Superdense optical storage

The CD-ROM has made optical storage a common computing resource. Soon, though, other optical technologies will be cramming even more data into still less space. Four technologies (high-density rewritable disks, optical tape, volume holographic storage and electron trapping) could far exceed today´s storage capabilities. Nor are these technologies just research efforts in university or corporate laboratories; the focus is now on developing actual products, and small companies have already formed to do so. Here, the authors examine: what is the technology´s current status; what are the challenges to its realization; and what are its chances for commercial success?