Takashi FUKUDA

Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan

(Received September 29, 2004; Accepted January 20, 2005)

An optical recording method was proposed by means of a multiple-code inscription on photo-responsible polymer as a photo-induced surface relief (PSR). The inscribed PSR patterns are erasable and re-writable. The multiple-coding method is based on the combination of angular- and depth-gradations. Expected numbers of the information code recorded on one pit are (n+1)^m, here m and n are angular- and depth-multiplicity, respectively. Therefore, the recording density is expected to be increased exponentially along with the increase of the angular- and depth-multiplicity. For the first attempt, it was confirmed that a recording pit 100 μm square with the multiplicity of m=6 and n=4 could be recorded and read out. This result indicates that the recording density of 1 GB/inch² was achieved.

Key words: re-writable optical recording method, multiple-code inscription, angular-gradation, depth-gradation, photo-induced surface relief formation, azobenzene polymer, high-density data storage