Abstract: Novel optical modulators and other high performance Faraday-Stark magneto-optoelectronic devices (MOE's) are disclosed that allow electrical adjusting of the polarization (or other optical properties) of an excitation light at high modulation bandwidth and deep modulation depths through the Faraday-Stark effect. The high performance Faraday-Stark magneto-optoelectronic devices of the present invention include a Faraday-Stark cell having at least one quantum well formed in a semiconductor or other material defining transition energies and wavefunction overlaps that correspond to the presence and/or magnitude of magnetic and electric fields that may be present to the quantum wells of the cell.

Abstract: A magneto-optic element is employed to create an optical attenuator, an optical modulator and a magnetic field strength sensor. The magneto-optic element exhibits a multiple domain structure in a state where no magnetic field is applied, wherein magnetization components in adjacent domains of the element along a direction in which a light beam travels are different from one another. The optical attenuator further includes apparatus for applying a magnetic field of variable strength to the magneto-optic element. The optical modulator further includes apparatus for applying a modulated magnetic field to the magneto-optic element. The magnetic field strength sensor operates by placing the magneto-optic element in the vicinity of an object to be measured. A light beam is directed from an input optical fiber onto the magneto-optic element and the element diffracts the light beam. A portion of the light beam exiting the element impinges on a reflector and is received by a second optical fiber.

Abstract: A recording medium includes a transparent substrate and a recording layer formed thereon for recording information, and a component made of material with a large loss factor, such as butyl rubber, bond magnet, etc. By suppressing recording medium vibration resonance from a recording and reproducing device, an improved frequency characteristic of a linear motor can be achieved, thereby enabling high access speed. Preferably, the large-loss material also provides a directional magnetic field which facilitates magneto-optical rewriting on the recording layer.

Abstract: An optical isolator is disclosed that is particularly useful in the visible, infrared, and near-infrared portions of the electromagnetic spectrum. The rotator portion of the isolator produces a highly uniform magnetic intensity across its clear aperture. The optical isolator comprises a Faraday rotator that defines an optical axis, a respective polarizer on each end of the Faraday rotator and positioned on the optical axis, and a housing containing the Faraday rotator and the polarizers. The Faraday rotator comprises an optical rotator rod that defines the optical axis and a magnet assembly surrounding the optical rotator rod. The magnet assembly comprises eight trapezoidal cross section magnet sections arranged in a first group of four and a second group of four.

Abstract: A polarization plane switch comprising a Faraday rotator made of an iron-containing garnet single-crystal film and magnetic field applying devices capable of reversing a magnetic field to be applied to the Faraday rotator. The polarization plane switch has a structure in which magnetization of part of the Faraday rotator is unsaturated and that of the remaining portion of it is saturated when a magnetic field is applied to the Faraday rotator by the magnetic field applying device, and a light beam passes through the magnetically saturated portion almost vertically to the film surface. As the above Faraday rotator, it is the most preferable to use a Faraday rotator made of Bi-substituted iron garnet single crystal formed by liquid-phase epitaxy and having a compensation temperature, and thermally treated under the top condition at a temperature between 1,120.degree. and 1,180.degree. C. for 7 hours or less.

Abstract: A magneto-optic element is employed to create an optical attenuator and an optical modulator. The magneto-optic element exhibits a multiple domain structure in a state where no magnetic field is applied, wherein magnetization components in adjacent domains of the element along a direction in which a light beam travels are different from one another. The optical attenuator further includes apparatus for applying a magnetic field of variable strength to the magneto-optic element. The optical modulator further includes apparatus for applying a modulated magnetic field to the magneto-optic element. In both devices, a light beam is directed from an input optical fiber onto the magneto-optic element. The element diffracts the light beam. A portion of the light beam exiting the element impinges on a reflector and is received by a second optical fiber. In the optical attenuator, that portion of light is attenuated with respect to the light in the input optical fiber.

Abstract: Disclosed herein is a multi-pole magnetic geometry for a multi-oscillator ring laser gyroscope. Multi-pole magnetic geometry configurations are disclosed which are useful for providing Faraday rotation where the multi-oscillator uses a Faraday rotator and high magnetic field effect where the nature of the multi-oscillator ring laser gyroscope is of split gain configuration. The multi-post magnetic geometry includes a plurality of top or bottom loaded diametrically opposed north and south pole axially directed magnets which are positioned substantially transverse to the optical pathway but suitable for providing axially directed magnetic fields to portions of the optical pathway only where desired. The multi-pole magnetic geometry disclosed herein substantially produces a magnetic flux that is restricted in its position to localized portions of the optical pathway with low far field effects.

Abstract: A reflection type magnetooptic sensor head is disclosed. The respective structural elements are aligned following a light source in the order of a light inputting/outputting path, polarizer, Faraday rotator, and reflecting mirror. The Faraday rotator is made of a (111) bismuth-substituted iron garnet single crystal film having [111] axis at an angle of 5-60 degrees with an axis normal to the film surface. The reflecting mirror is positioned such that a light incident upon the reflecting mirror is substantially normal to the surface of the reflecting mirror.

Abstract: An optical device which optically connects a first and a second optical fiber with an optical path provided therebetween and has two or more functions including the function of an optical isolator. A beam of parallel rays obtained by having a beam from an excitation end of a first optical fiber collimated by a lens is passed through a double refraction element, a magnetooptic element, and a double refraction element in order of mention and converged by a lens to be introduced to a second optical fiber through its excitation end, while a beam from the second optical fiber is not coupled to the first optical fiber. Meanwhile, a beam from an excitation port is coupled to the first optical fiber. The optical device is suitable for use in an optical amplification system and a two-way optical transmission system.

Abstract: An insertion device for extracting polarized electromagnetic energy from a beam of particles is disclosed. The insertion device includes four linear arrays of magnets which are aligned with the particle beam. The magnetic field strength to which the particles are subjected is adjusted by altering the relative alignment of the arrays in a direction parallel to that of the particle beam. Both the energy and polarization of the extracted energy may be varied by moving the relevant arrays parallel to the beam direction. The present invention requires a substantially simpler and more economical superstructure than insertion devices in which the magnetic field strength is altered by changing the gap between arrays of magnets.

Abstract: An optical isolator comprises two birefringent plates one of which separates two light components whose planes of polarization are perpendicular to each other to make the two light components spatially separate between the two birefringent plates and pass through two separate optical paths and the other of which thereafter combines the two separate light components, two Faraday rotators disposed between the two birefringent plates and having a Faraday rotation angle of approximately 45 degrees, a polarizer disposed between the two Faraday rotators and having a predetermined polarized-light transmitting angle, and a magnetic field device for applying an external magnetic field to the two separate optical paths in the two Faraday rotators to magnetize respective regions near the two optical paths in each of the rotators in opposite magnetization directions to each other.

Abstract: An optical beam steering device for use in a single-aperture laser transceiver system provides deflection of the transmitted and received beams in two planes, while maintaining the distinctive identities of each channel respective to their polarizations. The invention utilizes four single-dimensional beam deflecting devices, two for each orthogonal linear polarization of the two transceiver channels, one of these for each steering axis. In addition, a 90.degree. polarization rotator and a quarter-wave plate are included in the arrangement of beam deflecting devices to satisfy the polarization requirements of these devices and of the transceiver channels.

Abstract: In a polarization-state converting apparatus for use as an optical isolator, an optical modulator and the like, there are provided a waveguide including a magnetic semiconductor, a device for applying a magnetic field to the waveguide in a first predetermined direction, a device for applying an electric field to the waveguide in a second predetermined direction, and a mode conversion is caused via electrooptic and magnetooptic effects due to the electric and magnetic fields to change the polarization state of light propagating through the waveguide. When used as an optical isolator, the optical isolation is performed to compensate for degradation of the mode conversion rate due to a phase mismatch between light incident upon the waveguide and light emerging from the waveguide.

Abstract: A haze-free light modulating polymer dispersed liquid crystal (PDLC) material is disclosed which comprises a polymer which is birefringent and possesses anisotropic optical properties similar to those of the dispersed liquid crystal such that the PDLC material in its transparent state exhibits a refractive index that is matched for all directions of incident light providing for an optically clear, scatter-free film for all angles of view. Electrooptic light shutters are possible from this material which are transparent in the field OFF-state and opaque in the field ON-state or vice versa, depending upon the liquid crystal phase structure and configuration of the light shutter device.

Abstract: First and second beam splitters are arranged on the optical path of a light beam emerging from a recording surface, and such that the phases and amplitudes of the respective polarized light components of a light beam incident thereon are changed to equal extends. As a result of this arrangement, the state of polarization beam of the light beam emerging from the recording surface is maintained when a light beam is outputted through the two beam splitters. Stable reproduction signals and servo control signals for focusing, tracking, and the like can be reliably supplied by utilizing an apparatus of this invention.

Abstract: Apparatus for reading out information magneto-optically recorded in a magnetic layer comprises a single, polarization-preserving optical fiber for transmitting plane-polarized readout radiation from a source to the recording layer, as well as for transmitting such radiation, upon being reflected by the recording layer, toward a pair of photodetectors for the differential detection of the Kerr rotation angles (.+-..THETA..sub.k) produced by the up/down orientation of the vertically oriented magnetic domain in the recording layer. Optical feedback of the reflected readout radiation to the readout source is minimized by the provision of a pair of polarization beam-splitters having a 45 degree magneto-optic polarization-rotator (e.g. a Faraday rotator) positioned therebetween. The polarization beam-splitters and retardation plate are positioned in the optical path between the readout source and the optical fiber.

Abstract: An electron wave interference device controlled by a light is disclosed. The electron wave interference device includes a first channel to propagate an electron wave, a second channel arranged with an interval from the first channel for propagating an electron wave, and an magnetic field application device for applying a magnetic field into the first and second channels and a region sandwiched by those channels so as to traverse them. The electron waves which are respectively propagated in the first and second channels mutually interfere, and when the light is irradiated to those channels, a distance between peaks of wave functions of the electron waves which propagate in the channels is changed, so that a phase difference occurs in the electron waves.

Abstract: An improvement in a method of rotating the plane of polarization of polarized light in a Faraday rotator, having an optical element which includes a ferromagnetic material, which comprises varying the strength of the magnetic field generated along the optical axis of the optical element in response to changes in the wavelength of the polarized light. The magnet employed in the Faraday rotator may be at least one permanent magnet or an electromagnet. Preferred optical elements are made of disc having a gadolinium-gallium-garnet (GGG) or large lattice constant (LLC) substrate, and the substrate is coated with an oxygen--and iron--containing film.

Abstract: An optical sensor excellent in reliability and mass producibility and low in cost, by forming a magnetic optical crystal, polarizer and analyzer monolithically on the same substrate.

Abstract: A Faraday rotator having a first, or central magnet, and first and second tuning magnets a opposite ends of the central magnet. The central magnet and the tuning magnets are of opposite polarities. The central magnet surrounds a first optical element having a positive or negative Verdet constant, and the tuning magnets surround second and third optical elements, respectively. The second and third optical elements each have a Verdet constant of a sign opposite that of the first optical element. Such Faraday rotators require smaller magnet assemblies than Faraday rotators having just one optical element surrounded by the central magnet. There is also provided a Faraday rotator having at least two magnets wherein each magnet of any one pair of contiguous magnets generates a magnetic field in a direction opposite that generated by the other of the any one pair of contiguous magnets. The optical elements surrounded by these magnets have oppositely signed Verdet constants.