Abstract: As will be described in more detail hereinafter, there are disclosed herein high performance optical circulators and an associated method. The improvement in these circulators comprises an arrangement along the length of the main body for performing a predetermined sequence of optical operations including at least three non-reciprocal polarization rotation steps which are separated from one another by other optical operations (a) on a first light signal as the first light signal passes in a forward direction from a first port to a second port and (b) on a second light signal as the second light signal passes in a rearward direction from the second port to a third port such that a substantial portion of the first light signal exits from the second port and a substantial portion of the second light signal exits from the third port and so that the first and third ports are physically isolated with respect to one another at the first end.

Abstract: A Faraday rotator is formed of a bismuth-substituted iron garnet single crystal film on which an antireflection film is formed. The antireflection film includes first, second, and third layers. The first layer is a layer of silicon dioxide. The second layer is a layer of tantalum pentoxide. The third layer is a layer of silicon dioxide. The first, second, and third layers are formed in this order from the atmosphere side on the bismuth-substituted iron garnet single crystal film. The antireflection film may be formed on both of opposing surfaces of the single crystal film.

Abstract: An optical isolator has a high ratio of the quantity of signals S to that of noises N (S/N ratio) and can be miniaturized such a size that it can easily be incorporated into a laser module. The optical isolator 1 according to the present invention is one to be connected to a semiconductor laser 11 having a linear polarization plane and comprises a Faraday's rotator 5 and a magnetic material 4 for establishing a magnetic field around the rotor on the light-incident side of the isolator and an optical material 6 for polarization on the light-outputting side thereof.

Abstract: An optical isolator (2) comprising two polariser means (10,12), two input/output ports (4,6) formed respectively on the polariser means (10,12), and optical rotator means (14,18) disposed between the polariser means (10,12), the optical rotator means (14,18) including Faraday rotator means (14) and being selectively configured so the isolator (2) performs one of a plurality of isolator functions.

Abstract: A magnetostatic wave device comprising a magnetic garnet single crystalline film having a general formula of R.sub.3-x Ca.sub.x Ma.sub.5-2y+x Zr.sub.y Mb.sub.y-x O.sub.12 wherein R is at least one of Y, La, Bi, Gd, Lu and Sc, and Ma is at least one of Fe, Ga and Al, while Fe is present as an essential component, and Mb is at least one of Mg and Mn, and wherein the conditions of 0.ltoreq.x.ltoreq.1, 0.1.ltoreq.y.ltoreq.1, and x.ltoreq.y are satisfied.

Abstract: A micromechanical optical modulator having a linear response in reflectivity, as a function of applied bias, and a method of operating and making same, are disclosed. The modulator consists of a movable layer suspended over a substrate. A gap is defined between the movable layer and the substrate. As the movable layer moves, the gap changes size, resulting in a change in modulator reflectivity. In operation, the movable layer moves within a linear operating regime under the action of an applied voltage, which is the sum of a constant bias and a signal from an analog source. A substantially linear operating characteristic, i.e., reflectivity versus applied voltage is obtained within the linear operating regime by properly selecting the size of the gap in the absence of the applied voltage and the range in the applied voltage.

Abstract: An optical isolator device is provided which is free from polarization dispersion. The optical isolator device presents an optical path which is equidistant for both an ordinary ray and an extraordinary ray. The optical isolator device of the present invention comprises a first and second optical isolator, each of identical thickness and each comprising a birefringent for separating an ordinary ray and an extraordinary ray, a polarization rotator for rotating the plane of polarization of these rays and a birefringent for continuing the ordinary ray and the extraordinary ray. In an embodiment of the present invention, an optical isolator device comprises two optical isolators in series, each comprising a first birefringent element for separating an input beam into an ordinary ray and an extraordinary ray, a polarization rotor for rotating the planes of polarization of the ordinary and extraordinary rays by (2m .+-.1/2).times.

Abstract: An optical isolator and circular polarizer are used in combination to optically isolate specular and diffuse reflections which result when a forward traveling radiation beam encounters an optical or non-optical boundary surface. The forward traveling radiation beam is linearly polarized with a linear polarizer such that its plane of linear polarization is aligned with a first polarization axis, then the axis of linear polarization is rotated to a second polarization axis with a polarization rotator and finally the linearly polarized forward traveling beam is circularly polarized with a quarter wave retarder.

Abstract: A polarization-independent optical isolator having a structure in which polarization dispersion is virtually eliminated by selecting the thickness and optical axis orientations of birefringent crystalline plates used in the isolator. The optical isolator of the present invention employs a combination of birefringent crystalline plates wherein the optical axis orientation of at least one birefringent crystalline plate in the optical isolator is different from the optical axis orientation of the remaining birefringent crystalline plates, and the polarization mode dispersion, which is induced when the beam propagates through the birefringent crystalline plate having a different optical axis orientation, is equal to the dispersion rate of the polarization mode dispersion attributable to the remaining birefringent crystalline plates and in a mutually inverse direction.

Abstract: An optical isolator includes two polarizers two input/output ports formed respectively on the two polarizers and an optical rotator disposed between the two polarizers, the optical rotator including a Faraday rotator and a reciprocal optical rotator being selectively configured so the isolator performs one of a plurality of isolator functions.

Abstract: An optical isolator, which is small in size, light in weight and simple in manufacture, includes a Faraday element (1). The optical isolator also includes polarization films (2a, 2b) formed on a light incident surface and light emitting surface of the Faraday element. The Faraday element rotates a polarization plane of incident light by an angle approximately equal to 45.degree.. The optical isolator also includes a magnetic field applying mechanism (3) for applying a magnetic field to the Faraday element. Each of the polarization films (2a, 2b) includes a thin film made of a conductive material. The polarization films form unidirectional grating with an interval not greater than one tenth of the wavelength of light. One of the polarization films (2b) formed on the light emitting surface makes, in a plane perpendicular to an optical axis, an angle with respect to the other polarization film (2a) formed on the light incident surface, the angle which is approximately equal to 45.degree.

Abstract: A vertical modulator with a dual mode distributed Bragg reflection (DBR), includes a pair of integrated elements using different wavelengths to provide functions of logical operation, data switching and wavelength conversion. The optical device includes a first optical structure operating at a first wavelength (.lambda..sub.1) and a second optical structure operating at a second wavelength (.lambda..sub.2). The first and second optical structures are formed over a semiconductor substrate. The first optical structure, which operates at the first wavelength (.lambda..sub.1), transmits its data to the second optical structure so that data corresponding to the second wavelength (.lambda..sub.2) can be output. Since the wavelength of input light is different from the wavelength of output light, the optical device serves as a modulator which performs a logic operation and switching function while carrying out wavelength conversion.

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 Faraday rotator which comprises, in combination, a garnet material of an atomic ratio compositionBi.sub.x P.sub.y Q.sub.3-x-y Fe.sub.5-w M.sub.w O.sub.12in which P is one or more elements chosen from among Y, La, Sm, Eu, Tm, Yb, and Lu, Q is one or more elements chosen from among Gd, Tb, Dy, Ho, and Er, M is one or more nonmagnetic elements that can substitute for Fe, and 0.7.ltoreq.x.ltoreq.2.0, 0.5.ltoreq.y.ltoreq.2.3, 0.ltoreq.3-x-y.ltoreq.1, and 0..ltoreq.w.ltoreq.1.0, and a magnet for applying a magnetic field smaller than the saturation magnetic field to said material. Preferably, the value w ranges from 0.2 to 0.7, and a Faraday rotator especially excellent is one using a garnet material in which M.sub.w is represented by A.sub.k D.sub.l where A is an element to be substituted for the site a of the garnet, selected, e.g., from among Sc, In, etc., D is an element to be substituted for the site d of the garnet, selected, e.g., from among Ga, Al etc., and 0.ltoreq.k<0.1, 0.2.ltoreq.l.ltoreq.0.

Abstract: Optical isolator, circulator, switch or the like, including a Faraday rotator to which a magnetic field is applied which is oriented along the direction of propagation of light and which is arranged between a preceding polarization filter and a succeeding polarization filter whose planes of polarization enclose an angle with respect to each other such that light can only traverse in one direction, the Faraday rotator having different propagation constants .beta..sub.TE and .beta..sub.TM in a TE plane and a TM plane, respectively. The elaborate technique for adapting the propagation constants of the TE wave and the TM wave is mitigated in that the TE plane of the Faraday rotator is aligned in such a way that it extends between the planes of polarization of the polarization filters.

Abstract: A surface magnetostatic wave device includes an Fe-containing garnet single crystal film grown on a gadolinium gallium garnet substrate. The crystallographic plane azimuth of the gadolinium gallium garnet substrate can be one of a (110) plane, a (100) plane, and a (211) plane. The device achieves both a reduced saturation magnetization and a reduced anisotropic magnetic field to thereby minimize the lowest frequency in the propagation band.

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: Disclosed is a material for a magneto-optical element, which is made of magnetic garnet single crystals being wide in a band width in a 1310 nm band and thereby being capable of coping with the wavelength multiplex communication at the wavelength band, and a Faraday rotator using the same. The material for a magneto-optical element is made of a magnetic garnet having a composition formula expressed by R.sub.3-y-x Sm.sub.y Bi.sub.x Fe.sub.5 O.sub.12, where R is one kind of rare earth elements including yttrium (Y), and "x" and "y" are constants defined by 0.3.ltoreq.x.ltoreq.1.9 and 0.4.ltoreq.y.ltoreq.2.7, the magnetic garnet being formed on a non-magnetic substrate by liquid-phase epitaxial growth. R is preferably one of Y, La, Sm and Lu. The Faraday rotator, which is used in a wavelength range of from 1250 to 1370 nm, is formed by superposing a film A made of LPE magnetic garnet single crystals expressed by a composition formula of R1.sub.3-x Bi.sub.x Fe.sub.5-z Z.sub.z O.sub.

Abstract: A Faraday rotator in which a portion of a rare-earth iron garnet single crystal film is exposed to a localized magnetic field to control hysteresis. In one embodiment, the field is applied by a permanent magnet positioned on a part of the film. As a result, it is possible to fabricate Faraday effect optical switches and magneto-optical sensors using rare-earth iron garnet films having small saturated magnetic field intensities.

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 sensor system including a magnetooptic sensing element, a light source, at least one polarizer and at least one detector disposed about the sensing element. The sensing element has a first characteristic such that the sensing element provides a response to an applied external stress.

Abstract: A Faraday's rotator comprises a magnetic crystal which has a composition represented by the following compositional formula: (Tb.sub.1-(a+b+c+d) Ln.sup.1.sub.a Ln.sup.2.sub.b Bi.sub.c M.sup.1.sub.d).sub.3 (Fe.sub.1-e M.sup.2.sub.e).sub.5 O.sub.12, has a lattice constant of 12.383.+-.0.006 .ANG. and is grown through the liquid phase epitaxial growth technique. In the foregoing formula, Ln.sup.1 is at least one element selected from the group consisting of Yb, Lu and Tm; Ln.sup.2 is at least one member selected from the group consisting of rare earth elements except for Yb, Lu, Tm and Tb; M.sup.1 is at least one element selected from the group consisting of Ca, Mg and Sr; M.sup.2 is at least one element selected from the group consisting of Al, Ga, Ti, Si and Ge; 0.2.ltoreq.a.ltoreq.0.6, 0.ltoreq.b.ltoreq.0.3, 0 <c.ltoreq.0.16, 0<d.ltoreq.0.02 and 0<e.ltoreq.0.1. Another Faraday's rotator comprises a magnetic crystal having a composition represented by the following compositional formula: (Tb.sub.

Abstract: A thin transparent epitaxial layer of a magnetizable material (e.g. gallium ferrite) is deposited on a substrate of a dielectric transparent material (e.g. gadolinium gallium garnet). A mask made from an oxidizable material (e.g. silicon) deposited on the epitaxial layer covers pixels defining rows and columns and exposes the other areas on the epitaxial layer. The epitaxial layer is then annealed at a suitable temperature (e.g. 500.degree. C.) for a suitable time (e.g. 10 minutes) to oxidize the silicon and reduce the Fe atoms in the pixel areas beneath the mask to Fe.sup.++ ions. This causes the pixel areas beneath the mask to be more easily magnetizable than the other areas in the epitaxial layer. The mask is then removed and a first insulating layer is deposited on the epitaxial layer. A first plurality of windings is then deposited on the first insulated layer in insulating relationship to one another.

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 element for an optical isolator which is formed by alternately bonding together at least one flat plate-shaped Faraday rotator and two or more flat plate-shaped polarizers, the optical isolator element having an outer peripheral surface which is cut such that, when the outer peripheral surface is disposed parallel to an optical axis, incidence and emergence planes of the element are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis. The optical isolator element is accommodated in a cylindrical magnet having an inner peripheral surface of the same shape as the outer peripheral surface of the optical isolator element, thereby forming an optical isolator.

Abstract: At least one non-reciprocal rotation element is interposed between two adjacent walk off crystal members to form an optical isolator. Light in the forward direction is separated into two rays of linear polarizations where there is substantially no optical path length difference between the two rays. Light transmitted in the reverse direction is reduced. A conventional optical isolator which does not preserve optical path length difference is converted into one which does by adding a birefringent plate to compensate for the optical path length difference introduced by the conventional isolator. A pair of collimating lenses may be introduced between any pair of non-reciprocal rotation elements.

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 element for an optical isolator which is formed by alternately bonding together at least one flat plate-shaped Faraday rotator and two or more flat plate-shaped polarizers, the optical isolator element having an outer peripheral surface which is cut such that, when the outer peripheral surface is disposed parallel to an optical axis, incidence and emergence planes of the element are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis. The optical isolator element may be formed with a rectangular configuration in conformity to the arranged form of a plurality of laser active regions of a laser array.

Abstract: An optical isolator not dependent on the plane of polarization of an incident beam and does not allow the plane of polarization to change on the outgoing side. The optical isolator comprises a first parallel flat double refractive crystal substance; a first Faraday rotor for rotating the plane of polarization of a beam; a second parallel flat double refractive crystal substance; a second Faraday rotor for rotating the plane of polarization in a direction opposite to that in which said first Faraday rotor rotates the plane of polarization; a third parallel flat double refractive substance; a fourth parallel flat double refractive substance; and permanent magnets for magnetizing the Faraday rotor and second Faraday rotors. Since a pair of Faraday rotors for rotating the plane of polarization in opposite directions, the plane of polarization on the incident side does not change on the outgoing side.

Abstract: In an optical isolator device comprising a plurality of optical isolator elements each of which comprises a pair of polarizers and a magneto-optical element disposed between said polarizers, the optical isolator elements have element cutoff wavelength bands which are different from one another. The optical isolator elements are arranged in series with an optical axis in common. Each element cutoff wavelength band is defined by an element cutoff central wavelength for a return light beam. The optical isolator device has a device cutoff wavelength band for the return light beam that is defined by a device cutoff central wavelength. When the optical isolator elements are equal in number to two, both of the optical isolator elements have a common wavelength area where the element cutoff wavelength bands overlap each other.

Abstract: An optical filter device comprised of two parallel arrays of lenses. Each lens in the first array faces a lens in the second array to form a pixel. Lens pairs in a pixel are separated by the sum of their focal distances and include in their common focal surface a "smart" layer for modulating light passing through the focal surface. Preferred embodiments include car rear view mirrors, sunglasses, glasses for night driving, laser goggles, nuclear goggles, sun visors, sun shields, windshields, space suit helmet visors, optical instrument protection devices, window filters and energy conservation devices.

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: A compound semiconductor device and a process for manufacturing it is disclosed. The process comprises the steps of forming a first conduction type first clad layer, a first conduction type or second conduction type activated layer, a second conduction type second clad layer, and a second conduction type cap layer upon a first conduction type semiconductor substrate, forming a first conduction type electrode and a second conduction type electrode, and forming a rectangular pole shaped laser diode, a triangular pole shaped detecting photo-diode, and a triangular pole shaped receiving photo-diode by carrying out a single round of anisotropic etching. According to the present invention, the high density can be easily realized, so that the power consumption and the manufacturing cost can be saved.

Abstract: A spherical multicomponent optical isolator having a first spherical segment lensing region, including a base, a second spherical segment lensing region, including a base, a first polarizer attached to the base of the first segment lensing region, a second polarizer attached to the base of the second spherical segment lensing region and A Faraday rotator disposed between the first and second polarizers, wherein the combination of the first and second spherical segments, the first and second polarizers and the Faraday rotator forms the spherical optical isolator having a spherical outer surface.

Abstract: An optical isolator comprising an optical isolator unit having a structure depending on a plane of polarization of incident light, a first optical system for splitting the incident light into two polarized components for incidence on the optical isolator unit, and a second optical system for combining the two polarized components emerging from the optical isolator unit. The optical isolator can thus manifest an excellent effect of isolation without considering the plane of polarization of the incident light.

Abstract: In an optical isolator, first, second and third birefringent crystals shaped in a flat plate are arranged in order in a forward direction in which a light beam advances and formed in ratios 1:1:1 in thickness. One magneto-optical member is interposed between the first and second birefringent crystals and another magneto-optical member may be arbitrarily disposed between the second and third birefringent crystals. Since the birefringent crystals are equal in thickness, the optical isolator can be readily produced with a high accuracy without much labor.

Abstract: A reflective mode, magneto-optic spatial light modulator (MOSLM) device has planar electrical conductors which function both as optical mirror surfaces and as the address conductors for random access, selective switching of an associated individual pixel element which is formed from a magneto-optic material that exhibits magnetic domain characteristics, and further has a crossover portion of one of the reflective electrical conductors embedded in the magneto-optic device material at a nucleation region formed in the device material.

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 reflective mode, magneto-optic spatial light modulator (MOSLM) device has one or more pixel elements formed from a selected magneto-optic material with a respective pair of coincident current select electrical conductors associated with each pixel where at least one of the conductors is planar and thereby develops a reflector surface that reflects incident radiation, such as polarized light of an optical beam, which has passed at least through an associated pixel back through the magneto-optic material and resident single magnetic domain of the pixel.

Abstract: An optical isolator having a combination of rutile plates or other birefringent crystals and Faraday elements. This optical isolator includes, arranged in the stated order along an optical axis, a first birefringent crystal; a first Faraday element for rotating a plane of polarization 45.degree.; a second birefringent crystal having an optic axis rotated 45.degree. with respect to the first birefringent crystal, and a thickness .sqroot.2 times a thickness of the first birefringent crystal; a third birefringent crystal having an optic axis rotated 135.degree. with respect to the first birefringent crystal, and a thickness .sqroot.2 times the thickness of the first birefringent crystal; a second Faraday element for rotating the plane of polarization 45.degree.; and a fourth birefringent crystal having an optic axis rotated 180.degree. with respect to the first birefringent crystal, and a thickness equal to the thickness of the first birefringent crystal.

Abstract: The optical circulator according to the present invention comprises three birefringent crystal plates 22, 23, and 24; reciprocal and non-reciprocal rotators 25 of the first group inserted between birefringent crystal plates 22 and 23; reciprocal and non-reciprocal rotators 26 of the second group inserted between birefringent crystal plates 23 and 24; and more than two beam incoming and outgoing ports 27, 28, and 29. The rotating directions of the reciprocal and non-reciprocal rotators 25 of the first group are so set that the directions in which ordinary beam and extraordinary beam are separated on the birefringent crystal plates differ among birefringent crystal plate 23 and birefringent crystal plates 22 and 24, and the electric field vibration directions of the beams agree at birefringent crystal plate 23.

Abstract: The optical isolator of the present invention comprises a polarizer, a Farady rotator and an analyzer arranged in this order, wherein the Farady rotator has a garnet crystalline structure represented by the formula (Tb.sub.1-(a+b) Ln.sub.a Bi.sub.b).sub.3 (Fe.sub.1-c M.sub.c).sub.5 O.sub.12 wherein Ln represents at least one element selected from the group consisting of rare earth elements other than Tb; 0<a.ltoreq.0.6; 0<b .ltoreq.0.2; M represents at least one element selected from the group consisting of Al and Ga; and 0.ltoreq.c<0.1; or the formula (Tb.sub.1-(d+e+b) Ln.sub.d Eu.sub.e Bi.sub.b).sub.3 (Fe.sub.1-c M.sub.c).sub.5 O.sub.12 wherein Ln represents at least one element selected from the group consisting of rare earth elements other than Tb and Eu; 0<d<0.6; 0<e.ltoreq.0.2; 0<d+e.ltoreq.0.6; 0<b.ltoreq.0.2; M represents at least one element selected from the group consisting of Al and Ga; and O.ltoreq.C<0.1; or the formula (Y.sub.1-(a+b) Ln.sub.a Bi.sub.b).sub.3 (Fe.sub.

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 optical switch comprises a substrate, a lower cladding layer, a waveguide layer, and an upper cladding layer each formed of a semiconductor, and in which at least one of the three layers except the substrate has a quantum well structure at a quantum confined potential. The well plane of the quantum well structure is symmetrical with respect to the center position thereof, and varies in proportion to the square of the distance from the center position. If an electric field is applied perpendicular to the well plane, the respective changes in the absorption coefficient and refractive index in the vicinity of the absorption edge are influenced by absorption peak shifts attributable to both 1e-1hh and 1e-11h transitions. Thus, the optical switch operates in response to both TE and TM mode light without depending on polarization.

Abstract: An optical isolator having three or four birefringent crystals and two magneto-optic elements is disposed between two light waveguides to prevent reverse-directed light from returning to the light waveguide on the light-source side. Forward-directed light emitted from the light waveguide on the light-source side is allowed to properly enter into the other light waveguide, whereas the reverse-directed light returning reflectively toward the light waveguide on the light-source side is separated into two polarized component and undergoes polarization rotation while propagating in the optical isolator, to thereby advance out of the optical axis of the light-source side light waveguide.

Abstract: Apparatus according to the invention comprises a magneto-optic isolator. The isolator comprises a magneto-optic member that comprises a single crystal substrate and a single crystal garnet layer on the substrate. The garnet layer comprises a first and a second stratum. The composition of the former is chosen such that the lattice constant of the first stratum material is substantially equal to that of the substrate at a first temperature (e.g., room temperature), and is substantially larger than that of the substrate at a second temperature (e.g., the garnet growth temperature) that is higher than the first temperature. The composition of the second stratum is chosen such that the lattice constant of the second stratum is less than that of the substrate at the first temperature, and is less than that of the first stratum at the second temperature. Wafers according to the invention typically are less subject to fracture than analogous prior art wafers.

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.

Abstract: An optical isolator in which a mirror is arranged in the waveguide path to provide Fresnel reflection of the propagating light and change the light path direction by 90 degrees, the light path from the waveguide input plane to the mirror forms a first region in which magneto-optic-induced non-reciprocal mode conversion takes place, and the part of the light path from the mirror to the waveguide output plane forms a second region in which reciprocal mode conversion takes place, and mode selectors or polarizers are provided at the light input and output planes.

Abstract: A device for the direct visualization of surface and near surface cracks, voids, flows, discontinuities, etc. in a target material. A magnetic garnet epitaxial film is deposited on either side, or both sides, of a non-magnetic substrate. A reflective material is provided adjacent to the epitaxial film, and the substrate with its associated layers is placed over a sheet of current carrying material and this sheet is placed over the target material. A bias magnetic field is then applied to the substrate together with its epitaxial film. Polarized light is transmitted onto the substrate with its associated layers and is reflected through the epitaxial layer and back out of the substrate. The existing magnetization, within the epitaxial film, interacts with nearby magnetic fields associated with eddy currents flowing adjacent to flaws in the target material, such that the domain structure of the epitaxial film is altered.