Tdk Corporation

Tdk Corpoartion

Hajime Utsunomiya

Hiroyasu Inoue

Tatsuya Kato

Hideki Hirata

Takashi Kikukawa

Koji Mishima

Hiroshi Shingai

Masaki Aoshima

Masanori Kosuda

Kenji Uchiyama

Isamu Kuribayashi

Masanori Shibahara

Suguru Takayama

Yoshitomo Tanaka

Tetsuro Mizushima

Toshiki Aoi

Hideki Ishizaki

Makoto Takahashi

Takuya Tsukagoshi

Hitoshi Arai

Tsuyoshi Komaki

Yoshinori Sato

Takashi Yamada

Hiroshi Tanabe

Narutoshi Fukuzawa

Noriyuki Kawano

Tatsuhiro Kobayashi

Giichi Shibuya

Kenji Yoneyama

Tetsuya Nishiyama

Hiroshi Takasaki

Hisaji Oyake

Katsuaki Yanagiuchi

Takao Saito

The optical modulator includes an optical modulation element having a first optical waveguide, a second optical waveguide, a first electrode which applies an electric field to the first optical waveguide, and a second electrode which applies an electric field to the second optical waveguide, and a control unit configured to control an applied voltage between the first electrode and the second electrode. When a half-wave voltage of the optical modulation element is Vπ and a null point voltage of the optical modulation element is Vn, the control unit sets an operating point Vd in a range of Vn+0.50Vπ≤Vd≤Vn+0.75Vπ or Vn−0.75Vπ≤Vd≤Vn−0.50Vπ and sets an applied voltage width Vpp, which is an amplitude of an applied voltage applied to the optical modulation element, in a range of 0.22Vπ≤Vpp≤0.50Vπ.

Optical modulator and driving method of optical modulation element

This optical modulator includes an optical modulation element having a first optical waveguide, a second optical waveguide, a first electrode configured to apply an electric field to the first optical waveguide, and a second electrode configured to apply an electric field to the second optical waveguide; and a control unit configured to control an applied voltage between the first electrode and the second electrode. The control unit sets Vpp to 0.06×Vπ≤Vpp≤0.4×Vπ when a half-wavelength voltage of the optical modulation element is Vπ and an applied voltage width that is an amplitude of an applied voltage applied to the optical modulation element is Vpp, and sets Vn≤Vmin≤Vn+0.29×Vπ or Vn−0.29×Vπ≤Vmax≤Vn when a minimum value and a maximum value of a voltage applied to the optical modulation element are respectively Vmin and Vmax and a null point voltage of the optical modulation element is Vn.

Optical modulator and method for driving optical modulation element

This optical modulation element includes a first optical waveguide, a second optical waveguide, a first electrode for applying an electric field to the first optical waveguide, and a second electrode for applying an electric field to the second optical waveguide. The first optical waveguide and the second optical waveguide each include a ridge-shaped portion protruding from a first surface of a lithium niobate film. A first interaction length Lthat is a length of a part of the first electrode overlapping the first optical waveguide in a longitudinal direction is 0.9 mm or more and 20 mm or less. A second interaction length Lthat is a length of a part of the second electrode overlapping the second optical waveguide in the longitudinal direction is 0.9 mm or more and 20 mm or less.

Optical modulation element and method for driving optical modulation element

A method and apparatus for controlling a video camera recorder or the like, capable of flexibly meeting user demands for image quality, recording time, etc. When recording information on a rewritable optical recording medium, the recording mode for the optical recording medium is selected at least from between write-once and rewritable based on a set recording rate. Before recording, the recording status of the optical recording medium is also determined at least between an unrecorded area and a recorded area.

Method for controlling recorder and apparatus for controlling recorder

An optical head device (optical head) for a multi-layered optical recording medium has a focus control mechanism that makes use of astigmatism. The focus control mechanism has a sensor lens that includes a cylindrical lens. The focus control mechanism causes a light beam having passed through the sensor lens to have astigmatism, thereby being focused linearly in the Y direction on a front focal line located closer to the sensor lens and focused linearly in the X direction at a rear focal line located farther therefrom. The optical head also includes a photodetector which is disposed between the front focal line and the rear focal line to detect a focal position from the shape of a light beam. At the position of the front focal line, a shield plate with a window portion is disposed. The window portion has a size so as to allow the focal line to pass therethrough and shield stray light reflected from an unfocused recording layer.

Optical head device and optical recording and reading system

A next-generation optical recording medium has two or more information layers which include a translucent information layer. The translucent information layer has a recording film and an interface layer, provided adjacent to the recording film on the side of the light incident surface. The recording film is made of a phase change material having SbTeGeelements and elemental ratios. Y satisfies 5&#x2266;y&#x2266;15 and z satisfies 5&#x2266;z&#x2266;15. When In having an elemental ratio of a is further added and x+y+z+a=100 holds, a satisfies 4&#x2266;a&#x2266;15. The interface layer comprises of ZrO&#x2014;CrOfilm thickness of which is in a range of from 2 nm to 10 nm. When ZrO:CrO&#x2550;C:D (mol %), the compositional ratios ZrOand CrOin the ZrO&#x2014;CrOfilm, holds, the C satisfies 20&#x2266;C&#x2266;90, and the D satisfies 10&#x2266;D&#x2266;80, and the C and the D satisfy C+D=100. The ZrOis stabilized ZrOwhich contains YO, when ZrO:YO=(100&#x2212;X):X (mol %), the compositional ratios ZrOand YOin the stabilized ZrO, holds, the X satisfies 2&#x2266;X&#x2266;10.

Optical recording medium and recording film material

An information readout method for an optical information medium comprising an information recording layer having pits or recorded marks representative of information data involves the step of irradiating a laser beam to the information recording layer through an objective lens for providing readings of the pits or recorded marks. When the laser beam has a wavelength &#x3bb; of 400 to 410 nm, the objective lens has a numerical aperture NA of 0.70 to 0.85, and the pits or recorded marks have a minimum size Pof up to 0.36&#x3bb;/NA, readout is carried out at a power Pr of at least 0.4 mW for the laser beam. When the laser beam has a wavelength &#x3bb; of 630 to 670 nm, the objective lens has a numerical aperture NA of 0.60 to 0.65, and the pits or recorded marks have a minimum size Pof up to 0.36&#x3bb;/NA, readout is carried out at a power Pr of at least 1.0 mW for the laser beam. Pits or recorded marks of a size approximate to the resolution limit determined by diffraction can be read out at a high C/N.

Information readout method for non mask layer type optical information medium

It is an object of the present invention to provide a method of recording information to an optical recording medium that is suited to achieving high data transfer rates. The method of recording information according to the present invention is adapted for recording information to an optical recording medium by forming on the optical recording medium a plurality of recording marks selected from a group consisting of several types of recording marks each with different lengths, wherein a bottom power of a laser beam used for forming at least one recording mark contained in the group is set to be higher than a reproducing power of a laser beam used for reproducing information. According to the present invention, since the bottom power helps to erase a recording mark, it is possible to maintain a high erase efficiency even when information is recorded by setting a high data transfer rate.

Method and apparatus for recording information on an optical recording medium

In an optical information medium having an information bearing surface having projections and depressions and/or capable of forming recorded marks, a functional layer is added. The information borne on the information bearing surface can be read by using reading light of a wavelength longer than 4NA&#xb7;Pwherein Pis the minimum size of the projections and depressions or the recorded marks and NA is the numerical aperture of a reading optical system, setting the power of the reading light within such a range that the functional layer does not change its complex index of refraction, and irradiating the reading light to the information bearing surface constructed by the functional layer or to the information bearing surface through the functional layer or to the functional layer through the information bearing surface. The medium enables reading at a high resolution beyond the diffraction limit.

Optical information medium including an information bearing surface and a functional layer, and reading method

In a data recording and readingout system in which data is recorded and readout, or is readout on, or from an optical recording mediumby irradiating a laser beam having a wavelength '&#x3bb;' via an objective lens of a numerical aperture 'NA' onto said optical recording medium, while the optical recording medium contains a layered structure formed by sandwiching a dielectric layerbetween a recording layerand an optical absorption layerwith respect to the optical recording mediumarranged in such a manner that data recorded by a recorded mark train can be readout and the recorded mark train contains a recorded mark smaller than, or equal to a limit of resolution, the laser beam is irradiated via the objective lens and a solid immersion lens having a refractive index &#x201c;n&#x201d; which is positioned between the optical recording medium and the objective lens, so that the data is recorded and readout, or is readout with respect to the optical recording medium by a recorded mark train which contains a recorded mark smaller than, equal to &#x201c;&#x3bb;&#x201d;/(4&#xb7;n&#xb7;NA).&#x201d;

Data recording and readingout system

An optical recording medium includes a substrate, a first recording layer formed on the substrate and containing an element selected from the group consisting of Si, Ge, C, Sn, Zn and Cu as a primary component, and a second recording layer located in the vicinity of the first recording layer and containing Al as a primary component, the optical recording medium being constituted to be irradiated by a laser beam projected onto the side opposite from the substrate and the total thickness of the first recording layer and the second recording layer being equal to or thinner than 40 nm. According to the thus constituted optical recording medium, it is possible to decrease a noise level and improve a C/N ratio in a reproduced signal.

Optical recording medium and method for optically recording data in the same

An optical information recording medium which makes it possible to reduce the noise level, improve the C/N ratio and store record data for a long time period. An optical information recording medium has a recording layer formed on a substrate, for having a laser beam irradiated thereto for recording and reproduction of record data. The recording layer includes a first sub-recording film and a second sub-recording film. The first sub-recording film is formed of a first material containing Si as the main component. The second sub-recording film is formed of a second material containing Al as the main component and having Au added thereto, and disposed in the vicinity of the first recording film. The laser beam is irradiated to the recording layer via a light transmitting layer formed in a manner covering the recording layer side.

Optical information recording medium

An optical information recording medium which is capable of performing high-density recording of record data, and storing the recorded data for a long time period such that the recorded data can be normally reproduced during the long time period. An optical information recording medium has a recording layer formed on a substrate, for having a laser beam irradiated thereto for recording and reproduction of record data. The recording layer includes a first sub-recording film and a second sub-recording film. The first sub-recording film is formed of a first material containing Si as the main component. The second sub-recording film is formed of a second material containing Cu as the main component and having Au added thereto, and disposed in the vicinity of the first recording film.

An optical information recording medium which makes it possible to reduce the noise level and improve the C/N ratio. An optical information recording medium has a recording layer formed on a substrate, for having a laser beam irradiated thereto for recording and reproduction of record data. The recording layer includes a first sub-recording film and a second sub-recording film. The first sub-recording film is formed of a first material containing Si as the main component. The second sub-recording film is formed of a second material containing Zn as the main component and having Cu added thereto, and disposed in the vicinity of the first recording film. The laser beam is irradiated to the recording layer via a light transmitting layer formed in a manner covering the recording layer side.

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Tokyo, Japan

Hajime Utsunomiya