Simultaneous Surface Display and Holography Enabled by Flat Liquid Crystal Elements

Abstract

As a fundamental material in the current mainstream display technology, liquid crystal (LC) exhibits excellent properties including controllable and reconfigurable LC orientation, high‐efficiency pure‐phase modulation, active tunability, etc., and becomes one of the most attractive candidates for the development of next‐generation flat optical devices. Current LC elements are suffering from the single functionality as only one type of the optical manipulation is involved. Integrating several functions together brings great flexibility and high integration but remains an urgent task. Here, flat LC elements are proposed to simultaneously accomplish near‐field display and far‐field holography. The anisotropic nature of the LC allows a complex amplitude modulation with a sinusoidal variation, promising a continuous amplitude change, and a binary phase modulation. Specifically, several two‐channel LC elements are experimentally demonstrated, which simultaneously generate a grayscale pattern at sample surface and project an independent holographic image in the far field. Furthermore, the position and spatial multiplexing methodologies are introduced to further improve the information capacity. The proposed LC elements with simple anisotropic structure and large fabrication size can empower the multifunctional design and have promising prospects in information multiplexing, image displaying, data storage, etc.

Optical Steganography via Programmable Anchoring Boundary of Soft Materials

“…Images, consisting of optical patterns with color profiles or spatially varying intensity, play an important role in transferring information such as documents, labels, identification codes, and so on. [1][2][3] It has been proven that a fade-free, environmentally friendly, and stable imaging system can be achieved and far field, [33,34] that near-field grayscale patterns and far-field holography images can be achieved by manipulating the complex transmission coefficient of light. By ingeniously designing the composition of LCs and the anchoring boundary, [35] propagation-direction-dependent images are reconstructed in tunable broadband with reversible switching behaviors, facilitating the advanced optical information storage.…”

“…[ 30 ] However, the traditional LC elements are generally limited to the device functionality that only one type of manipulation can be realized in single channel. [ 31,32 ] Recently, two‐channels LC elements have been demonstrated which simultaneously modulate the light field in both near and far field, [ 33,34 ] that near‐field grayscale patterns and far‐field holography images can be achieved by manipulating the complex transmission coefficient of light. By ingeniously designing the composition of LCs and the anchoring boundary, [ 35 ] propagation‐direction‐dependent images are reconstructed in tunable broadband with reversible switching behaviors, facilitating the advanced optical information storage.…”

Shortening Focal Length of 100‐mm Aperture Flat Lens Based on Improved Sagnac Interferometer and Bifacial Liquid Crystal

“…[13,14] Alternatively, planar optical components based on liquid crystal (LC) materials also have great potential in large-size applications, known as LC Pancharatnam-Berry Optical Elements (LCPBOE). [15][16][17][18][19][20][21][22][23] The functionalities of LCPBOE rely on the birefringent nature of LC [24][25][26] and the modulation of PB phase, also known as geometric phase. [9,[27][28][29] For an LC lens, the streamlines (tangent curves) of the LC molecular axes resemble the well-known catenary of equal strength, which imparts a continuous phase to the LC device and achieves high diffraction efficiency closing to the theoretical limit.…”

High‐Efficiency Dual‐Band Metasurface with Independent Multifold Geometric Phases

“…[22][23][24] In general, two methods are used to implement abrupt phase changes and develop required features; changes in structural parameters (propagation phase) [25,26] and rotating the principal axis (Pancharatnam-Berry phase/geometric phase) of metaatoms. [27][28][29][30][31] A structural parametric approach can be used to achieve the desired phase profile for linearly polarization. However, it usually faces narrow bandwidth problems due to the inherent dispersion of resonant meta-atoms.…”