Research activities on materials for wavelength-multiplexed optical recording in Japan

We describe recent research activities on materials for future wavelength-multiplexed optical recording systems in Japan. Organic materials are the major objectives in this field: photochromic materials and the young field of possible photochemical hole burning materials. As for the latter, we introduce our results on organic dye molecules in polymer systems and discuss matrix effects on hole spectrum and the possibility of matrix designing. For the former, recent progress in new materials for erasable and/or multiplexed memory and the relationship of the matrix, performed in universities, governmental laboratories, or industries, is reviewed briefly.