Optical data storage offers the potential advantages of high storage d
ensities, fewer mechanical problems, low reading and writing energies,
ruggedness, and higher data rates. Currently, the only true photonic
optical storage medium is the spectral hole burning scheme. The featur
es of the technique are presented, the materials (e.g. see figure) and
necessary laser technology presented, and a view is given of the pros
pects and requirements for future commercial development.