Abstract: A magneto-optic modulator and method are provided. An optical waveguide having a magneto-optic active medium is magnetized by a biasing magnetic field. The magnetization of the magneto-optic active medium is modulated thereby causing a variation in the Faraday effect on optical signals passing through the magneto-optic medium. The result is a polarization modulated optical signal.

Abstract: A magneto-optical device includes a waveguide structure that has at least one cladding region and core region. The cladding region and core region comprise semiconductor alloy materials. Either the at least one cladding region or the core region is doped with ferromagnetic materials so as to increase the magneto-optical activity of the device.

Abstract: A structured material is disclosed with magneto-gyrotropic characteristics including at least one continuous structurally-chiral material. The structured material has an electric permittivity and a magnetic permeability at least one of which varies within the structured material along a first direction in a repetitious fashion wherein a repetition unit includes a chiral component and is at least 25 nm in length. The structured material exhibits non-reciprocal electromagnetic wave propagation velocity characteristics along a second direction that includes a non-zero component along the first direction.

Abstract: The present invention is to provide an arrayed waveguide-embedded optical circuit with reduced loss at a groove and an optical functional element using for the arrayed waveguide-embedded optical circuit. The arrayed waveguide-embedded optical circuit according to the present invention comprises a waveguide, a groove formed across the waveguide and two or more spot-size transformer pairs whose members face each other across the groove.

Abstract: An optic system including an integrated variable optical attenuating device for attenuating an input optical signal, the integrated optical variable attenuating device including a first electrically controllable attenuating element and a second electrically controllable attenuating element cascaded together, the first attenuating element having a first range of optical attenuation smaller than that of the second attenuating element but requiring less input power than the second attenuating element to switch between levels of attenuation within the first range of attenuation, and wherein the optic system further includes electrical circuitry for controlling the first and second attenuating elements in coordination with one another so as to achieve the desired level of total attenuation of the optical signal.

Abstract: A device and method for collecting subject responses, particularly during magnetic imaging experiments and testing using a method such as functional MRI. The device comprises a non-metallic input device which is coupled via fiber optic cables to a computer or other data collection device. One or more optical switches transmit the subject's responses. The input device keeps the subject's fingers comfortably aligned with the switches by partially immobilizing the forearm, wrist, and/or hand of the subject. Also a robust nonmetallic switch, particularly for use with the input device.

Abstract: A method and apparatuses are provided for switching an optical element into and out of an optical path. The apparatus comprises an arm assembly having an axis, first and second arms, first and second latch mechanisms, a stop element, and a solenoid. The first and second arms are coupled to the axis, and one of the arms is configured to selectively rotate relative to the other between first and second rotational positions. The latch mechanisms are mounted to the first arm at first and second mounting positions. The stop element is coupled to the second arm and positioned between and capable of contacting the latch mechanisms. The solenoid is coupled to the arm assembly and configured to provide kinetic energy to the one of the first and second arms configured to rotate to thereby cause the stop element to selectively contact the first latch mechanism and the second latch mechanism.

Abstract: A system and method are disclosed for an optical backplane in an electronic processor that comprises of a plurality of processing units. The backplane is comprising of a network of optical waveguides which can guide polarized light. Furthermore, the backplane has magneto optic routers for steering light at the vertexes of the network, and the backplane also has optical devices for operationally connecting the processing units to the network. The backplane network affords an optical interconnection amongst all of the processing units.

Abstract: The present invention provides an electro-optical device, characterized in that it comprises two plane optical substrates (100) each having at least one optical waveguide (110), and a nematic liquid crystal (200) inserted between them, in which the liquid crystal (200) is split into two separate active zones (210, 220) serving to control coupling/decoupling of a respective one of the TE and TM polarizations of a light signal injected into the waveguides (110).

Abstract: A magneto-optical isolator (20) for an optical circuit. The isolator includes a substrate, and an optical channel (350) disposed next to the substrate. The optical channel and substrate are configured to transmit optical radiation within the optical channel. The isolator further includes a photonic-crystal rotator (24) formed with the substrate and the optical channel. The rotator has at least one defect (52) and magnetic (M) and non-magnetic (N) materials.

Abstract: An optical waveguide for guided an incident light is formed on a substrate having an electro-optic effect. A first buffer layer is formed to cover an upper surface of the substrate. A conductive film is formed above the first buffer layer. A center electrode and a ground electrode are formed for applying a voltage in order to induce an electric field in the optical waveguide. A second buffer layer is formed between the conductive film and at least one of the center electrode and the ground electrode. The conductive film is formed to be present on at least a part below the ground electrode. A light guided through the optical waveguide is modulated by changing a phase by a voltage applied to the optical waveguide. Thereby, a thermal drift can be effectively restricted so that an optical modulation device having excellent electric characteristics can be realized.

Abstract: A moving body (10) is composed of a main body (11), piezoelectric elements (13), (13′) secured to the sides of the main body in the traveling direction thereof, and coils (12), (12′) secured to the piezoelectric elements (13), (13′). A magnet is disposed on a guide rail and the coils (12), (12′) are energized, and whereby the moving body (10) can be moved a long distance at high velocity by a magnetic type linear motor system. Further, the coils (12), (12′) are energized, the main body (11) is pressed against the guide rail on which the magnet is mounted by the magnetic force that is generated by the energization of the coils (12),(12′) and the piezoelectric elements (13), (13′) are extended and contracted by a voltage applied thereto, thereby the moving body (10) is impact driven. With this operation, the moving body can be micro driven at a pinpoint accuracy.

Abstract: The present invention seeks to provide a GFF with a technique amenable to manufacturing in large volume and having a filter with a more precise control of the spectral response.

Abstract: Provided is a 2×2 optical switch includes a substrate, a first input fiber and a first output fiber, a second input fiber and a second output fiber, a rotating mirror, torsion bars, and an electrostatic force generating part. The first input fiber and a first output fiber are arranged at a predetermined distance from a central point in a first optical path passing through the central point over the substrate. The second input fiber and a second output fiber are arranged at a predetermined distance from the central point in a second optical path that passes through the central point and is orthogonal to the first optical path. The rotating mirror is positioned at around the central point and turns on a turning shaft. The torsion bars support the rotating mirror and the electrostatic force generating part supplies a drive force to the rotating mirror.

Abstract: A system and method are disclosed for an optical backplane in an electronic processor that comprises of a plurality of processing units. The backplane is comprising of a network of optical waveguides which can guide polarized light. Furthermore, the backplane has magneto optic routers for steering light at the vertexes of the network, and the backplane also has optical devices for operationally connecting the processing units to the network. The backplane network affords an optical interconnection amongst all of the processing units.

Abstract: An optical variable attenuator is provided including polarizers for extracting a predetermined polarized wave component from an input optical signal, an array of Faraday rotators formed of a ferromagnetic material and arranged in series for rotating the plane of polarization of the input signal, electromagnetic coils for supplying magnetic fields to the Faraday rotators, and current supply control circuits for setting the polarization-rotating angle of the array by controlling the intensity of the magnetic fields supplied to the Faraday rotators. The polarization-rotation angle of the array can be finely adjusted and maintained, even when the magnetic fields are not continuously supplied to the Faraday rotators.

Abstract: Miniature optical devices, including circulator array devices, are fabricated using thin film coating technology. A typical optical device according to the present invention includes a spatial walkoff plate (SWP) coupled on opposite ends to first and second polarization orientation elements. First and second polarization beam splitter (PBS) elements are coupled to the first and second polarization orientation elements, respectively. The PBS elements are formed using thin film coating techniques and each includes an array of port coupling regions for coupling to an array of input/output fiber port assemblies. The SWP may be formed using thin film coating techniques or cut from a birefringent single crystal. Each polarization orientation element includes a Faraday rotator element, and in some embodiments, each also includes a wave plate formed using thin film coating techniques.

Abstract: A wavelength dependent optical device comprising: at least two optical Ports (21, 22); a first series of polarisation modifying optical components (23, 25, 27, 28) placed between the two Ports and a first dielectric mirror (29); the first dielectric mirror (29) operating substantially in reflectance mode at a first predetermined wavelength range and substantially in transmission mode at a second predetermined wavelength range; at least one second polarisation modifying optical component (30) placed between the first dielectric mirror (29) and a second mirror (31); the second mirror (31) operating substantially in reflectance mode at the second predetermined wavelength range; wherein light emitted from the first Port (21) at the first predetermined wavelength range is transmitted to the second Port (22), and light emitted from the first Port (21) at the second predetermined wavelength range is transmitted away from the second Port (22).

Abstract: An optical signal processing apparatus includes a YIG monocrystal serving as a magnetic body. A microstrip is provided on one main face of the YIG monocrystal, and microwaves are input to the microstrip. In order to input a laser beam into the YIG monocrystal, a semiconductor laser, a first lens, and a polarizer are disposed on the outside of one side surface of the YIG monocrystal with respect to the widthwise direction thereof. In order to detect a laser signal output from the YIG monocrystal, a analyzer, a second lens, and a photo detector are disposed on the outside of the other side surface of the YIG monocrystal with respect to the widthwise direction thereof.

Abstract: A ferrule connection optical isolator with an optical fiber, wherein the optical isolator includes a ferrule with at least one processed end surface. The optical fiber consists of two kinds of materials and has a concentric level difference between the materials. A small cylindrical magnet having a size larger than the outer diameter of the level difference portion but smaller than the outermost diameter of the ferrule is connected to the level difference portion. A guide ring is inserted and fixed in the magnet, and an optical element that consists of at least one polarizer and at least one Faraday rotator is connected and fixed in the guide ring.

Abstract: This invention is related to method for assembling an optical attenuator to attenuate an optical beam. The method includes a step of a) collimating the optical beam from an input optical waveguide into a substantially collimated beam comprising an upper segmented-portion and a lower segmented-portion. The method further includes steps of b) transmitting the collimated onto a phase shifting means comprising at least an upper phase shifting means for generating a phase difference between the upper segmented-portion and the lower segmented-portion and c) generating a self-interference between the upper segmented-portion and the lower segmented-portion of the collimated beam and focusing the collimated beam into an output optical waveguide with an attenuation resulting from the self-interference.

Abstract: An electric optical fiber grating has a central wavelength. The central wavelength of an optical fiber grating can be adjusted under strain. The filter includes a bimetal plate, an elastic structure and an solenoid to achieve the goal of switching the central wavelength of an optical fiber grating. Meanwhile, the bimetal plate can also provide proper passive compensation according to the temperature effect around them so that it is not necessary for the optical fiber grating that can switch central wavelengths, to monitor and conduct feedback control at all times. Thus it does not consume power. Therefore, the electric optical fiber grating filter can both achieve the goal of switching central wavelengths and has the advantage of not being sensitive to temperature.

Abstract: An apparatus and method for controlling a coordinate position and/or orientation of a stylus. The apparatus functions by positioning an armature coupled to the stylus, which is disposed within a magnetic fluid. The magnetic fluid is contained within a cavity defined in a non-magnetic body. A controllable active magnetic field-generating structure disposed in proximity to the cavity is used to generate a variable magnetic field that acts upon the magnetic fluid, causing it to be displaced, thereby enabling the armature to be moved to a desired coordinate position and/or orientation. In one implementation, the invention may be used in free space optical communication systems, whereby the stylus comprises the end portion of a fiber optic cable that may be positioned so as to maximize the energy levels of both transmitted and received optical signals.

Abstract: An optical signal transmission system equipped with a magneto-optical modulator is provided. The magneto-optical modulator works to modulate an optical beam emitted from a light source and consists of a polarizer, a magneto-optical element, an analyzer, a dc field generator, a high-frequency field generator, and an impedance adjuster. The dc field generator works to apply a dc bias field to the magneto-optical element. The high-frequency generator is responsive to the high-frequency signal from said high-frequency signal generator to apply a high-frequency field to the magneto-optical element. The impedance adjuster works to adjust impedance of the high-frequency field generator for establishing effective transmission of the high-frequency signal to the high-frequency field generator, thereby increasing a modulation range up to frequencies higher than an upper limit of typical magneto-optical modulators.

Abstract: This invention provides a transparent, paramagnetic polymer composition in which a polymer is complexed with sufficient rare earth ions, particularly ions selected from ions in the group of elements 64-69, to provide a polymer with a magnetic mass susceptibility greater than 20×10−6 emu/g measured at 298° K.

Abstract: A variety of polarization independent optical isolators, including a single stage polarization independent optical isolator, a single stage broadband polarization independent optical isolator, a double stage polarization independent optical isolator, a double stage broadband independent optical isolator, and an optical isolator/monitor/amplifier, provide improved isolation characteristics and functionality. Optical systems are based upon input light traveling twice through the optical isolator/monitor/amplifier, and upon input light traveling twice through the optical isolator/monitor/amplifier connected in cascade with a double stage broadband polarization independent optical isolator.

Abstract: An optical isolator comprises an optical element assembly (10) including a Faraday rotator (1) and a pair of polarizing elements (2) one of which is arranged on a light-input side of the Faraday rotator (1) to serve as a polarizer and other of which is arranged on a light-output side to serve as an analyzer. The optical element assembly (10) is received at the center of an inner bore or a cavity of a cylindrical iron-chromium-cobalt (Fe—Cr—Co) magnet (5). The Faraday rotator (1) comprises a magnetic garnet thick film which is a Bi garnet thick film remarkably low in saturation magnetization as compared with a rare-earth garnet. The Fe—Cr—Co magnet (5) serves as a field-application magnet for generating a magnetic field applied to magnetize the Bi garnet thick film and also as an isolator casing because it is excellent in magnetic and mechanical characteristics.

Abstract: System and method for attenuation of light or optical switching of light, or a portion thereof, from a first optical fiber to a second optical fiber in a relatively short time interval. Two fibers are physically coupled over a length that is equal to an initial optical coupling length, where full transfer of light energy can occur from the second fiber to the first fiber. The physical coupling region of the fibers is immersed in a magnetostrictive material upon which a magnetic induction of controllable strength is impressed. When the magnetic induction is changed from a first selected value to a second selected value, optical switching or optical attenuation occurs between the fibers or in a single fiber. The optical coupling apparatus may include a Mach-Zehnder interferometer and may include first and second magnetostrictive materials in the first and second arms, respectively, of the interferometer.

Abstract: A low-rate data transmission system and method are disclosed that use the Faraday effect to modulate the polarization state of light traveling in an optical fiber. The resulting change in polarization is used to communicate information over the fiber. The low-rate data transmission system includes a low-rate signal source producing current in a wire coil wrapped around an optical fiber. Information is conveyed in accordance with the present invention by the selectively introducing a polarization change into the light carried by the fiber. Generally, the source light at the input of the optical fiber can be randomly polarized and information is conveyed in accordance with the present invention by the presence or absence of a predefined polarization introduced into the light. The longitudinal magnetic field produced by a current in the coil rotates the plane of polarization of the light, in accordance with the well-known Faraday effect.

Abstract: A non-reciprocal optical phase shifter comprises a plurality of switchable phase shifter stages. Each phase shifter stage is optically coupled to an adjacent phase shifter stage. At least one phase shifter stage produces a fixed Faraday rotation on the optical signal components. The plurality of switchable phase shifter stages is optically coupled to at least one phase shifter stage to produce a cumulative non-reciprocal phase shift that is the summation of the phase shifts of the plurality of switchable phase shifter stages and the at least one phase shifter stage.

Abstract: A short intense pulse of radiation is generated by shining radiation through a magneto-optical material and providing multiple stimulations to the material. The material is excited multiple times to rapidly change a property of the radiation, such as the angle of its polarization. The first excitation rotates the polarization in a first direction and the second excitation can rotate the polarization further. Alternatively the second excitation can bring the polarization back to its initial direction. Effect of lengthy relaxation times in the material cancel each other out and the pulse of light has a length that depends on the time difference between the two excitations and the spacing between them. This allows a pulse of light to be produced that has more rotation or has a shorter pulse width than the time for excitation plus the time for normal relaxation of the magneto-optical material.

Abstract: Optical isolators for use in fiber optic networks utilizing a birefringent wedge set with a Faraday rotator disposed between the birefringent wedges. In a first embodiment a polarization maintaining optical isolator is disclosed which will maintain the polarization of the light which passes through it in a forward direction and block light in the reverse direction. In a second embodiment a single polarization optical isolator is disclosed which will pass only a single linear polarization of the light in a forward direction and block any light in the reverse direction.

Abstract: The invention concerns to area of magneto-optics, nonlinear-optics, fiber optics. The invention allow to amplify Faraday effect drastically and obtain a high level of modulation of optical radiation at very small amplitudes of modulating variable current. So it provides a very high speed of modulation of optical radiation. It also gets an opportunity of reading the information with higher density of record. The modulator on the basis of magneto-optical Faraday effect contains optically connected: optical element made from magneto-optical material with means creating a variable magnetic field in it, a nonlinear-optical waveguide and a separator of waves having orthogonal polarizations. The possibility for rejection of atmosphere fluctuation and jamming is provided. The nonlinear-optical waveguide can be made on the basis MQW-type structure.

Abstract: A method for fabricating a transformer of linearly polarized light to elliptically polarized light is presented. The method involves twisting a birefringent fiber through angles that depend on the polarization desired. This technique obviates the need to splice fibers, as in common approaches. In the final step of the method, the polarization can be fine tuned by heating the fiber to cause the core of the fiber to diffuse into the cladding. Using this transformer of polarized light, a current sensor is presented that exploits the Faraday Effect in a Sagnac interferometer.

Abstract: A variable optical attenuator comprises a Faraday rotator including a ferromagnetic garnet film disposed input/output single mode optical signal paths. A collimating/lensing arrangement is used to focus the optical signal between the input/output signal paths and the ferromagnetic garnet film. The ferromagnetic material exhibits multiple types of magnetic domain such that an optical signal will experience ±rotation as its passes through the film. A 90° garnet film thus provides ±90° rotation, resulting in a fill 180° directional difference between the optical signal components. The amplitudes of these signals will thus cancel, providing an essential “full” attenuation of the optical signal. The application and adjustment of a magnetic field to the garnet film controls the strength (i.e.

Abstract: A magnetostatic wave device comprises a magnetic garnet single crystal film. The single crystal film magnetic garnet is represented by the general formula of Y3Fe5-x-yInxMyO12 (wherein M is at least one of Ga, Al and Sc, 0.01≦x≦0.45 and 0≦y≦1.2) and the Curie temperature is about 150° C. to 285° C.

Abstract: According to the present invention, a hybrid magnetic substrate is provided, which includes: a magnetic substrate; and a holding substrate directly bonded to the magnetic substrate through at least one of a hydrogen bond and a covalent bond. Furthermore, a method for producing a hybrid magnetic substrate having the magnetic substrate and the holding substrate is provided, which includes the steps of: cleaning a surface of the magnetic substrate to be bonded and a surface of the holding substrate to be bonded; allowing the cleaned surfaces to be subjected to a hydrophilic treatment; and attaching the surfaces, which are subjected to the hydrophilic treatment, to each other to directly bond the magnetic substrate to the holding substrate.

Abstract: A reversible optical isolator and optical amplifier based on the optical isolator. The reversible isolator is constructed from a Faraday rotator having a magnetic field direction that is determined by a control signal applied thereto. The Faraday rotator is sandwiched between first and second polarization filters. The polarization filters may be constructed from polarization splitters in series with half-wave plates. The allowed direction of propagation of an optical signal through the reversible optical amplifier is determined by the magnetic field direction in the Faraday rotator. An optical amplifier according to the present invention includes an optical gain element in series with one or two reversible optical isolators.

Abstract: A fiber optic magnetic switch device comprising a fiber optic transceiver ving a light source and a length of fiber optic cable for transmitting light to a fiber optic magnetic switch. The switch includes a magnet, a position biased shutter operably attached to the magnet, a pair of SMA type connectors positioned to align the shutter there between, a repelling orientation magnet positioned proximate the shutter to orient the shutter in a first, secured repelling orientation to allow light through the shutter and further operable to prevent passage of light through the shutter in a second, unsecured condition. An alarm signals the failure of light to be transmitted along the fiber optic cable and through the shutter. Alternatively, the device may include a second fiber optic cable operable between the transceiver and the alarm during operation of the device and positioned to activate the alarm upon interruption of light transmission therein such as when it is tampered with.

Abstract: A method of magneto-optically modulating light comprises the steps of linearly polarizing the light on its transmission path, and placing a magneto-optic effect element on the transmission path of the polarized light with the spontaneous magnetization direction of the magneto-optic effect element being substantially parallel with the transmission path. The plane of polarization of the polarized light is rotated about the transmission path in the absence of the magnetic field applied to the magneto-optic effect element having the polarized light pass therethrough. The method further comprises the step of applying the magnetic field to the magneto-optic effect element with its internal magnetization being oriented in a direction perpendicular to the transmission path. The plane of polarization of the polarized light is maintained in its initial state in the presence of the magnetic field applied to the magneto-optic effect element having the polarized light pass therethrough.

Abstract: The instant invention relates to a method and an arrangement for the space-based operation of quantum-optical amplifiers embodied as optical waveguides, while taking the special conditions to be found in space into consideration. An amplifier housing 2 filled with nitrogen has a cutout into which a plan-parallel quartz glass plate 4 has been fitted, through which light beams can enter and leave the housing. The amplifier housing 2 rests on heat-insulating supports 3a, 3b and is temperature-stabilized by a Peltier element 5. The amplifier housing 2 is filled with nitrogen in order to achieve operating conditions similar to those on earth.

Abstract: There is provided a magnetostatic wave device which operates even with a substitution R, A:YIG having a small film thickness and which has a wider operational frequency band. A magnetostatic wave device comprising a magnetic garnet film is provided which is made of a material expressed by a general formula: (Y.sub.1-r R.sub.r).sub.3 (Fe.sub.1-a A.sub.a).sub.5 O.sub.12 where R is at least one selected from among La, Bi, Gd and Lu; A is at least one selected from among Al, Ga, In and Sc; r and a are within the ranges 0.ltoreq.r.ltoreq.1 and 0.ltoreq.a<1, respectively; and r and a can not be zero at the same time. Further, the crystal structure of said magnetic garnet film is a superlattice.

Abstract: An optical interferometer incorporating a signal strength modulated optical phase delay, such as a Kerr effect element in one of its arms is employed to improve the cross-talk isolation/extinction ratio of an optical switch, amplitude modulator, or amplitude modulated optical transmitter. The Kerr element is constructed so that its intensity dependent optical path length is such as to provide destructive interference at the interferometer output when the light input to the interferometer is low, and constructive interference when the input is high. The place of the Kerr effect element can alternatively be taken by an electro-optic modulator driven with an electrical version of the data modulation appearing on the optical signal.

Abstract: An optical system and method for selective transmission of light between a source of light and a set of storage disks along an optical path that includes at least one individual optical fiber. In an optical system and method that uses a magneto-optical storage medium, single-mode polarization maintaining optical fibers and a compensator may be included. Alternatively, the optical system and method may include an optical switch.

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 high-quality magneto-optic signal is obtained by setting an optimum phase condition at the time of reproducing the land or groove record in a magneto-optic recording medium. By adjusting the angle of inclination of a wavelength plate, an optimum amount of phase compensation is provided to the land or the groove. Furthermore, the inclination of the wavelength plate is made variable, and the DC component of the magneto-optic signal is used as an adjusting signal in order to effect a phase compensation. In reproducing the signals recorded in the land and/or groove, an optimum amount of phase compensation is provided in each case, whereby a best producing condition is obtained, and high-density records can be realized.

Abstract: In accordance with the invention, a tunable fiber grating comprises a fiber grating secured to a magnetostrictive body so that magnetostrictive strain will be transmitted to the grating. An electromagnet is disposed adjacent the magnetostrictive body for applying a magnetic field along the body. Control of the current applied to the electromagnet permits control of the strain transmitted to the fiber grating, and thus control of the grating spacing and reflection frequency. In a preferred embodiment the magnetostrictive body is cylinder bonded along the grating. In alternative arrangements, the magnetostrictive effect can be mechanically amplified. An add/drop multiplexer employing the tunable gratings is described.

Abstract: In accordance with the invention, a tunable fiber grating comprises a fiber grating secured between a pair of magnets so that magnetic force (repulsive or attractive) applied to the magnets is transmitted to the grating. An electromagnet is disposed adjacent the magnets for applying the field to magnetize them. Control of the current applied to the electromagnet permits control of the force transmitted to the fiber grating and, thus, control of the grating strain, spacing and reflection frequency. In a preferred embodiment the electromagnet is actuated to produce magnetic pulses which control the remanent force between the two magnets, eliminating the need for continuous power. An add/drop multiplexer employing the tunable gratings is described.

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.