Nec Corporation

Kabushiki Kaisha Toshiba

Ryuichi Katayama

Yutaka Yamanaka

Chosaku Noda

Masatsugu Ogawa

Eiichi Ueda

Shin Tominaga

Hiroharu Satoh

Hideaki Ohsawa

Mizuho Tomiyama

Naotoshi Iwazawa

Motoaki Shimizu

Daisuke Eto

Takeharu Shibatoko

Taku Tsuboi

Hidekazu Shirakawa

Masahumi Miura

Provided is a light-emitting element having high luminance and high directivity and emitting light in a controlled polarization state. The light-emitting element comprises substrateand light emitting partdisposed on substratefor emitting light in which light intensity of a polarization component in first direction x parallel to substrateis higher than light intensities of polarization components in other directions. Light emitting partincludes active layerfor generating light and a plurality of structural bodiesdisposed on a light-emitting side of light emitting partwith respect to active layerand arrayed two-dimensionally along a surface substantially parallel to active layer. Each of structural bodieshas width walong first direction x and width walong second direction y perpendicular to first direction x, width walong first direction x and width walong second direction y being different from each other in a cross section parallel to active layer. Structural bodiesare arrayed periodically at first pitch palong first direction x and arrayed periodically at second pitch p, which is different from first pitch p, along second direction y.

Light emitting element having structural bodies arrayed at a first pitch along a first direction and arrayed at a second pitch different from said first pitch along a second direction and projection display device provided with same

The light emitting element includes and active layer that produces light; a polarizer layer having a first region that allows a polarization component in a first direction in the light produced in the active layer to pass through and reflects other polarization components, and a second region that allows a polarization component in a second direction perpendicular to the first direction to pass through and reflects other polarization components; a wave plate layer having a third region and a fifth region that the light exiting from the first region enters, and a fourth region and a sixth region that the light exiting from the second region enters, the wave plate layer causing the lights that have entered the third to sixth regions to exit as lights in the same polarized state; and a reflective layer that reflects the lights reflected by the first region and the second region. The directions of optical axes of the third region and the fifth region, or the fourth region and the sixth region, are perpendicular to each other.

Polarized light emitting element for display apparatus

The present invention is intended to realize a light emitting element which is easy to fabricate, is efficient, and is able to emit light in a uniform polarization state enabling the achievement of high luminance. A light emitting element of the present invention is a light emitting element including an active layer for generating light, the light emitting element including: a first reflection layer that allows the light generated at the active layer to reflect at a reflection section in which reflection members are periodically provided, and to exit from an exiting section between the reflection members; a polarization beam splitter layer that transmits a polarized light oriented in a first direction and diffracts a polarized light oriented in a second direction orthogonal to the first direction among the light exited from the exiting section; a wave plate layer that allows the light transmitted through the polarization beam splitter layer and the light diffracted at the polarization beam splitter layer to enter, and to exit as a light of a same polarization state; and a second reflection layer that reflects the light reflected at the first reflection light.

Light emitting element and image display apparatus using the light emitting element

Provided is a wavelength plate that can increase incident angle tolerance. The wavelength plate in which a high refractive index layer and a low refractive index layer are alternately stacked, each layer having a concave-convex structure the period of which is equal to or shorter that a wavelength in one direction within a plane, includes, as periods in the thickness direction of the high refractive index layer and the low refractive index layer: a first period defined so that a used wavelength can belong to the first band of a photonic band structure; and a second period defined so that the used wavelength can belong to a wavelength side longer than the center wavelength of the second band of the photonic band structure.

Wavelength plate, light emitting element, and image display device using the light emitting element

The present invention provides a light emitting element which emits linearly polarized light, has high efficiency, can show a higher luminance and has also adequate productivity. The light emitting element that includes an active layer composed of a semiconductor which generates light includes: a polarizer layer that allows a polarized component in a first direction among the lights generated in the active layer to pass therethrough, reflects a polarized component in a second direction which is perpendicular to the first direction, is formed on a semiconductor of the same group as the active layer, and contains a semiconductor or a metal of the same group as the active layer; a reflective layer that is provided in the opposite side of the polarizer layer with respect to the active layer, and reflects light which has been reflected by the polarizer layer; and a wavelength plate layer that is provided between the polarizer layer and the reflective layer, changes polarization states of the light which has been reflected by the polarizer layer and the light which has been reflected by the reflective layer, and contains a semiconductor of the same group as the active layer.

Light emitting element and image display device using the light emitting element

A light emitting element which can emit light in a uniform polarization state at a high efficiency and a higher luminance level is realized. The light emitting element of the present invention is a light emitting element including an active layer for generating light, the light emitting element including: a polarizer layer including a first region that transmits polarized light in a first direction and reflects other light from among the light generated at the active layer, and a second region that transmits polarized light in a second direction orthogonal to the first direction and reflects other light; a wave plate layer including a third region and a fourth region that allow the lights exited from the first region and the second region to enter, and to exit as light in the same polarization state; and a reflection layer that reflects the lights reflected at the first region and the second region.

An optical information recording/reproducing device includes a liquid optical element containing a liquid crystal polymer layer in an optical head. A liquid crystal optical element drive unit drives a liquid crystal optical element having a first pattern electrode divided into a plurality of region at one side of the liquid crystal polymer layer in the optical axis direction. The first pattern electrode includes a first region arranged to surround the optical axis and second to ninth regions arranged outside the first regions in such a manner that the circumference is divided eight portions. The liquid crystal optical element drive unit applies an effective voltage to each region. The voltage applied to the respective regions of the pattern region of the liquid crystal optical element is decided in a short time so as to optimize the quality of the reproduction signal.

Optical information recording/ reproducing apparatus and optical information recording and reproducing method

An optical unit is provided with a light source; a light dividing means for dividing light emerging from the light source into a first light and a second light; a light converging means for converging the first and second lights at the same position in the recording layer in the manner that they face each other; a polarization state switching means for switching the polarization states of the first and second lights at the convergence point in the recording layer; and a light irradiation state switching means for switching between the state in which the optical cording medium is irradiated with both the first light and the second light and the state in which the optical recording medium is irradiated with only one of the first and second lights.

Optical information recording/reproducing device, optical unit, and optical information recording method

An optical information recording/reproducing device includes a liquid optical element containing a liquid crystal polymer layer in an optical head. A liquid crystal optical element drive unit drives a liquid crystal optical element having a first pattern electrode divided into a plurality of region at one side of the liquid crystal polymer layer in the optical axis direction. The first pattern electrode includes a first region arranged to surround the optical axis and second to ninth regions arranged outside the first regions in such a manner that the circumference is divided eight portions. The liquid crystal optical element drive unit applies a first effective voltage to the first region, a second effective voltage to the second and the sixth region, a third effective voltage to the third and the seventh region, a fourth effective voltage to the fourth and the eighth region, and a fifth effective voltage to the fifth and the ninth region. An average value of the second and the fourth effective voltage and an average value of the third and the fifth effective voltage are identical to the first effective voltage. The voltage applied to the respective regions of the pattern region of the liquid crystal optical element is decided in a short time so as to optimize the quality of the reproduction signal.

Optical information recording/ reproducing device and optical information recording/ reproducing method

To provide an optical head device, which can detect an excellent focus error signal for a dual layer optical recording medium, and optical information recording/reproducing device. Reflected light from a dual layer optical recording medium is diffracted by a diffractive optical element divided into four regions, and is received by a photodetector. Optical spots are equivalent to negative first order diffracted light from the four regions of the diffractive optical element, and are received by four dual-divided light receiving sections, respectively, to be used for detection a focus error signal by a Foucault's method. The four dual-divided light receiving sections are provided with positive component light receiving sections for outputting the received light as a positive component of the focus error signal and negative component light receiving sections for outputting the received light as a negative component of the focus error signal, respectively. When a signal layer of the optical recording medium is far from an objective lens by a defocusing quantity equivalent to an interval between the first layer and the second layer from a just focus position, a diffraction direction of a diffracted light generated from the reflected light from the signal layer is set so as that the diffracted light spreads to the positive component light receiving section and the negative component light receiving section, and a plurality of the positive component light receiving sections and a plurality of negative component light receiving sections are arranged.

Optical head device for detecting an error signal and an optical information recording/reproducing device

An optical head apparatus of an optical information recording/reproducing apparatus is provided with a light source. An objective lens focuses an output light emitted by said light source on a disc optical recording medium for which a groove or a pit for tracking is provided. T photo-detector receives a reflected light reflected by said optical recording medium. A polarizing splitter unit splits said output light and said reflected light. A quarter-wave plate disposed between said polarizing splitter section and said objective lens. A birefringence compensating unit reduces a change in an amplitude of a track error signal caused by birefringence in a protective layer of said optical recording medium.

Optical head apparatus and optical information recording/reproducing apparatus

Light emitted from a light source and having a wavelength of 400 nm is reflected by a beam splitter (BS), and converged on a disk according to a next-generation standard. Reflection light therefrom passes through the BS and is received by a photodetector. Light emitted from a light source and having a wavelength of 660 nm is reflected by the BS and passes through the BS, and converged on a disk according to a DVD standard. Reflection light therefrom passes through the BS and is received by the photodetector. About 50% of light emitted from a light source and having a wavelength of 780 nm is reflected by the BS. The light passes through the BS and is then converged on a disk according to a CD standard. Reflection light therefrom passes through the BS. About 50% of the light passes through the BS and is received by the photodetector. Thus, recording and reproduction can be performed on any of disks according to a next-generation standard, DVD standard, and CD standard. With respect to disks according to the next-generation standard, a high optical output is obtained during recording and a high S/N ratio is obtained during reproduction. With respect to disks according to the CD standard, the amount of light received by the photodetector does not substantially vary even when birefringence of a disk varies.

Optical head apparatus and optical information recording or reproducing apparatus

The light emitted from a semiconductor laser is divided by a diffractive optical element into three light beams which are 0th-order light as the main beam and &#xb1;1st-order diffracted lights as the sub-beams, and the track error signals by the main beam and the sub-beams are detected, respectively, by a differential phase detection method. By the effect of the diffractive optical element, the light intensity distributions of the main beam and the sub-beams become different when making incidence on an objective lens. Therefore, when there is radial tilt in a disk, the phases of the track error signals by the main beam and the sub-beams are shifted with each other. Based on the shift in the phases of the track error signals, radial tilt of the disk is detected.

Method for detecting radial tilt of optical recording medium in optical head device, optical head device, and optical information recording/reproducing device

An optical head device and an optical recording and reproducing apparatus using this optical head device, which can record information and reproduce the recorded information at any of optical recording media, such as a next generation optical recording medium, in which the wavelength of the light source is made to be shorter, the numerical aperture of the objective lens is made to be higher, and the thickness of the recording medium is made to be thinner, and conventional recording media of DVD and CD standards, are provided. A light having wavelength of 405 nm, emitted from one of optics, is inputted to an objective lens as a collimated light, and is focused on a disk having thickness of 0.1 mm. A light having wavelength of 650 nm, emitted from the other of optics, is inputted to the objective lens as a diverged light, and is focused on a disk having thickness of 0.6 mm. A spherical aberration, which remains for the light having wavelength of 650 nm, is decreased by the change of the magnification of the objective lens, further the decreased spherical aberration is decreased by using a wavelength selective filter.

Optical head device and optical recording and reproducing apparatus

Provided is an optical head device and an optical information recording or reproducing device for performing recording or reproduction to/from a plurality of types of optical recording medium, which can obtain a stable track error signal by a small size and exhibits high efficiency. Light Pand light Pemitted from a double-wavelength light source make incidence to a diffractive optical element in the same polarization directions. Diffraction gratings have a double refractive characteristic and in these areas the polarization directions of the two light beams become orthogonal. The light of 650 nm band is divided into 0th-order light and &#xb1;1st-order diffracted light in one of the diffraction grating and transmits through the other diffraction grating. The light of 780 nm band transmits through one of the diffraction grating and is divided into 0th-order light and &#xb1;1st-order diffracted light in the other diffraction grating. The two light beams are emitted from the diffractive optical element in the same polarization direction and guided towards the optical recording medium through a polarizing beam splitter and a quarter-wave plate.

Growing community of inventors

Tokyo, Japan

Ryuichi Katayama