Patent ID: 7656777
Filing Date: 2010-02-02
Classification: G11B

Abstract:
1. A multilayer optical recording medium including a plurality of recording layers for recording/reproducing information by irradiation with light having a wavelength λ0, wherein at least one of the plurality of recording layers includes a variable absorption film, the variable absorption film includes a material in which electron energy has a band structure and an absorption edge of an absorption spectrum moves toward a long wavelength side in accordance with a rise in temperature by light absorption caused by interband transition of an electron, the material includes as a main component at least one selected from the group consisting of Bi the variable absorption film has a first absorptance with respect to the light having the wavelength λ0 when the variable absorption film has a first temperature, and has a second absorptance higher than the first absorptance with respect to the light having the wavelength λ0 when the variable absorption film has a second temperature higher than the first temperature, the material of the variable absorption film changes in optical characteristics so as to change from an unrecorded state to a recorded state at a predetermined temperature, and a recording mark is formed in a portion of the variable absorption film where the predetermined temperature has been reached, so that information is recorded in said portion of the variable absorption film.