Abstract

An attractive feature of holographic optics is the possibility of achieving high-density optical storage by writing digital information in the form of micro-holograms recorded in the volume of a suitable photosensitive substrate. This approach can considerably improve the volume capacity, storage density and response time of the next generation optical data-storage systems. In this framework the European Microholas project aims at developing a new class of DVD-like optical memories. In particular, the project aims at a huge increase of the disk capacity, by recording periodic nanostructures (reflection micro-holograms) in the disk volume (Holographic DVD), rather than "digging pits" on the disk surface as in conventional CDs/DVDs. The main advantage of this approach is that it gives to the bit-oriented storage the third dimension: using highly focused beams, it is possible to record multiple tracks at different depth in the disk volume. In addition, wavelength multiplexing allows a linear increase of the data density and also of the write/read rate with the number of wavelength used. The performances of a optical data storage system are closely determined by the characteristics of the recording media. The new class of holographic materials [1] should satisfy some important requirements: sensitiveness to blue light, low losses, high resolution and sensitivity, long term stability.

© 2007 IEEE