Takeo Sasaki

By Takeo Sasaki

Part of the book: Ferroelectrics

By Takeo Sasaki

Part of the book: Advances in Ferroelectrics

By Takeo Sasaki

In this chapter, the photorefractive effect in photoconductive ferroelectric liquid crystal blends is described. A blend of liquid crystals that form chiral smectic C phase and photoconductive compounds shows the photorefractive effect. The ferroelectric liquid crystal blends containing a photoconductive chiral compound were found to exhibit a gain coefficient of over 1200 cm-1 and the response time of sub-millisecond. Using the blend, real-time dynamic amplification of an optical image signal of over 30 fps was demonstrated.

Part of the book: Ferroelectric Materials

By Takeo Sasaki, Khoa Van Le and Yumiko Naka

In this chapter, we introduce poly(olefin sulfone)s and review the recent progress on the photoinduced depolymerization of poly(olefin sulfone)s as well as their applications. Poly(olefin sulfone)s combined with photobase generators (PBGs) are depolymerized upon irradiation with light. A poly(olefin sulfone) is a 1:1 alternating copolymer of olefin monomer and sulfur dioxide in which the protons on the carbons adjacent to the sulfonyl groups can be readily abstracted by a base. This removal leads to a depolymerization chain reaction, resulting in incorporation of a photobase generating chromophore that can undergo a photoinduced unzipping reaction. During this reaction, the original olefin monomer and sulfur dioxide are regenerated from the primary chain of the poly(olefin sulfone). The photoinduced depolymerization of poly(olefin sulfone)s has been investigated for a wide variety of applications, including stereolithography, printable microcircuit fabrication, and removable adhesives.

Part of the book: Alkenes

By Takeo Sasaki, Khoa Van Le, Yumiko Naka and Takafumi Sassa

This chapter summarizes the state of the art of research regarding photorefractive liquid crystals. Photorefractive effect is of interest because it can be used to obtain dynamic holograms, based on interference between dual laser beams within a liquid crystal to generate a refractive index grating. This technique can be employed in numerous diffraction optics applications, such as optical amplifiers, phase-conjugate wave generators, 3D displays, novelty filters, and optical tomography. The photorefractive effect in liquid crystals is especially pronounced, and both ferroelectric and nematic liquid crystals have been researched for this purpose, with the former showing special promise in practical applications. As an example, ferroelectric liquid crystals have been found to readily produce a refractive index grating in conjunction with a significant gain and a formation time of 900 ms.

Part of the book: Liquid Crystals