Optical information recording medium and recording/reproducing device

An optical information recording medium comprising:

• a recording layer in which at least one recording mark is formed;
• a super-resolution functional layer that, when irradiated by a laser beam focused by a focusing optical system, enables information to be reproduced from the recording mark having a length shorter than a diffraction limit determined by optical performance of the focusing optical system and wavelength of the laser beam;
• and
• a protective layer that covers the recording layer and the super-resolution functional layer and transmits the laser beam;
• wherein:
• letting n be the refractive index of the protective layer with respect to the laser beam, λ be the wavelength of the laser beam, and ds be the depth of the recording mark,
• the super-resolution functional layer is configured to form both a first type of peak and a second type of peak when the depth ds of the recording mark having a length shorter than the diffraction limit is within a range from 0 to λ/2, the first type of peak being a maximum of a reproduced signal amplitude, the second type of peak being a local maximum at which the reproduced signal amplitude is less than at the first type of peak, and
• the depth ds of the recording mark is a pit depth that produces the first type of peak or a pit depth that produces the second type of peak.