High-Density Optical Memory and Ultrafine Photofabrication

Abstract

Optical recording uses focused or minimal size laser light to effect some optical property change in recording media, which is subsequently read back by the laser. Various approaches have been proposed to increase the recording density of optical memories: decreasing the recording mark size by using short-wavelength lasers, three-dimensional recordings, and near-field optical recording. Among them the most promising approach is a near-field optical recording. Recording density in conventional optical recording is limited by the diffractive limit of light and the numerical aperture of the lens. Therefore, the mark size cannot be reduced to less than the wavelength of light. In near-field optical recording, in contrast, the size depends only on the diameter of the probe tip aperture. Therefore, the recording density can be increased at will, in principle, if a small aperture tip is available.