Advanced optical and magneto-optical recording techniques: a review

Abstract

Optical data storage is advancing rapidly as we move forward in the 21st Century. Most people today are familiar with CDR and CD-RW as forms of optical data storage, but DVD-R, with considerably higher capacity, will challenge CD-R as the preferred storage medium soon. This review paper looks at the current state of optical recording and some of the current techniques which offer increased magneto-optical storage density, such as Magnetic Super Resolution (MSR), which is already on the market as the GIGAMO disk, and other methods under development. The latter includes Magnetically AMplified Magneto-Optical System (MAMMOS) and Domain Wall Displacement Detection (DWDD). To complement these technologies are a variety of optical techniques, such as near-field recording, which will enable higher storage densities by overcoming the diffraction limit. Holographic storage has promised much over the years, and has largely remained in the research domain. However, new materials and multiplexing techniques show considerable promise for this volumetric storage medium. The overlapping optical and magneto-optical technologies have yielded the concept of hybrid recording and this will also be addressed in this paper. The paper concludes with a look at alternative storage mechanisms, which utilise electronic, as opposed to thermal transitions, to offer improved data rates and improved storage efficiency, and this may dramatically change the way data is stored.