Phase-change medium usable in phase-difference tracking

A method of forming an optical phase-change recording medium used for recording information by use of laser light, comprising:

• forming a recording layer which is able to change between an amorphous state and a crystalline state so as to record information, such that said recording layer has a thickness falling within a first range defined relative to a wavelength of the laser light;
• forming a protection layer having a thickness falling within a second range defined relative to the wavelength of the laser light;
• forming a heat releasing layer having a thickness falling within a third range defined relative to the wavelength of the laser light;
• and
• forming a transparent substrate for supporting said layers,
• wherein the first, second, and third ranges are selected such that a phase of the laser light reflected by the amorphous state and a phase of the laser light reflected by the crystalline state have a phase difference larger than a predetermined phase amount.