Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to acquire a monitoring output from a first distributed feedback (DFB) fiber laser sensor at least partially bonded to a piezoelectric portion of a downhole device, to demodulate the monitoring output to determine a frequency shift in a lasing frequency of the DFB fiber laser sensor, and to correlate the frequency shift to a measure of magnetic field strength to determine a strength of a downhole magnetic field. Additional apparatus, systems, and methods are disclosed.

Abstract: A device includes a diamond assembly. The diamond assembly includes a diamond with a plurality of nitrogen vacancy centers and electrical components that emit electromagnetic waves. The device also includes a light source configured to emit light toward the diamond and a photo detector configured to detect light from the light source that traveled through the diamond. The device further includes an attenuator between the diamond assembly and the photo detector. The attenuator is configured to attenuate the electromagnetic waves emitted from the electrical components of the diamond assembly.

Abstract: An implant with magnetic field recognition, such as an implant that recognizes fields generated by a magnetic resonance imaging (MRI) device. The implant includes at least one voltage source, at least one control unit, at least one communication coil and an optical structure with a Faraday element. The optical structure includes at least one first and second polarization filters and at least one light detector.

Abstract: A method for performing sub-nanometer three-dimensional magnetic resonance imaging of a sample under ambient conditions using a diamond having at least one shallowly planted nitrogen-vacancy (NV) center. A driving radio-frequency (RF) signal and a microwave signal are applied to provide independent control of the NV spin and the target dark spins. A magnetic-field gradient is applied to the sample with a scanning magnetic tip to provide a narrow spatial volume in which the target dark electronic spins are on resonance with the driving RF field. The sample is controllably scanned by moving the magnetic tip to systematically bring non-resonant target dark spins into resonance with RF signal. The dark spins are measured and mapped by detecting magnetic resonance of said nitrogen-vacancy center at each of said different magnetic tip positions. The dark-spin point-spread-function for imaging the dark spins is directly measured by the NV center.

Abstract: A distributed electromagnetic (EM) wave filter includes: a cavity; upper and lower ground planes on top and bottom surfaces of the cavity, wherein the upper and lower ground planes are in electrical contact; a plurality of electromagnetically coupled resonators in said cavity between the upper and lower ground planes that define respective transmission lines, wherein the plurality of resonators are not connected to each other by a conductive connection; an input port coupled to a first one of the plurality of resonators to receive an EM wave; an output port coupled to a last one of the plurality of resonators to output a filtered EM wave; and a plurality of conductive structures between adjacent resonators, respectively and connected to one or more of the upper and lower ground planes.

Abstract: Absorption based detection of spin states of spin impurities within a solid-state spin system, such as NV centers in diamond, is implemented by measuring the absorption intensity of an optical signal applied to the spin impurities, i.e. change in intensity of the optical signal after the signal has been transmitted through the solid-state spin system. During optical excitation of the spin impurities, microwave pulses are applied to the sample at a frequency tuned to the ESR frequency. The relative populations of the spin states of the impurities, which provides information regarding variables of interest such as an external magnetic field or a quantum information protocol, is determined from the ratio of the absorption intensity of the optical signal when the microwave pulses are turned on, to the absorption intensity of the optical signal when the microwave pulses turned off.

Abstract: Systems and methods for precision optical imaging of electrical currents and temperature in integrated circuits are disclosed herein. In one aspect of the disclosed subject matter, a method for detecting a characteristic of an integrated circuit can include depositing at least one diamond structure, having at least one color center therein, onto a side of the integrated circuit.

Abstract: A system for magnetic detection may include a nitrogen vacancy (NV) diamond material, a radio frequency (RF) excitation source, an optical excitation source, an optical detector, a magnetic field generator, and a controller. The controller may control the excitation sources to apply a first pulse sequence. The controller may receive a first light detection signal due to the first pulse sequence, measure first and second values of the first light detection signal at first and second reference periods, and compute a first measurement. The controller may further control the excitation sources to apply a second pulse sequence, receive a second light detection signal due to the second pulse sequence, measure first and second values of the second light detection signal at first and second reference periods, and compute a second measurement. The first and second measurements may be based on high and low resonance frequencies of the NV diamond material.

Abstract: An atomic cell includes: alkaline metallic atoms, a body portion and window portions forming an inner space in which alkaline metallic atoms are sealed, and a getter material disposed in the inner space. The getter material is an alloy including at least one of titanium, barium, tantalum, zirconium, aluminum, vanadium, indium, and calcium, or an Al—Zr—V—Fe based alloy.

Abstract: A high-resolution sensor of magnetic field sensor system and materials for use in such a system are described. The sensor systems measure a magnetic field using inorganic and/or organic magneto-optically active materials, e.g. polymer material and have an interferometer based on Faraday rotation. The polymer material is preferably in the form of a film. The polymer material has an optical property that is sensitive to the magnetic field, e g the Faraday rotation effect. The present invention also provides a sensor head structure comprising the above polymer material. The sensor head may be designed for use with an optical fiber or with mirrors In particular the present invention provides a fiber Sagnac interferometer to measure the rotation of polarized plane of light. The present invention provides a fiber or mirror based Sagnac interferometer with passive phase bias applied to magnetic field sensing.

Abstract: A crystal film with nitrogen vacancy centers is placed in close proximity to a photon emitter. Excitation illumination is produced to cause the nitrogen vacancy centers to produce photoluminescence. Illumination is produced by the photon emitter, which may be near field or far field and which quenches the photoluminescence intensity using an effect known as Stimulated Emission Depletion (STED). The quenching caused by the photon emitter is detected and analyzed to determine characteristics of the photon emitter. The analysis takes into account the characteristic dependence of the STED on the depletion light power, i.e. the photon source, and a spatial distribution of the light intensity. The analysis may be applied to spatially resolved measurements or an integral value of the photoluminescence quenching. The analysis may determine characteristics such as peak power, power scaling factor, and FWHM of the illumination profile of the photon emitter.

Abstract: There is provided a system (100) for magnetic field detection, comprising a fiber optic interrogator (104) adapted to interrogate a first length of optical fiber (102) with interrogating radiation, detect radiation backscattered from said optical fiber and analyze said detected radiation to provide distributed sensing indicative of mechanical disturbances of said optical, wherein the optic fiber is mechanically coupled to a material whose dimensions vary dependent on applied magnetic field. Changes in dimensions of the optic fiber as can be detected by virtue of changes in back-scattering of light from said fiber using the principles of fiber optic distributed acoustic sensing.

Abstract: A fault location system for a distribution network is disclosed. The fault location system includes at least one sensor and a fault location evaluation apparatus. The at least one sensor is located on the distribution network, for sensing current and dividing the distribution network into at least two regions. The fault location evaluation apparatus includes a fault region determination unit for determining which one of the at least two regions is a fault region where a fault occurs therein by calculating the sensed current from the at least one sensor.

Abstract: A solid state system comprising a host material and a quantum spin defect, wherein the quantum spin defect has a T2 at room temperature of about 300 ?s or more and wherein the host material comprises a layer of single crystal CVD diamond having a total nitrogen concentration of about 20 ppb or less, wherein the surface roughness, Rq of the single crystal diamond within an area defined by a circle of radius of about 5 ?m centered on the point on the surface nearest to where the quantum spin defect is formed is about 10 nm or less, methods for preparing solid state systems and the use of single crystal diamond having a total nitrogen concentration of about 20 ppb or less in spintronic applications are described.

Abstract: A magnetic field measurement apparatus includes a probe beam irradiating unit that radiates a probe beam. A gas cell is arranged on an optical axis of the probe beam and shows a linear dichroism with respect to the probe beam between a first axis and a second axis. Another gas cell is arranged on the optical axis of the probe beam on the opposite side of the probe beam irradiating unit with respect to the gas cell, and shows a linear dichroism with respect to the probe beam between a third axis and a fourth axis, which are different from the first and the second axes. A measuring unit measures a difference between magnetic fields in the gas cells and on the basis of amounts of change of a plane of polarization of the probe beam that has passed through the gas cell and the gas cell.

Abstract: A resistive electromagnet assembly comprises a pair of coils with a gap defined between the coils. The resistive electromagnet assembly is configured to generate a field having a magnetic flux density of at least about 4 Tesla and at a sweep rate to complete a hysteresis loop in less than about 1 minute. A support assembly is configured to support a sample of magnetic material within the gap. An optics module is configured to expose a test region of the magnetic material sample to an optical beam probe while the test region is subjected to the field and to receive a reflected beam from the test region. A processor is coupled to the optics module and configured to measure one or more properties of the magnetic material using the received reflected beam.

Abstract: A magneto-optic surface includes a support; at least two moving elements; each of the moving elements including at least one anchoring point to the support and at least one moving part movable with respect to the support, the moving part including at least one magnetic part; the support and the moving elements being laid out in such a way that under the effect of an external magnetic field, at least one of the moving elements moves with respect to the support such that the optical properties of the magneto-optic surface are modified.

Abstract: A sensor may be configured with a nanocrystal that has a nitrogen-vacancy. The nanocrystal can be positioned proximal a magnetic source, mount, and articulable stage. Various embodiments configure the articulable stage configured to align the nanocrystal and the magnetic source along a common axis to sense magnetic fields about the magnetic source with a sub-nanometer resolution.

Abstract: A method of measuring an electromagnetic field in a formation can include installing an electromagnetic sensor with improved sensitivity, the sensor including multiple optical waveguides and respective multiple materials, and in response to exposure to the electromagnetic field, the materials changing shape in opposite directions. A well system can include an optical electromagnetic sensor which measures an electromagnetic field in a formation, and wherein optical path lengths or phases in optical waveguides of the sensor change both positively and negatively in response to exposure to the electromagnetic field.

Abstract: A system for sensing the position of a movable object includes a polarization maintaining fiber configured to receive light from a light source; an optical system configured to rotate an angle of polarization of the light by a first predetermined angle; a low birefringence fiber connected to the optical system at a first end and having a mirror connected to a second end configured to reflect the light and rotate the angle of polarization at a second predetermined angle, the second end being configured to overlap a magnetic field of the a magnet attached to the object. The angle of polarization is rotated to a third predetermined angle proportional to at least one of the strength of the magnetic field and an amount of the overlap. The optical system is configured to decompose the third predetermined angle into a first component and a second component. A detector is configured to detect a differential between the first and second components indicative of the amount of the overlap.

Abstract: Provided are a method and apparatus for measuring a location of a terminal using a magnetic field. For example, the apparatus may measure a location of a terminal using a magnetic field obtained by a magnetic field sensor and one or more sensor values obtained by a plurality of other sensors.

Abstract: A light divider includes a light guide having a first surface and a second surface that reflect light incident on the light guide, the light guide causing the light to propagate through a portion between the first surface and the second surface, light dividing films that are provided in the light guide and so characterized that the light dividing films not only reflect but also transmit the light, and a plurality of light extracting portions that are provided on the first surface and allow light fluxes that the light dividing films have transmitted to exit through the first surface.

Abstract: A micro-fabricated atomic clock structure is thermally insulated so that the atomic clock structure can operate with very little power in an environment where the external temperature can drop to ?40° C., while at the same time maintaining the temperature required for the proper operation of the VCSEL and the gas within the vapor cell.

Abstract: A beam that passes through a plurality of gas cells a number of times is led to a deflection meter from a light ejecting section, detection of a deflected surface angle is performed and a strength of a magnetic field is measured by a structure in which the plurality of the gas cells is arranged along a light beam between two reflection units or light concentrating units that have a light beam incidence section and a light beam ejecting section and are opposite to each other, and a laser beam that is incident from the light beam incidence section passes through the plurality of the gas cells and then is multiply reflected by both reflection units.

Abstract: A beam that passes through a plurality of gas cells a number of times is led to a deflection meter from a light ejecting section, detection of a deflected surface angle is performed and a strength of a magnetic field is measured by a structure in which the plurality of the gas cells is arranged along a light beam between two reflection units or light concentrating units that have a light beam incidence section and a light beam ejecting section and are opposite to each other, and a laser beam that is incident from the light beam incidence section passes through the plurality of the gas cells and then is multiply reflected by both reflection units.

Abstract: A magnetometer for sensing a magnetic field may include a solid state electronic spin system, and a detector. The solid state electronic spin system may contain one or more electronic spins that are disposed within a solid state lattice, for example NV centers in diamond. The electronic spins may be configured to receive optical excitation radiation and to align with the magnetic field in response thereto. The electronic spins may be further induced to precess about the magnetic field to be sensed, in response to an external control such as an RF field, the frequency of the spin precession being linearly related to the magnetic field by the Zeeman shift of the electronic spin energy levels. The detector may be configured to detect output optical radiation from the electronic spin, so as to determine the Zeeman shift and thus the magnetic field.

Abstract: An optically pumped magnetometer and a magnetic sensing method acquire information as to strengths of magnetic fields in two different directions. A pump light having a circularly polarized component, first probe light having a liner polarized component and second probe light having a linearly polarized component are emitted to a cell containing a group of alkali metal atoms so as to form a crossing region A magnetic field applying unit applies a static magnetic field in a direction of the pump light incident on the crossing region during the emission of the pump light, the first probe light and the second probe light. And, information as to strengths of magnetic fields in two different directions perpendicular to the direction of the static magnetic field in the cell from the rotation angles of a polarization planes of the first and second probe lights during passage through the cell is calculated.

Abstract: An art of measuring a current with a suppressed influence of a switching noise is provided. The art disclosed by the present specification is a current sensor that measures an output current of a switching circuit. The current sensor is equipped with a magneto-optical element that is arranged at a current measurement point, a light source that radiates light onto the magneto-optical element, and a light receiver that receives transmitted light or reflected light of the magneto-optical element. The light source radiates light in synchronization with a carrier signal of the switching circuit. Light is radiated in synchronization with the carrier signal, and a current is measured with the aid of the light. Due to synchronization with the carrier signal, the current can be measured at timings other than a switching timing resulting from a PWM signal that is generated on the basis of the carrier signal.

Abstract: The present invention provides a magnetic biosensor device comprising a sensor cartridge for receiving an assay to be tested, an electromagnetic unit for producing a magnetic field at a sensor surface of the sensor cartridge, and detection means for detecting the presence of magnetic particles close to the sensor surface. The electromagnetic unit is adapted to periodically produce a magnetic field having at least a first and a second magnetic field strength, the ratio of the amount of time of applying the first magnetic field strength to the amount of time of the period of applying the first and the second field strength being varied during the measurement. The invention further provides a method for applying a magnetic field to a sensor surface of a magnetic bio sensor device.

Abstract: A magnetometer for use with a sample including an atomic vapor is disclosed. The magnetometer includes a cell containing the sample such as a multipass cell including a first mirror element and a second mirror element configured so that an incoming light beam injected into the container will reflect multiple times between the first mirror element and the second mirror element. A polarized pump light source is configured to transmit pump light through the cell and pump the sample. A polarized probe light source configured to transmit probe light through the cell and probe the sample. A detector configured to detect a polarization angle or intensity of the probe light transmitted through the sample. A processor may be configured to calculate a precession frequency of the sample based on a first probe light pulse and a frequency correction based on a second probe light pulse.

Abstract: A method for measuring magnetic induction intensity of a magnetic field using a short cavity fiber laser, includes the steps of: a) arranging the short cavity fiber laser, where the short cavity laser has sequentially coupled laser diode pumping source, a wavelength division multiplexer, a fiber Bragg grating, an active optical fiber and a loop mirror; b) fixing the short cavity fiber laser on a magnetostrictive material; c) disposing the short cavity fiber laser and the magnetostrictive material in the magnetic field to be measured, and matching the stretching direction of the magnetostrictive material with the direction of the magnetic field to be measured; d) measuring the drift amount of longitudinal mode output by the short cavity fiber laser; and e) calculating the magnetic induction intensity of the magnetic field to be measured.

Abstract: Systems and methods related to optical current and voltage sensors and, more particularly, to filters for use in such sensors. A fiber optic current sensor comprising: a light source; a polarization beam splitter connected to said light source having a reciprocal port and a non-reciprocal port; a Faraday rotator connected to said polarization beam splitter; a first quarter-wave plate connected to said Faraday rotator; a polarization maintaining fiber connected to said first quarter-wave plate; a second quarter-wave plate connected to said polarization maintaining fiber; a sensing fiber connected to said second quarter-wave plate; a detector connected to said polarization beam splitter via said non-reciprocal port and having an output; and an adaptive filter for filtering said output.

Abstract: An optical pumping magnetometer is provided that is capable of improving the response of the magnetometer with respect to a magnetic field that varies with a period shorter than the transverse relaxation time of electron spin of an alkali metal atom.

Abstract: A system and method for testing capacitance of a load circuit connected to an output pin of a driving circuit In one embodiment, the method may comprise driving a voltage at the output pin to a first voltage; a predetermined current to the output pin; comparing the voltage at the output pin to a reference voltage; and when the voltage at the output pin matches the reference voltage, generating an estimate of capacitance present at the output pin based on a number of clock cycles occurring between an onset of a timed voltage change period and a time at which the voltage at the output pin matches the reference voltage.

Abstract: In order to provide a magnetic field measuring apparatus facilitating the pressure control in a gas cell, or capable of inspecting the internal pressure of the gas cell without using any special process, the magnetic field measuring apparatus is configured such that a process layer of the magnetic field measuring apparatus has such a structure that includes a first hollow portion and a second hollow portion provided opposed to first hollow portion with a first isolation wall interposed therebetween. Alternatively, a method for manufacturing the magnetic field measuring apparatus includes breaking the first isolation wall after generating alkali metal (FIG. 17 and FIG. 20).

Abstract: A system and method for fiber magneto-optic detection are provided, which belongs to the optical application field. The system comprises: a reference device (300) for generating a reference magnetic field signal with known amplitude and shape at a measurement point; a magneto-optic probe (100) for detecting a magnetic field signal of the measuring point, converting the magnetic field signal into an optical signal, and transmitting to a power supply and signal processing module (400) the optical signal sent by the magneto-optic probe; the power supply and signal processing module (400) for transmitting laser light, and converting the optical signal into an electrical signal after receiving it, and demodulating and analyzing the electric signal to acquire the magnetic field information and/or the current information of the measuring point.

Abstract: The cost and size of an atomic magnetometer are reduced by attaching a vapor cell structure that has a vapor cell cavity to a base die that has a laser light source that outputs light to the vapor cell cavity, and attaching a photo detection die that has a photodiode to the vapor cell structure to detect light from the laser light source that passes through the vapor cell cavity.

Abstract: A dual purpose atomic device (DAD) for realizing atomic frequency standard and/or magnetic field measurement based on a hybrid technique comprising of enhanced transmission and polarization rotation by the CPT states is invented. The dual purpose atomic device for realizing atomic frequency standard and/or magnetic field measurement basically involving means for generating bi-chromatic field to facilitate the creation of CPT state in an atomic cell and stabilizing the frequency difference among the said bi-chromatic field to the center of the CPT resonance and thereby realizing atomic frequency standard and/or means for monitoring and analyzing transmitted polarization rotation signal from the CPT enabled atomic gas in a sample cell for measuring magnetic field without scanning the radiofrequency oscillator.

Abstract: A system for fiber DC magneto-optic detection and method thereof are provided. The system comprises a power supply and signal processing module (400), an optical fiber device (200), a magneto-optic probe (100) and a reference device (300). The reference device (300) is mounted in the system, and the measured signal can be corrected via a reference magnetic field pulse signal generated by the reference device (300) so as to eliminate the influence that the environmental factors caused on the measurement, and to obtain accurate measurement data, thus improving measurement accuracy of the system.

Abstract: The present invention relates to a vector magnetometer for measuring the components of an ambient magnetic field. This vector magnetometer comprises an optically pumped scalar magnetometer (2?), a pair of conductive windings (Ex,Ey) having distinct axes (Ox, Oy) and powered by two generators (Gx, Gy) having distinct frequencies. The RF coil (56) of the scalar magnetometer and the conductive windings (Ex,Ex) are mechanically integral with a swivel support (85) mounted on swivel means. The axis of the RF coil is in the same plane as the axes Ox, Oy. The support is swivelled so that this plane is substantially orthogonal to the ambient magnetic field.

Abstract: A magnetic field sensor includes a driving element through which an electric current circumnavigates the driving element. A Lorentz force acts on the driving element resulting in a torque about a first axis in response to a magnetic field along a second axis substantially parallel to a plane of a substrate. The driving element is coiled-shaped. A sensing element of the magnetic field sensor is configured to rotate about the first axis substantially parallel to the plane of the substrate in response to the magnetic field and a coupling element mechanically couples the driving element to the sensing element. The driving element, the sensing element, and the coupling element are disposed in the plane, substantially parallel to the substrate. At least two anchors are configured to connect the driving element, the sensing element, and the coupling element to the substrate.

Abstract: The present invention relates to a portal monitoring system that uses distributed sensing to detect metallic objects passing through the portal. The system comprises a length of fibre optic (102) comprising an optical fibre (106) mechanically coupled to a material (108) whose physical characteristics vary dependent on the applied magnetic field. The fibre optic (102) is arranged in the vicinity of a portal (200) and a fibre optic interrogator (104) is adapted to provide distributed sensing on the optical fibre to provide measurement data from a plurality of contiguous portions of said optical fibre at each of a plurality of times. A data analyser processes the measurement data to detect signals characteristic of a disturbance in the magnetic field along the optical fibre. The system of the present invention is able to monitor multiple people passing though a portal at the same time and provide an indication of the location of metallic objects within the portal.

Abstract: A current sensor device. The current sensor device includes a strain distribution converter; an optical fiber coupled with the strain distribution converter; and a magnetostrictive material associated with the strain distribution converter such that a change in shape of the magnetostrictive material causes a change in length of the optical fiber.

Abstract: A magneto-optic surface includes a support; at least two moving elements; each of the moving elements including at least one anchoring point to the support and at least one moving part movable with respect to the support, the moving part including at least one magnetic part; the support and the moving elements being laid out in such a way that under the effect of an external magnetic field, at least one of the moving elements moves with respect to the support such that the optical properties of the magneto-optic surface are modified.

Abstract: An apparatus is provided for determining a target wavelength ? of a target photon beam. The apparatus includes a photon emitter, a pre-selection polarizer, a prism composed of a Faraday medium, a post-selection polarizer, a detector and an analyzer. The photon emitter projects a monochromatic light beam at the target wavelength ? substantially parallel to a magnetic field having strength B. The target wavelength is offset from established wavelength ?? as ?=??+?? by wavelength difference of ??<<?. The Faraday prism has Verdet value V. After passing through the pre-selection polarizer, the light beam passes through the prism and is incident to an interface surface at incidence angle ?0 to the normal of the surface and exits into a secondary medium as first and second circularly polarized light beams separated by target separation angle ? and having average refraction angle ?. The secondary medium has an index of refraction of n0.

Abstract: MEMS magnetometers with optically transduced resonator displacement are described herein. Improved sensitivity, crosstalk reduction, and extended dynamic range may be achieved with devices including a deflectable resonator suspended from the support, a first grating extending from the support and disposed over the resonator, a pair of drive electrodes to drive an alternating current through the resonator, and a second grating in the resonator overlapping the first grating to form a multi-layer grating having apertures that vary dimensionally in response to deflection occurring as the resonator mechanically resonates in a plane parallel to the first grating in the presence of a magnetic field as a function of the Lorentz force resulting from the alternating current. A plurality of such multi-layer gratings may be disposed across a length of the resonator to provide greater dynamic range and/or accommodate fabrication tolerances.

Abstract: A high-resolution sensor of magnetic field sensor system and materials for use in such a system are described. The sensor systems measure a magnetic field using inorganic and/or organic magneto-optically active materials, e.g. polymer material and have an interferometer based on Faraday rotation. The polymer material is preferably in the form of a film. The polymer material has an optical property that is sensitive to the magnetic field, eg the Faraday rotation effect. The present invention also provides a sensor head structure comprising the above polymer material. The sensor head may be designed for use with an optical fiber or with mirrors In particular the present invention provides a fiber Sagnac interferometer to measure the rotation of polarized plane of light. The present invention provides a fiber or mirror based Sagnac interferometer with passive phase bias applied to magnetic field sensing.

Abstract: A polarization microscope optically detects the effect of the magnetic field from a sub-optical resolution magnetic structure on a magneto-optical transducer. The magneto-optical transducer includes a magnetic layer with a magnetization that is changed by the magnetic field produced by the magnetic structure. The saturation field of the magnetic layer is sufficiently lower than the magnetic field produced by the magnetic structure that the area of magnetization change in the magnetic layer is optically resolvable by the polarization microscope. A probe may be used to provide a current to the sample to produce the magnetic field. By analyzing the optically detected magnetization, one or more characteristics of the sample may be determined. A magnetic recording storage layer may be deposited over the magnetic layer, where a magnetic field produced by the sample is written to the magnetic recording storage layer to effect the magnetization of the magnetic layer.

Abstract: The current in a generator circuit breaker is measured using the Faraday effect of an optical sensing fiber looped around the breaker's conductor. The sensing fiber is arranged in a sensing strip, which can be mounted to the enclosure of the generator circuit breaker or to the conductor. Exemplary embodiments can have a wide measuring range and can easily be fitted to new or existing generator circuit breakers.

Abstract: A Fiber-optic current sensor for sensing electric current carried in an electric conductor (18). Its optical section comprises: a light source (1); a directional coupler (2) with two ports (2A, 2B) of two arms each; a radiation polarizer (3); a polarization modulator (4); a fiber line (17) coupled to a current-sensing fiber loop (11); a mirror (10); and a photodetector (22). The first port of the coupler (2) is coupled to the light source (1) and to the photodetector (22). Its second port is coupled via the radiation polarizer (3) to the polarization modulator (4). The polarization modulator comprises a magneto-sensitive element (5), around which a solenoid (6) is wound. The fiber loop (11) comprises a magneto-sensitive optical fiber with embedded linear birefringence. An electronic section comprises a signal generator (21) which drives the solenoid (6); and a signal processing unit which receives the optical signal from the photodetector (22).