Abstract: The information recording medium comprises a substrate provided with a prepit area and a pregroove area, a dye layer on the substrate and a reflecting layer on the dye layer, wherein the dye layer is a continuous layer formed on both the prepit area and the pregroove area, and the prepit area has a high modulation degree not less than 50%. Its embodiments are as follows: A medium in which a difference between an optical thickness of the dye layer on the bottom portion of a pregroove or a prepit and that of the dye layer on the land portion or a portion between prepits is not more than .lambda./8; one in which a prepit has a half width of 0.2 to 1.4 .mu.m and a depth of 150 to 400 nm, the pregroove has a half width of 0.2 to 1.4 .mu.m and a depth of 70 to 200 nm, the depth of the prepit is larger than the depth of the pregroove by not less than .lambda.

Abstract: A method of optically recording information on an information recording medium comprising a disc-shaped substrate having a pregroove comprising a groove having a depth of 800 to 2,000 angstroms and a half width of 0.2 to 0.7 .mu.m thereon, a recording layer comprising a dye for optically recording information by means of a laser beam which is provided on the substrate, and a reflecting layer of a metal which is provided on the recording layer is disclosed. The recording method is carried out by irradiating a bottom part of the pregroove having the recording layer thereon with a laser beam from the substrate side under rotation of the recording medium. Further, an information recorded medium which is recorded with information by the above method is also disclosed.

Abstract: A method of optically writing an information over an information recorded on a recording material which is reversively convertible between a stable phase and a metastable phase to show different light reflection or transmission by controlling a heating condition to be applied to the recording material wherein the recorded information is recorded in the form of a plurality of separated metastable-phase areas on a stable-phase area is disclosed.

Abstract: A method of recording information comprising the steps of: irradiating a light-absorbing material (which is arranged in contact with a polymer blend which changes in its phase condition between a homogeneous state and a phase-separated state in response to change of its temperature across its cloud point) with a laser beam for causing the light-absorbing material to absorb energy of the beam and generate a heat, whereby elevating the temperature of the polymer blend near the light-absorbing material to a temperature of above the cloud point to change the phase condition of the polymer blend into a state which is different from the original state before the elevation of the temperature; and rapidly cooling the polymer blend to fix the polymer blend in its changed phase condition. An information recording medium preferably employed for the method is also disclosed.