Non-linear optical saturable absorber layer in an optical disk to discriminate wavelength above or below a threshold level of intensity
AssigneeHitachi, Ltd.
InventorsTakeshi Nakao, Akira Arimoto, Kensuke Ogawa, Hirofumi Sukeda, Hisataka Sugiyama
Life of this patent
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Abstract
An information recording medium for suppressing the interferences of bits before and after reproduction and improving the optical resolution with saturable absorber 102 disposed adjacent or in an information recording medium layer 103. The recorded information is detected only from a region having a predetermined optical intensity or more of the focused spot so that minute information bits smaller than the optical resolution can be reproduced to improve the recording density of an optical disk drive drastically.
Claims16
An optical information device, comprising:
- an information recording layer having a stored information correlated pattern for one of transmitting or reflecting an incident beam of light in a corresponding information related beam of light;
- a non-linear optical saturable absorber that is effectively transparent to light of a first wavelength, that is effectively transparent to light of a second wavelength above a threshold level of intensity, and that is opaque to light of the second wavelength below the threshold level of intensity;
- recording laser means for producing a first beam of recording light at the first wavelength;
- optical means for shaping the first beam of light and directing it along a path intersecting the saturable absorber and the information recording layer;
- separate laser means for producing a second beam of reproducing light of the second wavelength;
- second optical means for shaping the second beam of light and directing it along a path intersecting the saturable absorber and the information recording layer;
- and
- optical means for receiving light reflected by or transmitted through the information recording layer from the second beam for reading information.
An optical information device, comprising:
- an information recording layer having a stored information correlated pattern for one of transmitting or reflecting an incident beam of light in a corresponding information related beam of light;
- a non-linear optical saturable absorber that is effectively transparent to light of a wavelength above a threshold level of intensity, and that is opaque to light of the wavelength below the threshold level of intensity;
- laser means for producing a first beam of light at the wavelength;
- optical means for shaping the first beam of light and directing it along a path intersecting the saturable absorber and the information recording layer;
- and
- optical means for receiving light reflected by or transmitted through the information recording layer for reading information.
Dependencies are inferred from the claim text.