Outline of Research

RISU_TOP.GIF - 4,722BYTES

RESEARCH_IMAGE.GIF - 15,497BYTES

Keywords of our research:
liquid crystal, polymer, dye, hologram、grating, polarization, photorefractive, optical information processing, nonlinear optics, optical device, polymer dispersed liquid crystal, liquid crystal composite, Fourier optics, optical recording, optical material, polymer liquid crystal, photopolymer

We concentrate on the study of "photo-control of molecules" and try to apply the opto-eletronics systems including holographic data storage, optical information processing, highly-functionalized optical devices, and display devices.

Polarization gratings using photo-cross-linkable polymer liquid crystals

The alignment directions of mesogenic molecules in photo-cross-linkable polymer liquid crystals can be controlled by both polarization states and exposure energy. The thermally stable orientational patters are fabricated by means of polarization holographic technique. The resulting polarization gratings can diffract the laser beam and controll the polarization states at the same time. The thermally stable polarization gratings should be applied to the highly-functionlized optical devices used in the opto-electronics systems such as optical information processing, optical recording and display devices.

Orientational photorefractive effects in liquid crystals

The photorefractive effects in the liquid crystals originate in the space charge field and resuting reorientation of the mesogeic molecules. We have presented the two novel classes of photorefractive mesogenic systems; 1) polymer dissolved liquid crystal composite (PDLCC) and 2) photorefractive liquid crystal cell with hybrid-layered structure. These photorefractive mesogenic systems are expected to be applied in the field of real-time holography and high-density optical memory systems.

Nonlinear optics in liquid crystals
Huge optical nonlinearity has been observed in liquid crystals. The large optical nonlinearity in liquid crystals causes the interesting phenomena such as multi-beam mixing (two-wave mixing, degenerate four wave mixing, etc.) and self-phase modulation. The nonlinear optics in liquid crystals is expected to be applied to future all-optical information processing.

Liquid crystal gratings
The liquid crystal cell with periodically-modulated alignment layers provides the eletrically-active optical gratings. In our laboratory, the liquid crystal grating has been fabricated by using the photo-aligned polymer liquid crystals as periodically-modulated alignment layers and the optical properties have been simulated by means of Jones matirx method.

Polarization-multiplex recordings

If the each digital data can be multiplex-recorded by using the recording beams with different polatization states, the density of the optical recording can be improved without changing the core technology of the present optical disk. The polarization mutiplex recording has been presented by using the highly-functionalized photocrosslinkable polymer liquid crystals.

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