaces provide a compact and efficient strategy for optical active wavefront shaping. Varifocal metalens is one of the most important applications. However, the existing tunable metalens rarely serves broadband wavelengths restricting their applications in broadband imaging and color display due to chromatic aberration. Herein, an electrically tunable polarization-multiplexed achromatic metalens integrated with twisted nematic liquid crystals (TNLCs) in the visible region is demonstrated. The phase profiles at different wavelengths under two orthogonal polarization channels are customized by the particle swarm optimization algorithm and matched with the dielectric metaunits database to achieve polarization-multiplexed achromatic performance. By combining the broadband linear polarization conversion ability of TNLC, the tunability of varifocal achromatic metalens is realized by applying different voltages. Further, the electrically tunable customized dispersion-manipulated metalens and switchable color metaholograms are demonstrated. The proposed devices will accelerate the application of metasurfaces in broadband zoom imaging, AR/VR displays and spectral detection.
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Metasurfaces open up new avenues for designing planar optics, enabling compact dynamic metadevices. Numerous dynamic strategies have been proposed, among which liquid crystal (LC) based metasurfaces are expected due to the maturity of LC materials. However, existing schemes rarely exploit the polarization manipulation capabilities of metasurfaces and the limited performance hinders the development of practical addressable devices. Here, we demonstrate an electrically tunable multifunctional polarization-dependent metasurface integrated with LCs in the visible range. By a combination of the helicity-dependent metasurface and the birefringent LCs, continuous intensity tuning and switching of two helicity channels are realized. Electrically tunable mono- and multicolor switchable metaholograms and dynamic varifocal metalenses are demonstrated with a simple and performance-enhancing integration scheme. Further, electrically addressable dynamic metasurfaces are achieved. The proposed modulation and integration schemes pave the way for addressable dynamic metasurface devices in various applications, such as space light modulators, light detection and ranging systems, and holographic displays.
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In this Letter, transverse and longitudinal liquid crystal bifocal lenses (LCBLs) are proposed to continuously control the relative intensity of two foci through a simple polarization control. The modulation of a LCBL comes from the geometric phase control and is designed through the principle of holography, where the object wave is a light field from two foci respectively formed by the left-circular polarized (LCP) and right-circular polarized (RCP) light, and the reference wave is the incident plane wave. Constructed millimeter-scale LCBLs are verified experimentally, and the foci are precisely formed at the preset plane. Besides, the relative intensity can be easily controlled with different weights of LCP and RCP light. The proposed strategy overcomes the shortcomings of previous bifocal lenses, such as a complex design method, a long optimization time, and an unchangeable relative intensity, and it is expected to find potential applications in parallel optical processing and optical interconnections.
