Optical recording medium, and method and apparatus for optical recording and reproducing thereof

An optical recording medium comprising:

• a first information layer, an intermediate layer and a second information layer sequentially disposed between a first substrate and a second substrate,
• wherein each information layer comprises a recording layer comprising a phase-change recording material and a groove is formed along the recording track,
• wherein a laser beam at a wavelength λ is irradiated from the first substrate to perform any one of recording and reproducing of information by optical power modulation of binary or more, and
• wherein when the refraction index of the first substrate being n1, the refraction index of the intermediate layer being n2, the groove depth, the groove width and the track pitch of the first information layer being d1, w1 and p1 respectively and the groove depth, the groove width and the track pitch of the second information layer being d2, w2 and p2 respectively, the following conditions are satisfied:
• 0.9λ/16n1≦d1≦3λ/16n1
• 0.9λ/16n2≦d2≦3λ/16n2
• 0.2≦w1/p1≦0.6
• 0.2≦w2/p2≦0.6

A recording and reproducing method of an optical recording medium, wherein recording and reproducing of information are performed by irradiating the laser beam at a wavelength of 350 nm to 700 nm to each information layer of the optical recording medium comprising:

• a first information layer, an intermediate layer and a second information layer sequentially disposed between a first substrate and a second substrate,
• wherein each information layer comprises a recordable recording layer comprising an organic dye and a groove is formed along the recording track,
• wherein a laser beam at a wavelength λ is irradiated from the first substrate side to perform any one of recording and reproducing of information by optical power modulation of binary or more, and wherein when the refraction index of the first substrate being n1, the refraction index of the intermediate layer being n2, the groove depth, the groove width and the track pitch of the first information layer being d1, w1 and p1 respectively and the groove depth, the groove width and the track pitch of the second information layer being d2, w2 and p2 respectively, the following conditions are satisfied:
• 4λ/16n1≦d1≦7λ/16n1
• λ/16n2≦d2≦3λ/16n2 or 4λ/16n2≦d2≦7λ/16n2
• 0.2≦wi/p1≦0.55
• 0.2≦w2/p2≦0.55, and
• wherein the organic dye is a compound having a formula:
• or the optical recording medium comprising:
• a first information layer, an intermediate layer and a second information layer sequentially disposed between a first substrate and a second substrate,
• wherein each information layer comprises a recording layer comprising a phase-change recording material and a groove is formed along the recording track,
• wherein a laser beam at a wavelength λ is irradiated from the first substrate to perform any one of recording and reproducing of information by optical power modulation of binary or more, and
• wherein when the refraction index of the first substrate being n1, the refraction index of the intermediate layer being n2, the groove depth, the groove width and the track pitch of the first information layer being d1, w1 and p1 respectively and the groove depth, the groove width and the track pitch of the second information layer being d2, w2 and p2 respectively, the following conditions are satisfied:
• 0.9λ/16n1≦d1≦3λ/16n1
• 0.9λ/16n2≦d2≦3λ/16n2
• 0.2≦w1/p1≦0.49
• 0.2≦w2/p2≦0.47.

An apparatus for performing recording and reproducing of the optical recording medium comprising:

• a laser beam source from which a laser beam at a wavelength of 350 nm to 700 nm is irradiated, and
• a layer identifying unit and a layer switching unit for forming and dictating a mark on each information layer by irradiating the laser beam from the substrate side,
• wherein the optical recording medium is the optical recording medium comprising:
• a first information layer, an intermediate layer and a second information layer sequentially disposed between a first substrate and a second substrate,
• wherein each information layer comprises a recordable recording layer comprising an organic dye and a groove is formed along the recording track,
• wherein a laser beam at a wavelength λ is irradiated from the first substrate side to perform any one of recording and reproducing of information by optical power modulation of binary or more, and
• wherein when the refraction index of the first substrate being n1, the refraction index of the intermediate layer being n2, the groove depth, the groove width and the track pitch of the first information layer being d1, w1 and p1 respectively and the groove depth, the groove width and the track pitch of the second information layer being d2, w2 and p2 respectively, the following conditions are satisfied:
• 4λ/16n1≦d1≦7λ/16n1
• λ/16n2≦d2≦3λ/16n2 or 4λ/16n2≦d2≦7λ/16n2
• 0.2≦w1/p1≦0.55
• 0.2≦w2/p2≦0.55, and
• wherein the organic dye is a compound having a formula:
• or the optical recording medium comprising:
• a first information layer, an intermediate layer and a second information layer sequentially disposed between a first substrate and a second substrate,
• wherein each information layer comprises a recording layer comprising a phase-change recording material and a groove is formed along the recording track,
• wherein a laser beam at a wavelength λ is irradiated from the first substrate to perform any one of recording and reproducing of information by optical power modulation of binary or more, and
• wherein when the refraction index of the first substrate being n1, the refraction index of the intermediate layer being n2, the groove depth, the groove width and the track pitch of the first information layer being d1, w1 and p1 respectively and the groove depth, the groove width and the track pitch of the second information layer being d2, w2 and p2 respectively, the following conditions are satisfied:
• 0.9λ/16n1≦d1≦3λ/16n1
• 0.9λ/16n2≦d2≦3λ/16n2
• 0.2≦w1/p1≦0.49
• 0.2≦w2/p2≦0.47