Opticaily-induced phase change
Although the principle of the optically-induced reversible
phase change was demonstrated by Ovshinsky’s group [6]
about a quarter of a century ago, optical memory systems
utilizing the phenomenon were not commercialized until
very recentty. The principle seems to be simple but the
development of semiconductor lasers, which are compact
and intense light sources, were necessary as a prerequisite
for commercialization purposes.