Abstract: A three-dimensional fractal-structure body partially or entirely comprises a three-dimensional fractal structure, the fractal structure body having a local minimum value at a particular wavelength determined by structural and material factors of the fractal structure in a transmissivity for electromagnetic waves and/or a local minimum value at a particular wavelength determined by structural and material factors of the fractal structure in the reflectivity for electromagnetic waves.

Abstract: A three-dimensional fractal structure body that had not been realized by the prior art and newly developed technologies is provided. The fractal structure body partially or entirely comprises a three-dimensional fractal structure, the fractal structure body having a local minimum value at a particular wavelength determined by structural and material factors of the fractal structure in a transmissivity for electromagnetic wave and/or a local minimum value at a particular wavelength determined by structural and material factors of the fractal structure in the reflectivity for electromagnetic wave.

Abstract: A material for optical recording by utilizing the photochemical hole burning is disclosed. The optical recording material is a composition comprising a watersoluble deuterated polymer as a host component and a water-soluble organic pigment dispersed in the host component as a guest component. By virtue of the deuteration of the host component, the tunnel effect of the hydrogen atoms in the host component is prevented, so that the hole width is narrowed. Thus, the wavelength multiplicity is increased.

Abstract: Disclosed is an optical recording material comprising a porphine derivative having at least an ionic group and a polymer compatible with this porphine derivative. As the porphine derivative, there are used a porphine derivative having an N-alkylpyridinium group, such as 5,10,5,20-tetra(4-N-methylpyridinium) porphine, a porphine derivative having a quaternary amino group, such as 5,10,15,20-tetra(4-N,N,N-trimethylaminophenyl) porphine, a porphine derivative having a sulfonatophenyl group, such as 5,10,15,20-tetra (4-sulfonatophenyl) porphine, and a porphine derivative having a carbonatophenyl group, such as 5,10,15,20-tetra-(4-carbonatophenyl) porphine. Either an organic polymer or an inorganic polymer is used as the polymer. From the viewpoint of the recording stability, a water-soluble polymer such as polyvinyl alcohol or sodium polystyrene sulfonate is preferred as the organic polymer.