Holographic Read-Only-Memory System for High-Speed Replication

A novel high-capacity holographic read-only-memory (ROM) disc system is proposed that stores multiple disc-sized data patterns as multiplexed holograms within a single holographic disc using a conical reference beam for rotational symmetry during recording, with continuous serial readout during playback. Estimates predict user-data capacities of 100 GB or more in a 12 cm disc, with replication speeds of a minute or less, using current holographic media parameters and high-power lasers. A method for fabricating transmissive metallic disc-sized data masks is developed and confirmed experimentally for features down to 0.4 µm, through a variation of the optical disc mastering process. The retrieval of raw holographic eye-patterns at a rotation speed of 1000 rpm without the use of servos is demonstrated for linear densities of 0.67 µm per channel bit with EFMPlus channel coding.