Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse...
Reexamination Certificate
1998-06-16
2001-07-17
Neyzari, Ali (Department: 2651)
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
C369S275100, C428S690000
Reexamination Certificate
active
06262949
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer resonance device for use in a device utilizing a magneto-optical effect and to a magneto-optical recording medium for recording/reproducing information through a magneto-optical recording/reproducing operation.
In the recent PC (personal computer) environment for dealing with dynamic image data, a magneto-optical recording medium, which has been widely used as a data recording device for a computer, is required to have a larger recording capacity, namely, there is a demand for a magneto-optical disk capable of high density recording. In order to increase a packing density, it is necessary to form short recording marks, but such short recording marks decrease a reproducing signal output due to waveform interference between the marks. Therefore, as a reproducing method for obtaining a reproducing signal without causing the waveform interference between the marks, various types of magnetically induced super resolution technique have been proposed. However, a magnetically induced super resolution medium has a structure including stacked layers of plural magnetic layers respectively having different magnetic characteristics, and hence, it is very difficult to control the magnetic characteristic and the exchange coupled force among the magnetic layers. Therefore, mass-production of such a medium is difficult. In addition, it is disadvantageously necessary to set recording/reproducing apparatus in accordance with the layer structure of the medium.
Furthermore, in a general magneto-optical disk, for example, in a magneto-optical disk having a structure including a SiN layer, a TbFeCo layer, another SiN layer and an aluminum layer successively stacked in this order on a substrate, an incident laser beam is made not to be reflected within the layers in order to attain a large magneto-optical effect. However, even in a magneto-optical disk using this non-reflection condition, it is impossible to obtain a Kerr rotation angle larger than one degree, and hence, such a disk is not suitable to reproducing short recording marks. Moreover, in a magneto-optical disk utilizing optics using evanescent light, that is, so-called near-filed optics, a reproducing signal output is so small that a medium for attaining a larger magneto-optical effect is demanded.
On the other hand, in the field of an optical isolator, a garnet monocrystal layer including YIG (yttrium-iron-garnet) as a main component is used, but the use is limited because light loss cannot be avoided. As a countermeasure, the present inventors and applicant have found that an optical isolator having a multilayer structure formed by alternately stacking a garnet monocrystal layer including YIG as a main component and a dielectric substance can attain a large magneto-optical effect and a high transmittance and can be free from light loss. Also, as a result of development of this finding, the present inventors and applicant have proposed a magneto-optical multilayer layer in Japanese Patent Application Laid-Open No.10-54965 (1998).
The magneto-optical multilayer layer disclosed in Japanese Patent Application Laid-Open No.10-54965 (1998) has a structure in which a magnetic substance and a dielectric substance are alternately stacked with their thicknesses irregularized, and can attain a very large magneto-optical effect. However, the number of stacked layers is large, and hence, the total thickness is large. Therefore, this magneto-optical multilayer layer is disadvantageously difficult to practically apply to a device utilizing a magneto-optical effect such as a microcavity and the aforementioned magneto-optical recording medium.
BRIEF SUMMARY OF THE INVENTION
The present invention was devised to overcome the aforementioned problems. One object of the invention is providing a multilayer resonance device which can attain a large magneto-optical effect with a practical thickness by disposing regularly stacked layers each formed by alternately stacking a magnetic substance and a dielectric substance with thickness regularity, and an irregular layer including a magnetic substance and having a thickness disaccording with the thickness regularity to be sandwiched therebetween.
Another object of the invention is providing a multilayer resonance device which can attain a large magneto-optical effect with a practical thickness by disposing regularly stacked layers each formed by alternately stacking different dielectric substances with thickness regularity, and an irregular layer including a magnetic substance and having a thickness disaccording with the thickness regularity to be sandwiched therebetween.
Still another object of the invention is providing a magneto-optical recording medium capable of high output reproduction even when a light beam with a short wavelength is used by disposing the aforementioned multilayer resonance device on a substrate.
The multilayer resonance device of this invention comprises two regularly stacked layers each formed by alternately stacking a magnetic substance and a dielectric substance with thickness regularity; and an irregular layer including at least a magnetic substance, disposed between the regularly stacked layers and having a thickness disaccording with the thickness regularity.
Thus, reflection layers each formed by alternately stacking the magnetic substance and the dielectric substance are disposed so as to sandwich the magnetic substance, and hence, a large rotation of a polarization plane can be attained.
Alternatively, the multilayer resonance device of this invention comprises two regularly stacked layers each formed by alternately stacking different dielectric substances with thickness regularity; and an irregular layer including at least a magnetic substance, disposed between the regularly stacked layers and having a thickness disaccording with the thickness regularity.
Thus, the dielectric substances are alternately stacked, and hence, a multilayer layer working as a reflection layer can be easily formed.
In the multilayer resonance device, the regularly stacked layers together have a stacked structure symmetrical with respect to the irregular layer.
Since the layer structure is symmetrical with respect to the irregular layer, the resonance effect can be enhanced.
Alternatively, the multilayer resonance device of this invention comprises first and second optical layers having different optical characteristics and respectively having first and second thicknesses determined in accordance with the optical characteristics thereof, which are alternately stacked to form a multilayer stacked layer; and a magnetic layer disposed substantially at the center of the multilayer stacked layer and having a thickness different from the first and second thicknesses.
Thus, the optical layers having peculiar optical characteristics, such as a magnetic substance and a dielectric substance, are stacked into a predetermined thickness. Therefore, an interference layer in which light is localized at the center is formed, so that the magnetic layer disposed substantially at the center of the multilayer resonance layers can exhibit a large magneto-optical effect.
The magneto-optical recording medium of this invention comprises a first regularly stacked layer formed by alternately stacking different dielectric substances with thickness regularity; a magnetic layer, having a thickness disaccording with the thickness regularity, for recording and storing information; and a second regularly stacked layer with the same thickness regularity as the first regularly stacked layer, wherein the first regularly stacked layer, the magnetic layer and the second regularly stacked layer are stacked in this order.
Accordingly, a light beam irradiating through a substrate is resonated between the first regularly stacked layer, the magnetic layer and the second regularly stacked layer, so that the magnetic layer for recording and storing information can attain a large magneto-optical effect.
In the magneto-optical recording medium, the first regularly stacked layer
Abe Masanori
Arai Ken-ichi
Fujii Toshitaka
Inoue Mitsuteru
Matsumoto Koji
Fujitsu Limited
Greer Burns & Crain Ltd.
Neyzari Ali
LandOfFree
Multilayer resonance device and magneto-optical recording... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multilayer resonance device and magneto-optical recording..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer resonance device and magneto-optical recording... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482655