Precise control over molecular movement is of fundamental and practical importance in physics, biology, and chemistry. At nanoscale, the peculiar functioning principles and the synthesis of individual molecular actuators and machines has been the subject of intense investigations and debates over the past 60 years. In this review, we focus on the design of collective motions that are achieved by integrating, in space and time, several or many of these individual mechanical units together. In particular, we provide an in-depth look at the intermolecular couplings used to physically connect a number of artificial mechanically active molecular units such as photochromic molecular switches, nanomachines based on mechanical bonds, molecular rotors, and light-powered rotary motors. We highlight the various functioning principles that can lead to their collective motion at various length scales. We also emphasize how their synchronized, or desynchronized, mechanical behavior can lead to emerging functional properties and to their implementation into new active devices and materials.

Design of Collective Motions from Synthetic Molecular Switches, Rotors, and Motors

An optical interference color display comprising a transparent substrate, an inner-front optical diffusion layer, a plurality of first electrodes, a patterned support layer, a plurality of optical films and a plurality of second electrodes is provided. The inner-front optical diffusion layer is on the transparent substrate and the first electrodes are on the inner-front optical diffusion layer. The patterned support layer is on the inner-front optical diffusion layer between the first electrodes. The optical film is on the first electrodes and the second electrodes are positioned over the respective first electrodes. The second electrodes are supported through the patterned support layer. Furthermore, there is an air gap between the second electrodes and their respective first electrodes.

Optical interference type of color display

The design and preparation of azobenzene-containing polymers showing a large photoinduced change in refractive index, and their applications to rewritable Raman-Nath and Bragg holograms are reviewed. Holographic performance has been remarkably improved with regard to diffraction efficiency, response time and multiplicity by development of newly designed polymer systems.

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Rewritable holograms based on azobenzene-containing liquid-crystalline polymers

Polymer Blends with Azobenzene‐ Containing Block Copolymers as Stable Rewritable Volume Holographic Media

Volume holographic data storage is one of the most promising techniques to improve both the storage capacity of devices and the transfer data rate. Among the materials proposed as storage data media, azobenzene containing polymers have received much attention. Some of their properties seem to be suitable for holographic storage applications. However, they still present several problems, mainly those related with light sensitivity, response time and stability of the stored information. In this article we review the work performed on volume holographic storage using azobenzene containing polymers as well as the different approaches that have been proposed to overcome those problems.

The volume holographic optical storage potential in azobenzene containing polymers

A hologram recording method for recording information of signal light as holograms in an optical recording medium, which includes illuminating signal light at the optical recording medium; illuminating reference light at the optical recording medium simultaneously with the signal light such that an interference pattern is formed by the signal light and the reference light intersecting in the optical recording medium; and shifting a region in the optical recording medium at which the signal light and the reference light intersect, by shifting an illumination position of the reference light along an optical axis of the signal light, thereby recording a plurality of holograms in the recording medium.

Hologram recording method and hologram recording device

Laser light output from a laser light source is irradiated onto a transmission-type scale. Due to movement of the transmission-type scale, a polarization angle of transmitted light varies in accordance with variations in orientations of half-wave plates arrayed in a longitudinal direction. It is difficult for the polarization angle to be affected by noise factors such as external light or the like. Light intensity of a polarized light component, which is transmitted through an analyzer and detected at a photo-detector, varies in accordance with the polarization angle. Thus, the light intensity varies as the transmission-type scale moves, and a detection signal is output to a movement amount computing device. When an amount of movement is computed on the basis of the signal, the exact amount of movement can be detected.

Optical encoder and scale for encoder

An optical recording/reproducing apparatus having excellent resistance against vibration and noise is provided. In recording, coherent light is polarization-modulated with a spatial light modulator to generate signal light and reference light whose polarization directions are crossed at right angles with each other. The signal light permeates a polarizing beam splitter, and is incident to a quarter wavelength plate. The reference light passes through a passing hole, is diffused by a light diffuser and is incident to the quarter wavelength plate. The reference and signal light are converted into circularly polarized light which revolve in directions opposite to each other and condensed by a condenser lens, and then a predetermined area of an optical recording medium is irradiated with the reference and signal light. Thus, the reference and signal light are generated by modulating the incident light from the same light source and are coaxially incident to the polarizing beam splitter.

Optical recording apparatus and optical recording/reproducing apparatus

Diffraction efficiencies of holograms in thick azo polymer films were improved by designing optical densities of the films. A nonphotosensitive polymer was used as a binder for controlling the dye concentrations. We fabricated 250-µm-thick films by changing the concentrations. While the optically induced birefringence decreased with decreasing concentration, reduction of absorption loss of the reading beam increased the diffraction efficiency. Thus, owing to the competition between the decrease in birefringence and the increase in efficiency, there exist appropriate concentrations for improving both sensitivity and magnitude of the diffraction efficiency. Consequently, the diffraction efficiency reached 25% without degradation of the sensitivity. We also demonstrated holographic multiplexing using the film. A set of 20 data pages (66 kbits per page) was successfully multiplexed and retrieved with a low bit-error rate of 1.3×10-3. The use of an error correction coding would allow error-free recovery of the data pages.

http://iopscience.iop.org/article/10.1143/JJAP.43.4964/pdf

Design of Dye Concentrations in Azobenzene-Containing Polymer films for Volume Holographic Storage

A hologram recording method includes generating a signal beam with data formed by superimposing pattern data, the pattern data representing a pattern in which a large number of plural kinds of pixels having different tone values are arranged in a two-dimensional manner, on an image data of respective pixels represented by tone values corresponding to density, and recording a hologram by irradiating a converted beam formed by Fourier transformation of the generated signal beam with a lens and a reference beam to an optical recording medium.

Shin Yasuda

Papers

Hologram recording method and hologram recording device

Optical encoder and scale for encoder

Optical recording apparatus and optical recording/reproducing apparatus

Design of Dye Concentrations in Azobenzene-Containing Polymer films for Volume Holographic Storage

Hologram recording method and hologram recording apparatus