Abstract: A phase shift element includes a substrate and a dielectric ridge waveguide (DRW) disposed on the substrate. The DRW includes a dielectric material, and a width of the DRW is less than 500 nanometers (nm). A meta-grating includes a substrate and multiple dielectric ridge wave-guides (DRWs) disposed on the substrate.

Abstract: A method of monitoring overlay is used in a manufacturing process in which successive layers are deposited one over another to form a stack. Each layer may include a periodic structure such as a diffraction grating to be aligned with a periodic structure in another layer. The stacked periodic structures may be illuminated to form + and ? first order diffraction patterns from the periodic structures. An image of the stacked periodic structures may be captured including + and ? diffraction patterns. The + and ? diffraction patterns may be compared to calculate the overlay between successive layers.

Abstract: The operation of a circuit exhibiting a delay that is subject to a time spread as a function of process, voltage, and temperature variations is synchronized with a synchronization signal. A digital delay corresponding to the time spread is applied to the synchronization signal. The digital delay is generated via cascaded delay elements having respective delay values and by controlling the number of cascaded delay elements in the circuit that are applied to the synchronization signal.

Abstract: A system and method for providing direct read after write functionality in an optical data storage device include an optical head having a first coherent light source modulated at higher power during writing of data to the optical medium and a second coherent light source operating in a continuous wave mode at lower power while the first coherent light source is writing data. Optic components combine light from the first and second light sources and focus light from the first coherent light source to a first spot of a selected track on the optical medium and focus light from the second coherent light source to a second spot on the selected track downstream from the first spot relative to movement direction of the optical medium to read and verify the data directly after writing during the write process rather than in a separate verification process.

Abstract: An information device is an information device that records information on or reproduces information from an information recording medium (3). The information device includes a light source (14) and a near-field light generating element (9) including a resonating section (22) configured such that plasmon resonance occurs between the resonating section (22) and a recording region (4). The resonating section (22) causes the plasmon resonance when emission light from the light source is irradiated on the near-field light generating element (9). A resonance enhancing film enhances the plasmon resonance between the resonating section (22) and the recording region (4). The resonating section (22) generates near-field light and irradiates the near-field light on the recording region (4) from a recording layer side.

Abstract: Multi-level recording is quite effective for attaining a larger capacity and a higher transfer rate in the case of an optical disk; however, with conventional technologies, a SIGNAL-TO-NOISE RATIO of a signal deteriorates along with an increase in a multi-level degree, creating a factor for limitations to the multi-level degree. In order to solve problems, when optical information is recorded by use of a standing wave occurring due to interference between two light beams, at least one of the two light beams is modulated in multi-stages. Further, at the time of regeneration, a regeneration reference beam is caused to interfere with respective polarization components of a regeneration beam, the polarization components being orthogonal to each other, thereby concurrently generating not less than three interference beams differing in interference phase from each other before being detected.

Abstract: An optical pickup device includes a polarization diffraction grating to diverge an optical beam reflected from an optical disc and an optical detector to receive the optical beam diverged by the polarization diffraction grating, a polarization of 0 order diffracted light diffracted through the polarization diffraction grating is substantially perpendicular to that of a +1 order diffracted light diffracted therethrough, and a polarization filter having a plurality of domains is mounted between the polarization diffraction grating and the optical detector.

Abstract: The invention relates to a method of optical six-dimensional data storage and the apparatus based on it. This invention uses multiple beams with different wavelengths, encoded intensities and polarizations to create each group of multiple wavelength selective, reflectivity specified and polarization sensitive tiny plane or quasi-plane Bragg reflectors in a small volume crossing through multiple storage medium layers as each storage cell. The maximum storage capacity can over 10 Terabytes per disk with fast data write, read and erase speeds. In addition, the apparatus based on this method has no interlayer noise and disk rotation caused data recoding and reading quality loss, and has good compatibility with existing CD and DVD disks.

Abstract: A method comprised of transferring energy information signals onto a first intermediate carrier, with subsequent transmission of information to a receiver input and taking off the signal at the reception side of the receiver by transferring the signal onto a second intermediate carrier, for use in any area of the economy. For remote transmission of an energy information signal from animate and inanimate objects, the energy information signal of an original object is converted to an information-wave beam and brought to a coherent state by passing the beam through a crystal located between two polarizers. The converted signal is recorded onto the first intermediate carrier, entered into a transceiver and transmitted over wire and wireless communication networks together with an electromagnetic wave signal, with subsequent recording of the received signal onto the second carrier and reading off the second carrier the energy information signal peculiar to the original object.

Abstract: An optical pickup includes: a light source; a first diffractive element which diffracts light polarized in a particular direction; an objective lens; a lens actuator which shifts the objective lens so that the magnitude of shift from its initial position in a tracking direction has an upper limit of 0.3 mm to 0.6 mm; a wave plate; a second diffractive element which has two diffraction regions configured to diffract light polarized in a direction that intersects with the particular direction at right angles and which splits the write beam reflected from the optical storage medium through each diffraction region into a transmitted light beam and at least one diffracted light beam; and a photodetector which detects the transmitted light beam, the diffracted light beams that have left the two diffraction regions, and the read beam reflected from the optical storage medium.

Abstract: An information reproducing apparatus has a medium with a linear tracking mark extending in a scanning direction and a linear data mark extending in a direction orthogonal to the scanning direction. A light control unit irradiates the data mark with a first near-field light polarized in the scanning direction and irradiates the tracking mark with a second near-field light polarized in the direction orthogonal to the scanning direction. A detector detects light scattered by the data mark and the tracking mark irradiated with the first near-field light and the second near-field light, respectively. A signal processing unit processes a first output signal from the detector corresponding to the detected light scattered by the data mark and processes a second output signal from the detector corresponding to the detected light scattered by the tracking mark.

Abstract: The present invention discloses a multilevel recording method and system thereof. The multilevel recording method applied to a recording media comprises the following steps. At First, a plurality of beams are provided to a recording layer of the recording media, and the recording layer has a first structure and a second structure. Then, a first polarized reflected light of the first structure and a second polarized reflected light of the second structure are detected by a detecting unit. Then, a corresponding table is stored by a storing unit. The corresponding table comprises a relationship between the different angle of the polarized reflected light and a level of multilevel recording. Finally, the processing unit looks up the corresponding table to process multilevel recording.

Abstract: The present invention discloses a multilevel recording method and system thereof. The multilevel recording method applied to a recording media comprises the following steps. At First, a plurality of beams are provided to a recording layer of the recording media, and the recording layer has a first structure and a second structure. Then, a first polarized reflected light of the first structure and a second polarized reflected light of the second structure are detected by a detecting unit. Then, a corresponding table is stored by a storing unit. The corresponding table comprises a relationship between the different angle of the polarized reflected light and a level of multilevel recording. Finally, the processing unit looks up the corresponding table to process multilevel recording.

Abstract: An optical-pickup apparatus includes: a three-wavelength-laser diode including first-, second-, and third-laser elements to emit first-, second-, and third laser beams having first, second, and third wavelengths, respectively, the three laser elements housed in the same case; an objective lens to focus the three laser beams onto first- to third-optical-disc-signal-recording layers, respectively; a first photodetector to be irradiated with first-return light reflected from the first-optical-disc-signal-recording layer, a second photodetector to be irradiated with second- and third-return lights respectively reflected from the second- and third-optical-disc-signal-recording layers; a polarizing-beam splitter to reflect the three laser beams toward the lens, and allow the three return lights having passed through the lens to pass therethrough; a semitransparent mirror on which the three return lights having passed through the polarizing-beam splitter are incident, and which guide the first-return light toward th

Abstract: A polarization detection system structured for optical read-out of disc-shaped optical data/information storage and retrieval media with surfaces comprised of pits or marks configured as multilevel oriented nano-structures (ONS) with varying pit or mark orientations and widths. The polarization detection system comprises: an optical beam source; a stage for mounting and rotating an optical disc medium about a central axis; at least one photodetector; a beam splitter positioned in an optical path between the source and stage, for directing an incident beam from the source onto an optical disc mounted on the stage and a return beam from the disc onto the photodetector; and an optical polarizer positioned in an optical path between the beam splitter and the at least one photodetector, for detection and analysis of changes in polarization of the return beam effected by variation of the orientation of the walls and/or widths of the pits or marks of the disc.

Abstract: An information storage medium and an apparatus for recording/reproducing the same are provided. The information storage medium is provided in which repetitive recording is performed by using nanorods formed of a material capable of repeatedly changing light absorption.

Abstract: The invention relates to the writing and optical reading of high-density information. The higher energy density at the center of the reading laser beam is used for modifying the energy structure of an active layer in such a way as to make it capable of bearing surface plasmons. The coupling of the laser beam and the active layer thus modified can then excite surface plasmons in an interface between a dielectric layer and the active layer. These surface plasmons are disturbed by physical marks having very small dimensions and written in the optical storage medium; these disturbances generate a remote-field optical response which can be detected by a detector. The operation is carried out in super-resolution, the surface plasmons being generated only at the center of the laser beam and not at the periphery. It is therefore possible to write and to read again marks having dimensions of size smaller than the theoretical resolution of the optical reading system.

Abstract: An optical system for efficiently extracting plural signal beams from a bundle of rays reflected from a multilayer optical disc.

Abstract: An optical pickup for writing information to and/or for reading information from an optical disc having at least two recording layers (dual layer) provided with first and second recording layers can prevent layer crosstalk resulting from disturbing a signal reproduced from the first recording layer by a reflected light beam reflected from the second recording layer during a writing operation for writing information to the first recording layer or a reading operation for reading information from the fist recording layer. An orthogonal polarization region forming component forms an orthogonal polarization region, in which respective directions of polarization of a first light beam focused on and reflected by a first recording layer of an optical disc and a second light beam reflected by a second recording layer of the optical disc are perpendicular to each other, in a region, in which the first and the second light beam overlap each other, on a light-receiving surface of a detector.

Abstract: An optical pickup in which constituting components are arranged so that a dead space can be reduced and aberrations can also be reduced at a low manufacturing cost is provided. In an outward path for projecting a laser beam onto a recording surface 12 of an optical disc 11, the laser beam emitted from a laser diode 2 is reflected on a polarization mirror 3, polarized by a quarter wavelength plate 4, and then passed through an objective lens 5 so that the laser beam is focused on the recording surface 12 of the optical disc 11. In a returning path for receiving the laser beam reflected on the recording surface 12, the laser beam reflected on the recording surface 12 and passed through the objective lens 5 is polarized by the quarter wavelength plate 4, transmitted through the polarization mirror 3, reflected on a total reflective film 61 of the quarter wavelength plate 6, and then reflected on the polarization mirror 3 so that the laser beam is received by a photodiode 7.

Abstract: In order to provide a wavelength-selective light-shielding element capable of blocking circularly-polarized light beams rotating in a specific direction among light beams whose wavelengths falling in a specific range, a light-shielding region is provided in a portion of a transparent substrate, wherein the light-shielding region permits passage of first circularly-polarized light rotating in a first direction regardless of a wavelength of the first circularly-polarized light and blocks second circularly-polarized light beams whose wavelengths falling within a predetermined range, among second circularly-polarized light beams rotating in the second direction, to thus permit passage of the second circularly-polarized light beams falling outside the predetermined range.

Abstract: An information reproducing apparatus has a light source for generating linearly polarized light, a medium having linear marks disposed in overlapping relation to one another, and an optical head disposed between the light source and the medium and having a fine aperture. A polarized light control portion in the light source controls the linearly polarized light to pass through the fine aperture of the optical head to generate near-field light having a preselected polarization direction and to irradiate the linear marks of the medium with the near-field light so that the preselected polarization direction of the near-field light is orthogonal to a longitudinal axis of each of the linear marks. A detector detects light scattered by the linear mark irradiated with the near-field light.

Abstract: It is provided an optical head device which includes: a light source; an objective lens, configured to converge light emitted from the light source to an information recording surface of an optical disk; a beam splitter, configured to deflect returned light reflected by the optical disk into an optical path which is different from an optical path of the light emitted from the light source; a photo detector, configured to detect the returned light deflected by the beam splitter; and a depolarizing element, disposed on an optical path between the beam splitter and the photo detector, and configured to cause the returned light to transmit through while reducing a degree of polarization of the returned light.

Abstract: A method of forming a passivation layer over a ferroelectric layer of a ferroelectric media comprises introducing the ferroelectric layer to a plasma comprising one of oxygen, oxygen-helium, and oxygen-nitrogen-helium, etching a surface of the ferroelectric layer, forming one of a substantially oxygen enriched layer and a substantially hydroxyl enriched layer at the surface of the ferroelectric layer, introducing the ferroelectric layer to an environment comprising substantially nitrogen, and maintaining the ferroelectric layer within the environment so that nitrogen enriches the substantially oxygen enriched layer to form a passivation layer.

Abstract: An optical head includes semiconductor lasers for 455 nm, 655 nm, and 785 nm bands; a polarization change element and a polarizing beam splitter for luminous flux with a wavelength of 455 nm band, a first collimation lens for converting luminous flux having passed through the polarizing beam splitter into parallel flux, a first quarter-wave plate, a BD objective for focusing the flux onto a signal recording surface of BD, a first photo-detector for receiving light reflected by BD, a composite prism for reflecting flux reflected by the splitter and transmitting most of flux from the lasers for 655 nm and 785 nm bands, a second collimation lens for converting flux emitted from the composite lens into parallel flux, a second quarter-wave plate, an objective compatible with HD DVD, DVD, and CD; and a second photo-detector for receiving light reflected by HD DVD, DVD, and CD.

Abstract: An optical system capable of selectively processing CD, DVD and holographic digital data is provided. The system includes a beam generation unit providing a linearly polarized light beam; a beam splitter for respectively reflecting and transmitting a first and a second linearly polarized light beam component; an optical sensor; a first beam path through which the first linearly polarized light beam component propagates to serve as a reference beam for the holographic digital data; and a second beam path for accepting the second linearly polarized light beam component, the second light beam component serving as a beam source for reproducing the CD and DVD digital data, wherein a beam carrying digital data reproduced from any one of CD, DVD and holographic storage medium propagates along the second beam path and is reflected by the beam splitter toward the optical sensor.

Abstract: An optical pickup includes a laser light source, an objective lens which focuses light emitted from the laser light source on an optical information storing medium, an optical path changer which changes a proceeding path of the light emitted from the laser light source, a polarization changer which changes the polarization of an incident light to make the polarization of light reflected by the optical information storing medium and reentering the laser light source different from that of the light emitted from the laser light source, so that noise generated due to interference by the light reflected by the optical information storing medium and reentering the laser light source is reduced, and a photodetector which receives incident light reflected by the optical information storing medium and sequentially passing through the objective lens and the optical path changer and detects an information signal and/or an error signal.

Abstract: The present invention can simplify the configuration of a polarization adjustment plate. According to the present invention, the crystal axis of the polarization adjustment wavelength plate 32 is so arranged as to be turned up from the X-Y plane being an orthogonal plane with respect to the optical axis 40a, and the wavelength dependence which the crystal material is originally provided with is largely expressed, and further the thickness “ta” with respect to the optical axis 40a is set up such that the phase difference ? to be brought about at the beam center becomes low from 360°+180°=540° being a desired design value to irradiate the optical beam as the P-polarization by a predetermined difference value or 60°.

Abstract: An optical information reproducing method of the present invention is used for an optical recording medium. The optical recording medium includes a recording layer containing information and a mask layer that is located close to the recording layer and includes a nonlinear optical material whose optical properties are changed in accordance with incident light intensity. The method includes irradiating the optical recording medium with convergent light that is polarized in a first direction and dividing reflected light from the optical recording medium into a first polarized component that is polarized in the first direction and a second polarized component that is polarized in a second direction perpendicular to the first direction. The second polarized component is used to detect a reproduction signal.

Abstract: A semiconductor laser device has a semiconductor laser and a polarizing diffraction grating that is arranged ahead of the semiconductor laser. A reflected light from an optical recording medium is diffracted by the polarizing diffraction grating according to the polarization direction of the reflected light. The reflected light is thereby deviated from the direction toward the semiconductor laser to prevent the reflected light from returning to the semiconductor laser.

Abstract: An optical head device including a phase correcting element having an anisotropic optical medium sandwiched between a pair of substrates. The paired substrates have surfaces provided with electrodes for voltage application to the anisotropic optical medium. One electrode on at least one of the substrates has two or more power supply electrodes provided thereon at different positions, thereby providing different voltages to the respective power supply electrodes. The phase correcting element is provided between a collimating lens and a quarter wave plate in the optical head device.

Abstract: An optical recording medium, an optical recording and reproducing method, and an apparatus that can record and reproduce multilevel information at a high density and with a high S/N ratio. Recording light emitted from a light source is collimated by a collimation lens and introduced into a polarization rotary device. Recording light transmitted by the polarization rotary device is focused by an objective lens onto an optical recording medium. In response, a photo-induced birefringence is recorded on the optical recording medium. Multilevel recording is performed by controlling a voltage applied to the polarization rotary device to change a polarization angle ? of recording light. Reproduction is performed by detecting light reflected from the optical recording medium with an analyzer and a detector.

Abstract: A light orientation film and a liquid crystal thin film are formed adjacent to each other. Light is irradiated to the light orientation film and the liquid crystal thin film, so as to cause the light orientation film to be orientated while viscosity of the liquid crystal thin film is lowered by a temperature increase by the light irradiation, so that an intermolecular force on the boundary between the light orientation film and the liquid crystal thin film causes the liquid crystal molecules in the liquid crystal thin film to the orientation of the light orientation film. By this orientation of the liquid crystal molecules, recording information is maintained. Thus, it is possible to realize a sufficient signal amount while using the light orientation film as well as to obtain a thermal stability and a stability against light irradiation.

Abstract: A light emitted from a light source (11) or a return light from a magneto-optical discs (7a, 7b, 7c or 7d) is transmitted by a polarization maintaining optical fibers (15a, 15b, 15c or 15d). Phase difference generators (16a, 16b, 16c and 16d) are disposed in optical paths, respectively, for these light beams to generate a phase difference which is used to cancel, or multiply by an integer multiple of &pgr;, a phase difference between field vibration components, raised in the light due to the birefringence of the polarization maintaining optical fiber (15a, 15b, 15c or 15d) when the light is propagated through the latter.

Abstract: The inventive data memory (1) has an optically writeable and readable information carrier, which has a polymer film (11) whose refractive index can be locally altered by heating. An absorber is assigned to the polymer film (11) and is disposed for at least partially absorbing a write beam and for transferring, in an at least partially local manner, the heat generated thereby to the polymer film (11). The absorber is oriented in order to preferably absorb light with a polarization direction that is matched to the orientation of the absorber.

Abstract: The present invention includes an optical system to control and optimize molecular reorientation for information storage. A preferred embodiment of the invention utilizes light sources emitting at wavelengths centered on or around the absorption bands of the storage medium. The light can be selectively polarized to control orientation of molecular components of organic material to provide non-volatile storage of large amounts of information. This provides an alternative to magnetic, electric, magneto-optical, or electro-optical methods which are complex and expensive. The all-optical holographic method in accordance with the present invention provides a storage system with extremely high memory capacity. In accordance with another aspect of the present invention, a system for optically storing and retrieving data includes optically recording (writing) and retrieving (reading) with the same wavelength beam, for example, without additional conditions such as an electric or magnetic field.

Abstract: A method for reproducing write-once information from an optical disk. The disk includes a disk substrate and a recording layer on the disk substrate, the recording layer including a magnetic film with a magnetic anisotropy in a direction perpendicular to a surface of the magnetic film. Write-once information formed by first recording areas and second recording areas is stored in a pre-determined portion of said recording layer, the first and second recording areas having different magnetic anisotropies in a direction perpendicular to a surface of the magnetic film. The method includes irradiating linearly polarized laser light onto said pre-determined portion, and detecting a rotational change in a polarization orientation of light reflected from the optical disk or light transmitted through the optical disk, the rotational change being caused depending on which of the first recording area and the second recording area is irradiated with the linearly polarized laser light.

Abstract: The present invention provides an optical recording method, optical recording apparatus, optical reading method, and optical reading apparatus which are capable of high density recording an d high speed recording, and high speed reading. In recording, a recording light comprising a plurality of polarization distributions corresponding to the data information; is generated, and irradiated onto an optical recording medium to thereby record a plurality of polarization distributions of the recording light on the optical recording medium as photo-induced birefringence. In reading, a reading light having a uniform polarization distribution is irradiated onto the recording medium in which the data information has been recorded previously, and the polarization distribution of the transmitted light or reflected light in the optical recording medium is read as the polarization distribution of the reproducing light.

Abstract: An optical recording film in the form of a monomolecular layer, includes chemisorptive molecules that are chemically bonded by covalent bonding to a surface of a substrate. The optical recording film has the property that, when irradiated with polarized light, a long axis orientation of the chemisorptive molecules is changed to a direction in which the polarized light is irradiated. A reflective film may be formed on the substrate surface. For the chemisorptive molecules it is possible to use CH3—COO—C6H4—(CH2)6—SiCl3, for example. The molecules undergo a dehydrochlorination with active hydrogen in the base material surface, and are chemically bonded to the base material surface by covalent bonding. Thus, an erasable or a write-once optical recording medium of high density can be provided by chemisorption without necessitating vacuum vapor deposition to form the recording layer.

Abstract: The invention provides a transmission apparatus, a recording apparatus, a transmission and reception apparatus, a transmission method, a recording method and a transmission and reception method by which data can be communicated between different apparatus over a single data bus in accordance with a first communication method wherein data can be transmitted and/or received periodically and a second communication method wherein data can be transmitted and/or received asynchronously.

Abstract: An optical disc drive includes a laser diode 21 which oscillates in multimiode, a first plane-of-polarization preserving fiber 33, and a second plane-of-polarization preserving fiber 36. The first plane-of-polarization preserving fiber 33 and second plane-of-polarization preserving fiber 36 form an optical path for transmitting the laser beam irradiated from the laser diode 21, and variation of polarization state which arises due to the transmission of the laser beam by one of the plane-of-polarization preserving fibers is compensated by the other of the plane-of-polarization preserving fibers. Thus, the beam can be transmitted with its polarization state maintained.

Abstract: An optical storage medium of the present invention enables storage of data with high precision at high speed, and rewriting of data at high speed without an erasing process. Optical storage, reading and retrieving methods and optical storage, reading, and retrieving apparatuses using the medium are also provided. The optical storage medium has at least a polarization-sensitive member having the photo-induced birefringence property, such as a member made of polyester polymer having cyanoazobenzene as a side chain. The above apparatuses have spatial light modulator capable of modulating polarization. The modulator provides information of bit of two-dimensional data to each corresponding pixel by application or non-application of a voltage, and modulates the polarization of the beam incident on each pixel. Thereby, a signal beam transmitted through the spatial light modulator having a spatial polarization modulation corresponding to the two-dimensional data is obtained.

Abstract: This invention relates to a DVD reading-writing pickup head employing multiple wavelengths for data access on an optical record medium. With the configuration of the pickup head of the present invention, the number of the used optical elements is minimized. The pickup head of the present invention includes a cemented birefringent prism, a plurality of objective lenses, quarter-wavelength plates and laser sources and a photo detector. The cemented birefringent prism is used to refract the laser beams generated by the laser sources into an incident branch and split the laser beams and a reflected branch reflected from the optical record medium.

Abstract: Disclosed is an optical disc apparatus compatible with both ROM type and RAM type optical discs having high density and large capacity. An optical disc apparatus includes: a disc control device including an optical disc (a magneto-optical disc), a spindle motor for rotating the optical disc, an objective lens for forming a light spot on the optical disc, and a control drive device which controls and drives the objective lens in the tracking direction of the optical disc, a semiconductor laser serving as a light source, a signal light transfer having a polarization-preserving optical fiber for guiding output light from the semiconductor laser to the objective lens, ¼ wave plates provided in optical paths on both sides of the polarization-preserving optical fiber, and signal detecting devices (polarization beam splitter and photo detectors) for detecting a servo signal, etc. from the reflected light from the optical disc.

Abstract: This invention concerns a reading-writing pickup head for data access on optical record media. The pickup head of the present invention includes a birefringent prism and a quarter-wave plate where the birefringent prism is made of double-refraction material with different refraction indices on different polarizations, and it is used to split the incident and reflection beams of the pickup head. According to the present invention, the prism and the polarized beam splitter of a pickup head of the related art are replaced with the birefringent prism. Consequently, the number of optical elements of the pickup head according to the present invention is reduced.

Abstract: A compact optical pickup head which doesn't utilize a holographic optical element is disclosed. A birefringent prism and a quarter-wave plate are disposed in the optical path of the compact pickup head. The birefringent prism is consisted of two crystals made from a birefringent material, and having their optical axes perpendicular to each other. Therefore, the laser source beam will not be refracted when passing through the birefringent prism or will be refracted to a direction differing from the returning beam), while the returning beam is refracted by the birefringent prism to the photo detector. The power of laser ray is fully utilized to increase the reliability of signal transformation. A higher optical signal can be obtained, and the interference of returning beam to the source beam is also be prevented.

Abstract: A multilayer resonance device of the invention includes 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, having a thickness disaccording with the thickness regularity and disposed between the regularly stacked layers. Thus, the multilayer resonance device can attain a large Faraday rotation angle, a large magneto-optical effect, and a practical total layer thickness.

Abstract: A light source is provided for emitting a first beam having a far-field pattern of an elliptic shape. The first beam is a linearly polarized light having a first polarizing direction in a major axis of the elliptic shape. A half-wave plate is provided for rotating the polarizing direction of the first beam 90 degrees, thereby changing the first beam to a second beam. A beam splitter is provided for changing the elliptic shape of the second beam into a circular shape. The beam splitter is arranged to transmit the second beam and to reflect a third beam having a polarizing direction different from that of the second beam by 90 degrees. A quarter-wave plate is provided for transmitting the second beam from the beam splitter to apply it to an optical disc, and for changing the second beam reflected from the optical disc into the third beam. The third beam reflected from the beam splitter is applied to a photodetector.