Hitachi developed 200GB holographic disk

Hitachi said it will begin sampling a holographic disk with a 200GB capacity in Fall 2005.

The 5-inch (130 mm) disk has a holographic system that writes and reads data with a blue laser. The laser beam splits into two beams, a signal beam that convey data and a reference beam. Data to be stored is encoded into data pages, which are written in multiplex in the storage media.

Read more at Storage Pipeline