Optical information recording medium, method of recording and reproducing, and optical recording and reproducing system

An optical information recording medium, comprising one or more information layers including recording layers, respectively, each recording layer containing a material that can exhibit transition between two optically different states in response to irradiation with a laser beam as a main component,

• wherein, in at least one of the recording layers, one of the two states of said material is an amorphous states,
• wherein said material has an energy gap ranging from 0.9 eV to 2.0 eV in the amorphous state,
• wherein the information layer including the recording layer that contains said material as a main component thereof has a light transmittance of not less than 30% when irradiated with a laser beam having a wavelength ranging from 300 nm to 450 nm,
• wherein at least one of the recording layers contains a material that can exhibit a reversible transition between a crystalline state and an amorphous state as a main component,
• wherein the recording layer containing the material that can exhibit a reversible transition between the crystalline state and the amorphous state as a main component satisfies a relationship expressed as:
• E0(c)<E0(a)−0.15
• wherein E0(c) represents an energy gap of said material in the crystalline state, and E0(a) represents an energy gap of said material in the amorphous state.