Near-field optics: a new tool for data storage

Evanescent energy can be used to produce extremely small optical spots. Two practical implementations that use evanescent energy are aperture probes and solid immersion lenses (SILs). For data storage, the optical near field is defined in terms of evanescent coupling between the system used to read data and the recording layer. Because of the small spot size, near-field techniques are applied to optical data storage systems in order to increase recording density. Both aperture-type systems and SIL systems show good promise of achieving densities of more than 150 Gb/in/sup 2/. The characteristics and performance of several systems are compared, and future near-field technologies are discussed.