Development of New Thin Film Multilayered Systems for Recordable Optical Disc Memory Compatible with CD and DVD

Archival data on the CD-R, which has been explosively popularized in the past five years, cannot be read with DVD-ROM drives or upcoming Blu-ray disc drives if these drives are equipped with a single laser of 650 nm or 405 nm in wavelength. To overcome this inconvenience inevitable in the near future, we developed a new class of recordable opt ica l d isc memories in collaborat ion with DENSO Corporation. The research activities reviewed here involve (1) proposal of a new recording mechanism, (2) observation of transient phenomena in the new recording mechanism, (3) materials design of thin-film multilayered systems, (4) optimal pre-groove design of optical disc substrates, whose details are described in the research reports in this special issue. The newly developed recordable opt ical discs were compatible with the conventional CD-R and could be also played with DVD-ROM drives, unlike conventional CD-R. Taking advantage of this first realization of DVD-compatibility, the new medium has already been used in software development for car navigation systems via builtin DVD-ROM drives. This "future compatibility", being an essential requisite for archival purposes, should see numerous applications of various types and shapes.