The development of digital holography is anticipated for the viewing of 3D images by reconstructing both the amplitude and phase information of the object. Compared to analog holograms written by a laser interference, digital hologram technology has the potential to realize a moving 3D image using a spatial light modulator. However, to ensure a high-resolution 3D image with a large viewing angle, the hologram panel requires a near-wavelength scale pixel pitch with a sufficient large numbers of pixels. In this manuscript, we demonstrate a digital hologram panel based on a chalcogenide phase-change material (PCM) which has a pixel pitch of 1 μm and a panel size of 1.6 × 1.6 cm2. A thin film of PCM encapsulated by dielectric layers can be used for the hologram panel by means of excimer laser lithography. By tuning the thicknesses of upper and lower dielectric layers, a color-selective diffraction panel is demonstrated since a thin film resonance caused by dielectric can affect to the absorption and diffraction spectrum of the proposed hologram panel. We also show reflection color of a small active region (1 μm × 4 μm) made by ultra-thin PCM layer can be electrically changed.

Broadband‐operating active devices within a small‐footprint are highly on demand in various nanophotonic fields such as fiber‐optic communication systems and chip‐based integrated optical circuits. As pioneering approaches, diverse platforms of active metasurfaces (AMs) have been proposed due to their superior tunable functionality and ultra‐compact size. However, most of previous researches provide only limited operating bandwidth because they generally rely on resonant light–matter interaction between active material and plasmonic antenna. In this study, an active wavefront switching metasurface that can operate over 500 nm bandwidth at near‐infrared spectral bands is experimentally realized by utilizing nonresonant U‐shaped Ge2Sb2Te5 nanoantennas. Two different sizes of the U‐shaped antenna are designed to exhibit large transmittance contrast and their optical phases are determined by imposing the orientation angle variation. As an example of the functionality, anomalous refraction angle switching and dispersionless active hologram are demonstrated. The devices provide high signal‐to‐noise ratio (>7 dB) for overall operation bandwidth. It is believed that the proposed AMs can be an innovative platform for real device application thanks to their not only broadband and low‐noise operation but also fast speed, low power consumption switching within a small‐footprint.

A method is proposed for the construction of a square pixel complex spatial light modulator (SLM) from a commercial oblong full-high-definition (full-HD) amplitude SLM using an anamorphic optical filter. In the proposed scheme, one half-band of the optical Fourier transform of the amplitude-only spatial light field is rejected in the optical Fourier plane and the other half-band is reformatted to be an effective complex SLM with square pixels. This has an advantage in the viewing window plane since the shape of the viewing window becomes square and more ideal for observers who watch the hologram contents through it. For optimal transformation, the amplitude computer generated hologram encoding scheme was developed. Mathematical modeling of the proposed system is described herein, and it was experimentally demonstrated that the effective complex SLM displays complex holographic three-dimensional images with a clear depth discrimination effect.

-High-performance 2-μm-channel oxide thin-film transistors (TFT) on glass substrate for a 7-μ m-pixel-pitch spatial light modulator panel for digital holography applications were fabricated using a two-step source/drain etching process. It showed a μ FE of 45.5 cm 2 /Vs, SS of 0.10 V/dec, and Von of near zero voltage. Furthermore, we succeeded in the demonstration of sub-micron TFTs, which is an indispensable route to next-generation spatial light modulation devices with near 1-μm pixel pitch. The issue of short-channel transistors for display applications is also introduced. Finally, the digital holographic demonstration results based on the fabricated backplane are presented.Keywords -sub-micron TFT, spatial light modulator on glass (SLMoG), stitch, mix and match, wet treatment, digital hologram.DOI # 10.1002/jsid.535 Objective and backgroundThe concept of holography was introduced by Dennis Gabor, a Hungarian engineer, during the work on electron microscopes in 1947. 1,2 He used a filtered mercury arc light source, while first holography application was realized after the invention of the laser in 1964. 3 The word "holography" means "whole recording." Holography literally realizes 3D images through the reconstruction of all data from a diffraction pattern on the basis of mathematical calculation and processing. For the public, the main concerns regarding holograms are the resolution and viewing angle of the holographic image. As a consequence of the remarkable development of the display industry over the decades, people are used to high-resolution display. They take the realization of high-resolution holography with natural images for granted. They also want to watch holographic images from various directions freely, as they watch television. For these reasons, when we make a holographic image, two main factors are important: viewing angle and resolution. The relationship between the viewing angle of a digital holographic panel, Ψ , wavelength of laser, λ, and pixel pitch of the panel, p, is given by the following equation.The analog hologram, which is a well-known type of hologram, has met the expectations. It adopts around 10-nm-sized grains (a very fine pixel pitch) on a plate; as a result, people can experience a very natural 3D image and very wide-viewing angle. However, the analog hologram has some constraints. First, the fabrication process for defining very fine pitch through a large area is very hard and expensive. Furthermore, an analog hologram can show only a static holographic image already defined during the fabrication process. For these reasons, industries are trying to realize digital holograms that generally have an active matrix for dynamic video applications. In comparison with the analog hologram, the digital hologram has a relatively large pixel pitch because both the switching transistor and the storage capacitor for dynamic operation should be included in a pixel.Recently, with a focus on achieving a wide viewing angle for the display, many industries have tried to shrink the p...

We propose rewritable full-color computer-generated holograms (CGHs) based on color-selective diffraction using the diffractive optical component with the resonant characteristic. The structure includes an ultrathin layer of phase-change material Ge2Sb2Te5 (GST) on which a spatial binary pattern of amorphous and crystalline states can be recorded. The CGH patterns can be easily erased and rewritten by the pulsed ultraviolet laser writing technique owing to the thermally reconfigurable characteristic of GST. We experimentally demonstrate that the fabricated CGH, having a fine pixel pitch of 2 μm and a size of 32.8 × 32.8 mm2, reconstructs the three-dimensional holographic images. In addition, the feasibility of the rewritable property is verified by erasing and rewriting part of the CGH.