Takahiro Tanino

Relationship between molecular structure and photoinduced surface relief grating formation using azobenzene-based photochromic amorphous molecular materials

The relationship between molecular structure and photoinduced surface relief grating (SRG) formation has been investigated by using azobenzene-based photochromic amorphous molecular materials. It was shown that modulation depth of SRG formed by irradiation with two coherent Ar+ laser beams (488 nm) becomes larger with increasing glass-transition temperature of the material. However, introduction of bulky substituents at both phenyl groups of the azobenzene moiety was undesirable for photoinduced SRG formation. These results were discussed from the viewpoints of frequency of trans–cis and cis–trans isomerization cycles and fluidity of the material upon irradiation.

Surface relief grating formation on a single crystal of 4-(dimethylamino)azobenzene

Surface relief grating (SRG) formation on an organic single crystal by irradiation with two coherent laser beams has been demonstrated by using 4-(dimethylamino)azobenzene (DAAB). It was found that the SRG formation was greatly depending upon both the coordination of the crystal and the polarization of the writing beams. The dependence of the polarization of writing beams on the SRG formation using the single crystal was found to be quite different from that reported for amorphous polymers and photochromic amorphous molecular materials, suggesting that the mechanism of the SRG formation on the organic crystal is somewhat different from that on amorphous materials.

Creation of azobenzene-based photochromic amorphous molecular materials—synthesis, glass-forming properties, and photochromic response

A novel family of azobenzene-based photochromic amorphous molecular materials has been created. They were found to readily form amorphous glasses with well-defined glass-transition temperatures and to exhibit photochromism as amorphous films as well as in solution. It was found that their quantum yields of trans–cis photoisomerization were smaller as amorphous films than in solution and that the backward cis–trans thermal isomerization reactions as amorphous films were either accelerated or retarded relative to those in solution, depending upon their molecular structures. In addition, the rate acceleration for the cis–trans thermal isomerization as amorphous films relative to solution was found to be more prominent as the irradiation time for generating the cis-isomer became shorter.

Surface Relief Grating Formation Using a Novel Azobenzene-based Photochromic Amorphous Molecular Material, Tris[4-(phenylazo)phenyl]amine

ABSTRACT A novel azobenzene-based photochromic amorphous molecular material, tris[4-(phenylazo)phenyl]amine (TPAPA), was designed and synthesized. TPAPA was found to readily form an amorphous glass with a glass-transition temperature of 67°C and to exhibit photochromism as amorphous film. Irradiation of amorphous film of TPAPA with two coherent Ar+ laser beams led to the formation of surface relief grating with a diffraction efficiency of 2 ≈ 3% and a modulation depth of ca. 100 nm.

Photochromic Amorphous Molecular Material: Polarized-Light Induced Dichroism of Amorphous Film of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]azobenzene

ABSTRACT Dichroism of amorphous film of an azobenzene-based photochromic amorphous molecular material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene (BFlAB), induced by irradiation with linearly polarized Ar+ laser light has been investigated.

Fabrication and evaluation of all-optical 1×2 Y-branch waveguide switch using photochromic amorphous molecular materials

Photochromic dye is expected for all-optical waveguide switches because it could change its refractive index by UV or visible light irradiation. One of photochromic amorphous molecular materials, 4-[bis(9,9-dimethylfluorene-2-yl)amino] azobenzene (BFlAB) readily formed stable amorphous glasses above room temperature without polymer dilution and it showed large refractive index change and good processability. We fabricated an all-optical 1 × 2 Y-branch waveguide switch by simple process and evaluated its optical properties and switching function.