Optical recording medium having first and second super-resolution layers

Abstract

The present invention provides an optical recording medium in which the spot size of incident laser beam, focused on the medium by a far-field optic system characterized by λ and NA, is further reduced and maintained below the diffraction-limited size by means of material characteristics of the medium while reproducing from and recording on the information layer of the recording medium, thus making it possible to record and reproduce a high density of information exceeding the resolution limit of the optic system. A high density optical recording medium according to the present invention adopts a combination of two different super-resolution layers of mutually complementary optical characteristics with increasing light power. The combination of two super-resolution layers is made in either of two different types: for one type, each of the two super-resolution layers, having a respective threshold light intensity (or temperature) for the onset of change in optical transmittance, produces an increasing spot size of the transmitted beam with increasing light power once a respective threshold light intensity (or temperature) is exceeded, and for the other type, one layer produces an increasing spot size of the transmitted beam with increasing light power whereas the other layer exhibits a reverse trend.