Switchable Display Research Articles

On‐Chip‐Driven Multicolor 3D Meta‐Display

AbstractIntegrating metasurfaces on‐chip provides a promising approach to modulating and extracting the in‐plane waves, which bridges the conversion between guided and free‐space waves and suggests tremendous applications, including guided‐wave‐driven holography, photonic integrated lasers, and on‐chip routers. However, despite these efforts, it remains challenging to achieve multicolor 3D holographic projections via on‐chip meta‐optics, along with switchability. Here, the multicolor 3D holography free from zero‐order diffraction and the immersion switchable display enabled by the on‐chip integrated metasurface is proposed and demonstrated. By leveraging the propagation‐accumulated phase of the guided waves and exploiting an optimization algorithm, an on‐chip meta‐hologram driven by guided waves is developed to project both multicolor and multiplane images with independent encoding freedom. Moreover, the switch between two colorful holographic images is also demonstrated via an easily accessible immersion tuning scheme. Such an on‐chip‐driven meta‐hologram exhibits low background noise or crosstalk with high information quality and is also free from sophisticated nanostructure searching or elaborate target‐image predesigning. The proposed on‐chip‐driven metasurface for multicolor 3D holography promises future applications in dynamic display, virtual/augmented reality, and liquid sensing.

Holographic multiplane augmented reality head-up display with switchable display modes based on polymer dispersed liquid crystal.

The multiplane augmented reality (AR) head-up display (HUD) is important in improving driving safety and comfort. In this paper, we propose an AR-HUD with switchable display modes based on polymer dispersed liquid crystal (PDLC) and lens holographic optical elements (HOEs), which can provide two display modes: the dual-virtual-image mode and the virtual-real-image mode. The dual-virtual-image mode can produce two virtual images at different depths, which can provide a better sense of reality integration for the driver to improve driving safety and comfort. The virtual-real-image mode can produce one far virtual image and one near real image at different depths, and it provides a larger eye box (EB) for both driver and passengers in the car and a higher image contrast. The two display modes can be switched by an electronically controlled scattering module consisting of a pair of PDLC films. The proposed AR-HUD system is compact and equipped with multiplane display and mode-switching functions, and is expected to be applied in the future.

Large aperture liquid crystal lens array based on integrated composite electrodes for 2D/3D switchable displays

A large aperture liquid crystal (LC) lens array based on integrated composite electrodes (ICE-LC) lens array with low operating voltages is proposed. The top substrate contains composite electrodes, while the bottom substrate contains strip electrodes. Composite electrodes are further categorized into integral plate electrode (IPE) and rectilinear-patterned electrode (RPE). Meanwhile, the strip electrodes consist of auxiliary electrodes and pixel electrodes. During the focusing mode, the electric field can easily propagate through the LC layer. Simultaneously, the voltage on auxiliary electrodes is maintained lower than that on pixel electrodes to optimize the electric field distribution. To assess the operating efficiency of the ICE-LC, an evaluation of the conventional model is taken during the simulation. Simulation results show that the ICE-LC lens array achieves the shortest focal length at a low operating voltage. The pixel electrodes operate at 4.5 Vrms, and the auxiliary electrodes at 0.9 Vrms. This configuration provides an ideal refractive index profile in a relatively thick LC layer. Additionally, this configuration enables 2D/3D switchable display, outperforming current LC lens array in the equivalent aperture.

Locally Switchable 2D and 3D Displays

AbstractIn a 2D/3D switchable display, the 2D and 3D regions can be defined independently on screen on a per‐pixel, per‐timeframe basis.

Machine learning phase modulation of liquid crystal devices for three-dimensional display.

A machine learning phase modulation scheme based on convolutional neural networks (CNN) and recurrent neural network (RNN) is proposed to carry out the regression task of liquid crystal (LC) device electric field prediction for the 2D/3D switchable display. The hybrid neural network is built and trained based on the illuminance distribution under three-dimensional (3D) display. Compared with manual phase modulation, the modulation method using a hybrid neural network can achieve higher optical efficiency and lower crosstalk in the 3D display. The validity of the proposed method is confirmed through simulations and optical experiments.

Fast response electrically controlled liquid crystal lens array for high resolution 2D/3D switchable display.

A fast response electrically controlled liquid crystal (LC) lens array is revealed. In order to realize the fast response, a double LC layer structure is adopted. The fabricated LC lens array has a small pitch of 310µm and LC layer with a thickness of 50μm. Experimental results show that the focal length of the LC lens array can be continuously adjusted by low driving voltage (∼6.5Vrms), and the shortest focal length is 0.5mm. The switching between 2D display and 3D display is realized by controlling the voltage off and on state of the LC lens array. Experimental result shows that the 2D/3D switchable display has a fast response time of 16ms. The short pitch LC lens array is expected to be used in high-resolution 2D/3D switchable display.

Switchable 2D/3D display based on a liquid crystal lens array and the rotating specimen shooting method.

A liquid crystal (LC) lenticular lens array with auxiliary electrodes is proposed. The introduction of the auxiliary electrodes helps to obtain an LC lens array (LCLA) with relatively large aperture without complex structures. When the LCLA is in the focusing state, the voltage of auxiliary electrodes is less than that of edge electrodes, and the generated electric field in the LCLA can penetrate into the LC layer. Therefore, the ideal phase profile is obtained with a relatively thin LC layer thickness. Experimental results show that the LCLA has the characteristics of high optical power and low operation voltage. Based on the proposed LCLA, a multi-view 2D/3D switchable display is realized. In the experiment, a series of parallax images is obtained by rotating the sample to replace the convergence shooting method for 3D imaging. Compared with other 2D/3D switchable display devices, the multi-view 2D/3D switchable display based on the LCLA is characterized by being thin and compact, and displaying no moiré pattern.

37‐4: Student Paper: Depth‐Enhanced 2D/3D Switchable Display Based on Integral Imaging

The development of two‐dimensional (2D)/three‐dimensional (3D) switchable displays in the display market is limited due to the narrow depth of 3D display mode. In this paper, we propose a depth‐enhanced 2D/3D switchable display based on integral imaging that stacks multiple polarization switching layers and multiple polarization‐dependent liquid crystal micro‐lens arrays (LCMLAs) together. According to the change of the incident polarization state by the polarization switching layer, the polarization‐dependent LCMLA can realize the focusing effect and transmission effect respectively. Because different layers of polarization‐dependent LCMLA have different gaps (g) and the combination of different layers of polarization‐dependent LCMLA obtains different focal lengths (f), hence, multiple central depth planes can be generated to improve the depth of field (DOF) of the 3D mode. The 2D display mode is realized when all the layers of the polarization‐dependent LCMLA are in transmission effect. We experimentally developed a prototype of the proposed 2D/3D switchable display with two polarization switching layers and two polarization‐dependent LCMLAs. The results show that the DOF of the prototype is easily increased by more than two times. At the same time, the 2D image is also clearly presented in 2D mode without any distortion.

Depth-enhanced 2D/3D switchable integral imaging display by using n-layer focusing control units

ABSTRACT Depth of field (DOF) is one of the important parameters of three-dimensional (3D) displays. A two-dimensional (2D)/3D switchable display that can display both high-resolution 2D images and vivid 3D images with large DOF is an ideal purpose. In this paper, we propose a depth-enhanced 2D/3D switchable integral imaging display by using n-layer focusing control units (FCUs). Each layer of FCU is composed of a polarization switch and a polarization-dependent liquid crystal micro-lens array (LCMLA). According to the polarization state of incident light switched by the polarization switch, the polarization-dependent LCMLA can realize focusing effect or transmission effect, respectively. Because each layer of FCU has two optional optical effects and has different gap from the display panel, the combination of n-layer FCUs could generate 2 n -1 central depth planes, hence 2 n -1 sub-DOFs can be obtained for depth-enhanced 3D display. The 2D display mode can be easily realized when all layers of FCUs are transmission effect. We experimentally set up a prototype of the proposed 2D/3D switchable display with two-layer FCUs. The experimental results indicated that the proposed prototype can effectively increase the DOF of 3D display and realize 2D/3D switchable display as well.

Polarization-sensitive switchable display through critical coupling between graphene and a quasi-BIC.

Enhanced light-matter interaction of a local field is of prime importance in optics as it can improve the performance of nanophotonic devices. Such enhancement can be achieved by utilizing the optical bound states in the continuum (BICs). In this study, a dielectric metasurface is proposed that could enhance the light-matter interactions in graphene. A symmetry-protected BIC was observed in such a metasurface, which could transform into a quasi-BIC with a high quality (Q-) factor when the in-plane symmetry is broken. As the graphene monolayer was introduced into the system, its absorption was enhanced by the quasi-BIC resonance. By optimizing the graphene Fermi energy and the asymmetry parameter of the metasurface to satisfy the critical-coupling condition, a tunable absorber could be achieved. The absorbing intensity could be efficiently modulated by varying the polarization direction of the incident light, the maximum difference of which was up to 95.4%. Also, further investigation showed that such a feature indicates potential application in digital switches and image displays, which could be switched by incident polarization only, and therefore without dependence on an additional structural change.

Fast responsive 2D/3D switchable display using a liquid crystal microlens array.

A fast responsive two-dimensional/three-dimensional (2D/3D) switchable display is demonstrated based on an active liquid crystal (LC) microlens array and a twisted nematic (TN) cell. Compared with the traditional LC microlens array, the fabricated LC microlens array has more ideal phase profile and better focusing effect. The TN cell can switch the polarization direction of the incident light with a very short switching time (4.3 ms) and a small driving voltage (5Vrms). By introducing the tilted elemental image arrays and tilted LC lens array, the moiré patterns are eliminated. The fast switching of the 2D/3D display can be realized by applying or removing voltage to the TN cell. The fast responsive 2D/3D switchable display with the LC microlens array and the TN cell is thin and compact without moiré pattern compared with other 2D/3D switchable display devices.

Four-mode 2D/3D switchable display with a 1D/2D convertible liquid crystal lens array.

A four-mode 2D/3D switchable display using a 1D/2D convertible liquid crystal (LC) lens array is proposed in this paper. The LC lens array is composed of two orthogonal LC lens arrays, with a λ/2 film in the middle to rotate the polarization by 90°. Based on the LC lens array, a four-mode 2D/3D switchable display is realized, which is switchable between the turn-off and turn-on states: when the operating voltage V1 = 0, V2 = 0, the display operates in mode I, which is 2D display; when the operating voltage V1 = 0, V2 = 0, the display operates in mode II, and the 3D display effect is in x direction; when the operating voltage V1 = 0, V2 = 0, the display operates in mode III, and the 3D display effect is in y direction; when the operating voltage V1 = 0, V2 = 0, the display operates in mode IV, the 3D display effect is in x-y plane. Experimental results indicate that the LC lens array has simple fabrication process, low operating voltage (∼5.4V), and short focal length. Moreover, based on the designed LC lens array, the 2D/3D switchable display shows no moiré pattern.

Optofluidic lenticular lens array for a 2D/3D switchable display.

In this paper, we propose an optofluidic lenticular lens array (OLLA) for a two-dimensional/three-dimensional (2D/3D) switchable display. The OLLA includes a bottom substrate layer with lenticular lens structure, a microfluidic layer with microchannels, and a top substrate layer with inlets as well as outlets. A micro gap is formed between the lenticular lens of the bottom substrate layer and the top substrate layer. When air is in the micro gap, the OLLA behaves as a lenticular lens array, which can realize 3D display. When fluid is filled in the micro gap, because the refractive index of the fluid is the same with the lenticular lens structure, the OLLA equivalents to a transparent flat panel, which can realize a 2D display. Experiments verify that a switchable 2D/3D display prototype based on this OLLA and a smartphone achieves both high-resolution 2D display and high-quality 3D display.

Multi-View 2D/3D Switchable Display with Cylindrical Liquid Crystal Lens Array

We propose a multi-view 2D/3D switchable display by using cylindrical liquid crystal (LC) lens array with a low operating voltage and fast response time. The cylindrical LC lens array is composed of three parts: the LC layer, a top-plane indium tin oxide (ITO) electrode, and bottom periodic strip ITO electrodes. In the voltage-off state, the cylindrical LC lens array is equivalent to a transparent glass substrate and the viewers can see a clear 2D image. In the 3D mode, the cylindrical LC lens array can be used as a cylindrical lens array under a suitable operating voltage. As a result, the 2D and 3D images can be switched according to the state of the cylindrical LC lens array. The experimental result shows that the 2D/3D switchable display with the cylindrical LC lens array has a wider viewing angle, has no moiré pattern, and is much thinner compared to the other 2D/3D switchable display devices.

Graphene Metapixels for Dynamically Switchable Structural Color.

Structural coloration providing vibrant and tailored colors enables broad applications. Existing strategies of structural coloration either use resonances or diffraction induced by arrayed nanostructures with element sizes at a wavelength scale or are based on interference from vacuum-deposited large-area thin films. It is extremely challenging to achieve full color pixels with diffraction-limited resolution without sophisticated multiple-step nanostructure fabrication or externally applied field control. Realization of dynamically switchable full color displays with diffraction-limited resolution is even harder. This work demonstrates a structural color strategy with developed anisotropic graphene metapixels. The anisotropic optical property is given by the intrinsic birefringence of the layered structure of graphene metamaterials, and each metapixel is spatially encoded by direct laser printing with diffraction-limited resolution (250 nm). The colors can be dynamically and instantly switched by controlling the scattering of the light source to excite different modes based on the strong anisotropic optical properties of the graphene metapixels. The low-cost large-scale fabrication method allows experimental demonstration of a large-area (4 in.) flexible full color optical switchable display. Such a simple, effective and flexible method promises broad practical applications in color display and color image sensing related fields.

Reflective‐Type Transparent/Colored Mirror Switchable Device Using Reversible Electrodeposition with Fabry–Perot Interferometer

AbstractReversible electrodeposition (RED) devices have been considered as the optical transmittance or reflectance switchable display for the reflective display applications. In this study, transparent/colored mirror switchable RED device is demonstrated by integrating the Fabry–Perot (FP) interferometer. Indium‐tin‐oxide (ITO)‐based FP interference effect is utilized for color filter to emit particular wavelength. Color‐switchable RED cells are researched using ITO (red, green, and blue (RGB)) films and tungsten (W) films as partially reflective layers for the cavities. The red/green/blue colored mirrors are developed according to ITO thickness as the Ag film deposit. Then, the ITO (RGB) pixelated RED devices are investigated by differential deposition process. In the 25 × 25 µm2 sized ITO (RGB) micro‐subpixels mirror, the high transparent and high reflectivity states are successfully achieved, which can be applied to reflective‐type transparent displays.

Electrically high-resistance liquid crystal micro-lens arrays with high performances for integral imaging 3D display

In this paper, we propose a high-resistance (Hi-R) liquid crystal (LC) micro-lens arrays (MLAs) with a low operating voltage and a controllable focal length for integral imaging (II) 3D display. The focal lengths of the Hi-R LC MLAs can be effectively controlled by applying different operating voltages and driving frequencies. The experimental results indicate that the focal lengths can be adjusted from 4.27 mm to 2.88 mm when the operating voltage applied to the Hi-R LC MLAs increases from 1.8 Vrms to 2.8 Vrms at the driving frequency of 130 kHz. Compared with the II 3D display by using ITO circular-hole electrodes-based or Al circular-hole electrodes-based LC MLAs without Hi-R layer, the II 3D display based on the Hi-R LC MLAs with Al circular-hole electrodes can reveal clear 3D scenes at the corresponding center depth plane (CDP) when a low operating voltage is applied to the Hi-R LC MLAs. Furthermore, the generated elemental images with different depths can be reconstructed at different CDPs by electrically controllable focal lengths of the Hi-R LC MLAs, and these 3D scenes can be realized the switchable display in the same II 3D display system, which can effectively present the optical performance of the II 3D display.

Chemical Modification of the Yeast Cell Surface Allows the Switch Between Display and Soluble Secretion of Full-Length Antibodies.

The classical yeast surface display (YSD)-based antibody hit discovery relies on the enrichment of candidates from large antibody fragment libraries by fluorescence-activated cell sorting (FACS), followed by sequencing of the remaining diversity. The sequences of hit candidates are then transferred into plasmids, which allow their expression as full-length IgG in mammalian cells. After production and downstream processing, antibodies are further qualified in biochemical and functional assays. This multistep process has been proven to be successful in academia and has also found its way to the biopharmaceutical industry. However, during the recent decade, several groups tried to simplify this process by enabling either switchable or simultaneous secretion and display of antibodies or antibody fragments by yeast cells. Therefore, functional testing of candidates can be accomplished immediately during the screening process, while eliminating the need for tedious sequence reformatting and production host change. In this protocol, we give guidance for the establishment of a full-length antibody display system on yeast cells, which permits a simple switch to soluble antibody secretion.

Tilted LCD Pixel With Liquid Crystal GRIN Lens for Two-Dimensional/Three-Dimensional Switchable Display

In this paper, high images quality switchable two-dimensional (2-D)/3-D display is achieved by carefully matching the high-resolution liquid crystal display (LCD) pixel structure and liquid crystal graded index (GRIN) lens. A parallelogram LCD pixel structure is proposed, in which the edges of each sub-pixels are slanted. At the top of the LCD pixels, the liquid crystal GRIN lens is also tilted to reduce the moire effect and the tilt angle is carefully aligned with the edges of subpixels of LCD. This accurate alignment is useful to eliminate the crosstalk and improves the imaging quality of 3-D display. The 2-D/3-D switchable display is realized by tuning the liquid crystal in the GRIN lens. Based on this, a 3-D display based on 32-inch 8K4K resolution LCD display and Liquid crystal GRIN lens was designed.

35‐2: 3D/2D Switchable Display System Based on Integral Imaging

A 3D/2D switchable display system based on integral imaging is proposed by using a projection screen and a projector. The projection screen consists of a lens array holographic optical element (LAHOE) and a polymer dispersed liquid crystal (PDLC) film. The experimental results prove the feasibility of the proposed system.