Abstract: A magneto-optical device is provided with a non-magnetic substrate, a magneto-optical crystal embedded in recessed portions formed in the surface of the non-magnetic substrate at positions where pixels are to be located, and a partitioning wall monolithic with the non-magnetic substrate and magnetically separating the magneto-optical crystal from each other at the position of a gap between the pixels, wherein the entire surface of the magneto-optical device is flattened.

Abstract: Magneto-optical crystals of each pixel of a magneto-optical device are magnetically and completely separated, and the entire surface thereof is flattened. Disclosed is a magneto-optical device including a non-magnetic substrate, a magneto-optical crystal embedded in recessed portions formed in the surface of the non-magnetic substrate at positions where pixels are to be located, and a partitioning wall monolithic with the non-magnetic substrate and magnetically separating the magneto-optical crystal from each other at the position of a gap between the pixels, wherein the entire surface of the magneto-optical device is flattened.

Abstract: An optical attenuator with increased dynamic range and reduced temperature-dependence over the dynamic range. The optical attenuator has a Faraday rotational angle variable device which applies an external magnetic field to light polarized by a garnet crystal, and a polarizer and an analyzer disposed at the front and rear of the optical axis of the device. There is an angle x formed between the plane of polarization of the light incident to the garnet crystal and the magnetic field orthogonal to the optical axis, where an angle y is formed between the polarizer and the analyzer, and the angle x is set to satisfy {(?z/2)+90×n}?12<x<{(?z/2)+90×n}+12 (n=0, 1, 2 or 3), where z=y±90; z is the angle of rotation of the plane of polarization caused by the Faraday rotational angle variable device.

Abstract: It is possible to reduce the size of a magneto-optical device, increase the speed of optical control, simplify power supply structure and its control, and maintain a Faraday rotation angle in an arbitrary state even after shut-off of the excitation current. The magneto-optical device includes a magnetic yoke (10) made of a high-permeability magnetic material, the magnetic yoke including a tabular portion (16) and four pillar portions (18) protruding from one side of the tabular portion (16), a coil (12) wound on each of the pillar portions, and a magneto-optical element (14) arranged in an open-magnetic-circuit region surrounded by the end portions of the four pillar portions. A magnetic field obtained by a coil is applied to the magneto-optical element.

Abstract: It is possible to reduce the size of a magneto-optical device, increase the speed of optical control, simplify power supply structure and its control, and maintain a Faraday rotation angle in an arbitrary state even after shut-off of the excitation current. The magneto-optical device includes a magnetic yoke (10) made of a high-permeability magnetic material, the magnetic yoke including a tabular portion (16) and four pillar portions (18) protruding from one side of the tabular portion (16), a coil (12) wound on each of the pillar portions, and a magneto-optical element (14) arranged in an open-magnetic-circuit region surrounded by the end portions of the four pillar portions. A magnetic field obtained by a coil is applied to the magneto-optical element.

Abstract: A polarized-light separating/combining element is obtained which can suppress deviation in a direction of rays (angular error), reduce beam coupling loss and improve extinction ratio. Size reduction and loss lowering is achieved for an optical device (optical circulator or optical switch), to enable manufacture at a low cost and with ease. A polarized-light separating/combining element has a transparent member having flat surfaces parallel with each other on which both parallel surfaces, polarized-light separating/combining films are formed respectively, wherein both polarized-light separating/combining films are faced to air. By using the polarized-light separating/combining element, various kinds of optical devices (optical circulators or optical switches) can be formed. Particularly, it is effective for realizing a low crosstalk characteristic in a matrix optical switch.

Abstract: A polarized-light separating/combining element is obtained which can suppress deviation in a direction of rays (angular error), reduce beam coupling loss and improve extinction ratio. Size reduction and loss lowering is achieved for an optical device (optical circulator or optical switch), to enable manufacture at low cost and with easiness. In the present invention, a polarized-light separating/combining element 10 has a transparent member 12 having flat surfaces parallel with each other on which parallel both surfaces, polarized-light separating/combining films 14 are formed respectively, wherein the both polarized-light separating/combining films are faced to air. By using the polarized-light separating/combining element, various kinds of optical devices (optical circulators or optical switches) are structured. Particularly, it is effective for realizing a low crosstalk characteristic in a matrix optical switch.

Abstract: Provided are an optical rotator which is capable of switch-operating at high speed, small in size and low in price, an optical switch readily compatible with an array structure and matrix form, and a variable optical attenuator readily compatible with an array structure. In the present invention, an optical rotator 14 comprises a lamination coil 10a, . . . , 10c having a through-hole and a Faraday element 11 arranged in the through-hole or a vicinity thereof, whereby a magnetic field caused by the coil is applied to the Faraday element. The Faraday element is arranged such that light passes vertically to the main surface thereof in which direction a magnetic field can be applied. A magnetism-holding member of a high magnetic permeable material is preferably arranged at least in a part of an outer periphery of the coil. In case the Faraday element uses a magnetic garnet crystal having a residual magnetization, obtained is an optical rotator having a self-sustaining function.

Abstract: There is provided a Faraday rotation angle varying device in which external magnetic fields are applied from at least two directions to a garnet single crystal having a Faraday effect and a synthesized magnetic field is varied so that Faraday rotation angle of light which transmits through the garnet single crystal is controlled. The device has a base film of garnet single crystal having a rotation angle varied in accordance with variation of a synthesized magnetic field, and a compensating film of a garnet single crystal having a constant Faraday rotation angle. The base film has a wavelength coefficient sign and the compensating film has a wavelength coefficient sign which is different from that of the base film, so that a wavelength variation component of the Faraday rotation angle of the base film is reduced by the compensating film. For example, a fixed magnetic field parallel to a light direction is applied by permanent magnets and a variable magnetic field is applied by an electromagnet.

Abstract: Disclosed is a Faraday rotator capable of reducing the temperature dependence on a Faraday rotation angle, thereby enhancing the temperature characteristic, particularly, in a service environment in which the magnetization direction is variable, and an optical device using the Faraday rotator. The Faraday rotator includes a Faraday element which rotates the polarization plane of polarized light rays passing through the Faraday element when an external magnetic field is applied to the Faraday element.

Abstract: A Faraday rotation angle varying apparatus for controlling a Faraday rotation angle of a light beam passing through a garnet single crystal having a Faraday effect by applying external magnetic fields to the garnet single crystal in two or more of directions and varying a synthetic magnetic field synthesized from the external magnetic fields is disclosed. According to an aspect of the present invention, the garnet single crystal has the (111) plane polished and the light beam is allowed to pass through the garnet single crystal along the <111> direction of the garnet single crystal perpendicular to the (111) plane. A displacement path of a synthetic vector of the external magnetic fields is within a fan-shaped range (peripheral lines of the fan-shape inclusive) of a stereographic projection chart of the garnet single crystal with the (111) plane taken as the center of the chart.

Abstract: Disclosed is a magneto-optical element material composed of a magnetic garnet single crystal which is small in temperature dependency of a Faraday rotation angle, capable of being formed into a film by the LPE, and significantly small in wavelength dependency of a Faraday rotation angle in a specific composition region defined by. The magneto-optical element material is composed of a magnetic garnet single crystal expressed by a composition formula of R.sub.3-x Bi.sub.x Fe.sub.5-v-w-y Ma.sub.v Mb.sub.w Co.sub.y O.sub.12 where R indicates a rare earth element including yttrium, Ma is a trivalent cationic element, and Mb is a tetravalent cationic element; and x, y, v and w satisfy relationships of 0.6.ltoreq.x.ltoreq.1.9, 0.01.ltoreq.y.ltoreq.0.47, 260y-88x+45.ltoreq.0, 500y-30x+37.ltoreq.0, 0.ltoreq.v.ltoreq.1.0, and 0.ltoreq.w.ltoreq.0.35. The material satisfying the following relationships of 0.01.ltoreq.y.ltoreq.0.28 and 800y-130x+45.ltoreq.

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 material made of magnetic garnet single crystals has excellent characteristics particularly in a wavelength band of from 950 to 1070 nm, which is usable for a wavelength 980 nm for pumping light of erbium doped fiber amplifier, and for a wavelength of 1017 nm for pumping light of an praseodymium doped fiber amplifier. One example of the material is made of magnetic garnet single crystals expressed by a composition formula of Nd.sub.3-x Bi.sub.x Fe.sub.5 O.sub.12 (0.5.ltoreq.x.ltoreq.1.9), the single crystals being formed by liquid-phase epitaxial growth on a non-magnetic garnet substrate having a lattice constant <a> specified in the range of 12.61 .ANG..ltoreq.a.ltoreq.12.63 .ANG.. The material is suitably used for a magneto-optical element having a wavelength band from 950 to 1070 nm. The non-magnetic garnet substrate can be made of a material having a composition formula expressed by Gd.sub.3-y Nd.sub.y Sc.sub.2 Ga.sub.3 O.sub.12 (1.0.ltoreq.y.ltoreq.1.4).

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.