Sony Corporation

Sony Semiconductor Solutions Corporation

Kotaro Kurokawa

Koichi Yasuda

Takeshi Yamasaki

Shigeki Takagawa

Masanobu Yamamoto

Daisuke Ueda

Tomomi Yukumoto

Toshihiro Horigome

Koji Sekiguchi

Kenji Yamamoto

Kimihiro Saito

Yuji Kuroda

Yo Ota

A reproduction apparatus dividing a cross section of superposed light into a plurality of regions in a tangential and/or radial direction includes: an optical system configured to generate each of a first set of signal light and reference light having a phase difference of approximately 0&#xb0;, a second set of signal light and reference light having a phase difference of approximately 180&#xb0;, a third set of signal light and reference light having a phase difference of approximately 90&#xb0;, and a fourth set of signal light and reference light having a phase difference of approximately 270&#xb0;, using a plurality of superposed light beams corresponding to the divided regions; an optical receiver configured to output signals corresponding to the sets of the signal light and the reference light; and a circuit configured to compute signals as differences between the signals, and obtain a reproduction signal by computation from the computed signals.

Reproduction apparatus and reproduction method

Provided is a reproducing apparatus including: a reproduction signal generating circuit that calculates a first difference signal which is a difference between a first light receiving signal obtained by the first light receiving element and a second light receiving signal obtained by the second light receiving element, and a second difference signal which is a difference between a third light receiving signal obtained by the third light receiving element and a fourth light receiving signal obtained by the fourth light receiving element, and uses the first difference signal, the second difference signal, a phase difference between a crosstalk component and an average phase of the signal light beam, and an optical path length difference between the signal light beam and the reference light beam to obtain a reproduction signal; and a phase extraction circuit that obtains a successive change amount and updates with a successive variation.

Reproducing apparatus and reproducing method

The present invention relates to an information recording medium that has good enough recording characteristics even without containing Pd. The information recording medium has a recording layer including an oxide of Mn in which Mn atoms are partially or fully present as Mn with a valence of +4.

Recording layer, information recording medium, and target

An optical recording medium includes a support substrate, and a semi-transmissive recording layer including a first dielectric layer, a semi-transmissive semi-reflective layer, a second dielectric layer, a phase-change recording material layer, and a third dielectric layer which are laminated in that order from the support substrate side. The semi-transmissive semi-reflective layer is composed of silver, and the first dielectric layer includes a composite oxide layer using niobium oxide.

Optical recording medium

An optical recording medium includes a support substrate and a semi-transmissive recording layer. The semi-transmissive recording layer includes a first dielectric layer, a semi-transmissive semi-reflective layer, a second dielectric layer, a phase change recording material layer, and a third dielectric layer that are sequentially stacked in that order on the support substrate. The semi-transmissive semi-reflective layer contains silver. The second dielectric layer has a stack structure including a lower layer disposed at the interface on the semi-transmissive semi-reflective layer side and an upper layer disposed on the phase change recording material layer side of the lower layer. The lower layer is composed of indium oxide or a composite oxide of indium oxide and tin oxide. The upper layer is composed of tantalum oxide, gallium oxide, zirconium oxide, or niobium oxide.

An optical information recording medium includes: a supporting substrate; a light-transmitting protective layer which becomes a layer on the incident side of recording and reproducing laser light; and an information recording layer intervening between the supporting substrate and the light-transmitting protective layer, wherein the information recording layer includes a phase-change material layer, a dielectric layer and a metal layer in this order from the incident side of laser light; and the dielectric layer is constituted of, as a main component, (InO)(SnO), wherein x is satisfied with the relationship of (0.4&#x3c;x&#x2266;0.7).

Optical information recording medium

An optical information recording medium is provided and includes a supporting substrate, a light-transmissive protective layer, information recording layers, and at least one interlayer transparent to a laser beam having a wavelength of 400 to 410 nm. Among the information recording layers, one or a plurality of information recording layers other than the information recording layer closest to the supporting substrate each function as a semi-transmissive information recording layer that transmits the laser beam. Some or all of the one or the plurality of semi-transmissive information recording layer include, from the laser beam incident side, a first dielectric portion having a refractive index of 2.4 or more for the wavelength of the laser beam, a recording material portion having a thickness of at least 5.2 nm, a second dielectric portion, a metal portion having a thickness of at least 7 nm, and a third dielectric portion in that order.

An initialization method of an optical recording medium having a plurality of optical recording layers capable of reducing initialization unevenness due to light interference caused at the time of initialization without deteriorating information recording/reproducing signal characteristics of the optical recording layers is provided. An initialization method of an optical recording medium, wherein a second optical recording layer and a first optical recording layer are stacked via an interlayer on a substrate in an order, a protective layer is formed further on the first optical recording layer, a recording film in the first optical recording layer comprises a phase change type recording material, and a recording/reproducing light is irradiated from the protective film side at the time of recording/reproducing, and in a step of initializing by irradiating an initializing light on the first optical recording layer from the protective film side, the first optical recording layer is initialized so that an energy density IDper unit area of an incident light of the initializing light at respective points in a light convergence region converged on the first optical recording layer and an energy density IDper unit area at the respective points of the light convergence region of a return light, which is the initializing light transmitted through the first optical recording layer to reach the second optical recording layer, reflected on the second optical recording layer and again returned to the first optical recording layer, satisfy ID/ID&#x2266;0.002.

Initialization method of optical recording medium

The present invention is a multilayer optical disc formed of a plurality of information recording sections having a phase change recording layer. A first information recording section provided at a laser-incident side uses, as a recording material, a phase change recording material which uses Sb and Te as major components and satisfies their ratio of 2.3&#x3c;Sb/Te&#x2266;4.0 according to the atomic ratio. Since this phase change recording material provides a fast crystallization speed, it is possible to stably record, reproduce, and rewrite an information signal at a high transfer rate.

Multilayer phase-change type optical disc capable of recording and reproducing information at high transfer rate

An initialization method of an optical recording medium having a plurality of optical recording layers capable of reducing uneven initialization due to light interference caused at the time of initialization without deterioration of information recording/reproducing signal characteristics of the recording layers is provided. An initialization method of an optical recording medium, wherein a second optical recording layer and a first optical recording layer are successively stacked via an interlayer on a substrate, a protective layer is formed further on the first optical recording layer, a recording film in the first optical recording layer comprises a phase change type recording material, and a recording/reproducing light is irradiated from the protective film side at the time of recording/reproducing, a material composing the interlayer has a sufficient transmittance for a wavelength of the recording/reproducing light and absorption for an initializing light, and, in a step of initializing by irradiating an initializing light on the first optical recording layer from the protective film side, laser light having a wavelength range of 200 nm to 400 nm is used as the initializing light.

Initialization nonuniformity due to interference of light which occurs during an initialization process is reduced without causing degradation in the characteristic of signals recorded/reproduced on/from respective recording layers. A multilayer optical disk comprising at least a first information recording layer and a second information recording layer formed, on a substrate, into a multilayer structure with an intermediate layer disposed therebetween is illuminated with initializing light from the side of the first information recording layer to initialize the first information recording layer formed of a phase-change material serving as a recording material. The illumination with the initializing light is performed such that the numerical aperture NA of an objective lens used for illumination with the illuminating light, the longitudinal length L of the beam size of the initializing light, the thickness D of the intermediate layer, and the ratio R1 of the amount of light striking the first information recording layer after passing through the first information recording layer and being reflected by the second information recording layer to the amount of light incident on the first information recording layer satisfy the following relation for a wavelength &lgr;i of the initializing light: L&times;R1 &lE;25&lsqb;1&minus;exp(&minus;0.0004&times; &times;D )&rsqb;.

Multilayer optical disk and method of initializing the same

A multi-layered optical disc having its recording unit comprised of plural information recording layers, in which two or more information recording layers are layered on a substrate 0.3 to 1.2 mm in thickness, with the interposition of a transparent layer, to from a recording unit, a light transmitting protective layer is formed on the recording unit to a thickness of 10 to 177 &mgr;m, and in which the light is illuminated from the side of the light transmitting protective layer to effect recording and/or reproduction of information signals. At least one of the information recording layers except the information recording layer formed at a remotest position from the light transmitting protective layer has a phase change material as a recording material. A refractive index nc and an extinction coefficient kc in the crystallized state and a refractive index na and an extinction coefficient ka in the amorphous state of the phase change material constituting the first information recording layer as counted from the light transmitting protective layer satisfy the relationship of (nc /na )&lE;12, (kc /ka )&lE;12 and (kc /ka )&lE;5 (nc /na ), where the cases of kc /ka <1 and nc /na <1 are excluded.

Multi-layered optical disc

A multi-layered optical disc having superior recording/reproducing characteristics, in which the recording density in three-dimensional direction can be increased to increase the recording capacity, and its manufacturing method. A multi-layered optical disc,has a light reflecting layer,a second information recording layer,a transparent layer,a first information recording layer,and a light-transmitting layer,sequentially formed on a major surface,of its substrate,The laser light is illuminated from the light-transmitting layer,of the multi-layered optical disc,to record and/or reproduce information signals.

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Kanagawa, Japan

Kotaro Kurokawa