96 results about "Verdet constant" patented technology

The invention belongs to the technical field of all-fiber current transformers, and particularly relates to a high-precision high-reliability and all-fiber current transformer. A redundancy design method adopting active optical devices is applied so that output optical power of light source units is enabled to be more stable and stability of light source average wavelength is enhanced. A depolarization head is additionally arranged in an optical path system so that stability and measurement precision of the optical path system can be enhanced. Two beams of light are converted into electric signals to be transmitted to a signal processing unit by utilizing correlation of output light of the two output ends of a second single-mode coupler through a digital signal processing unit, and suppression of light source intensity noise is realized by utilizing a digital circuit subtraction method so that signal-to-noise ratio is enhanced and measurement precision of the system is enhanced. A low birefringence optical fiber Verdet constant and a transformation ratio error generated by change of wave plate phase delay along with temperature are enabled to be mutually compensated via an all-fiber current transformer transformation ratio temperature error automatic compensation technology so that full-temperature measurement precision of the system is enhanced.

The present invention provides an optical in-fiber chiral fiber isolator, capable of transmitting a signal of a predetermined optical polarization in a forward direction therethrough, while rejecting all signals traveling in a backward direction therethrough, and a method of fabrication thereof. In one exemplary embodiment, the inventive optical chiral fiber isolator includes a chiral magneto-optical fiber having a helical pitch profile, a birefringence profile, and an effective Verdet constant profile, at least a portion of which is exposed to a magnetic field of a predetermined magnetic field profile (generated by a proximal magnetic field source), where the magnetic field profile, the chiral pitch profile, the birefringence profile, and the effective Verdet constant profile are selected and configured such that the inventive isolator is capable of transmitting a signal of a predetermined optical polarization in a direction from its input end toward its output end, and to reject all signals in a direction from its output end to its input end.

The invention discloses an interferometry-based optical fiber Verdet constant measuring system. The system comprises an ASE (amplified spontaneous emission) light source, a single-mode optical fiber coupler, a Y-waveguide integrated optical modulator, 1/4 wave plates, Faraday rotator mirrors, a solenoid, a sine alternating-current driving circuit, matching fluid, a probe, an information processing module, a computer and measured optical fibers. The ASE light source, the single-mode optical fiber coupler, the Y-waveguide integrated optical modulator, the measured optical fibers and the Faraday rotator mirrors are connected through optical fibers in sequence. Each 1/4 wave plate is arranged between the Y-waveguide integrated optical modulator and the corresponding measured optical fiber. A signal processing portion comprises a feedback servo circuit, an FPGA (field programmable gate array) module and a phase modulation driving circuit. The system is of an all-optical-fiber structure and simple and convenient to set up; by the aid of the Faraday rotator mirrors, influences of linear birefringence of the optical fibers on measurement can be eliminated, and measurement accuracy is improved; and Verdet constants of various optical fibers can be measured by the system.

The invention discloses faraday magnetic rotation transparent ceramic and a preparation method thereof. The structural formula of the transparent ceramic is shown as Tb3-xAxAl5-yByO12, wherein A is Tm, Lu, Y or Gd; B is Sc or Ga; x is more than or equal to 0 and less than or equal to 2.9; and y is more than or equal to 0 and less than or equal to 5. The preparation method comprises the following steps of: preparing raw materials according to the components of the transparent ceramic with the structural formula of Tb3-xAxAl5-yByO12; adding 0.3 to 0.7 weight percent of ethyl orthosilicate serving as an additive; performing ball-milling, drying and tableting on powder; pressing with cool isostatic pressure of over 200 Mpa to obtain a blank body; pre-sintering to remove organic components; and putting the blank body into a vacuum or hot-press sintering furnace for sintering to obtain the magnetic rotation transparent ceramic with the structural formula of Tb3-xAxAl5-yByO12. The ceramic has high optical transmittance and high Verdet constant in a visible-near infrared band. The preparation method has the advantages of simple preparation technology, low cost, nontoxic preparation process and the like.

A method for improving stability of an optical current sensor is used for solving stability problems in measuring high-voltage current. The technical proposal is that: a current sensing unit and a photoelectric signal processing unit composes a basic system of the sensor. The current sensing unit adopts two current sensing heads which are symmetrically arranged at both sides of the through-flow conductors; an input end of an input collimator of each current sensing head is connected with a light source. An output end of an output collimator is connected with a photoelectric signal processing unit through optical fiber and optical cable; two magneto-optic elements are manufactured with two different materials to remain a monotone functional relationship between a ratio of the verdet constant and temperature. In the invention, the method can compensate influence of the retrieval temperature on the verdet constant while an external reference source need not to be introduced, also greatly improve long-run stability while high accuracy of the sensor is guaranteed simultaneously.

The invention discloses a heavily Tb<3+> doped phosphate glass core composite optical fiber and a preparation method thereof. The cladding material of the optical fiber is K9 glass with excellent optical properties, the fiber core material is heavily Tb<3+> doped phosphate glass, the prepared fiber core glass has high transmission rate and large Verdet constant in visible-near infrared region, also has strong green light emission (542nm) and long fluorescence lifetime. The preparation steps of the optical fiber include: 1. melting of heavily Tb<3+> doped phosphate fiber core glass; 2. processing of an optical fiber perform rod; and 3. controlling of composite optical fiber. The invention employs the fiber core melting method to effectively solve the problem of crystallization caused by drawing of optical fiber with heavily Tb<3+> doped glass. The optical fiber provided by the invention can be used for magneto-optical isolators, magneto-optical modulators, magneto-optical switches and other magneto-optical devices in the optical fiber communication field, optical fiber current transducers, optical fiber magnetic field sensors and other sensing fields, as well as green (542nm) optical fiber lasers.

The invention discloses a test device and method of the Verdet constant of a doped optical fiber. The test device includes an ASE light source, a collimator, a polarizer, a chopper, a lens, an optical fiber tri-axial displacement stage, a solenoid, a direct-current power source, an analyzer, a photoelectric detector, a lock-in amplifier and a computer; and an doped optical fiber to be measured needs no welding and is directly arranged into the center channel of the solenoid so as to be tested. According to the test device of the invention, the chopper and the lock-in amplifier are adopted, so that noises in an optical path can be effectively inhibited, and the accurate measurement of the Verdet constant can be realized; and in a testing process, the angle of the analyzer does not need to be adjusted for many times, and it only needs to switch on and switch off a power source and record the readings of the lock-in amplifier. Compared with a conventional optical fiber Verdet constant test device, the test device of the Verdet constant of the doped optical fiber provided by the invention has the advantages of no welding loss, excellent anti-noise performance, high sensitivity and simple operation, and is suitable for the measurement of the Verdet constants of various kinds of doped silica optical fibers or glass optical fibers.

The invention discloses a sensing head of an all-fiber current transformer. Grooves are respectively formed in an upper cover of the sensing head and a lower cover of the sensing head; a sensing optical fiber, an all-fiber one-fourth wave plate and an optical fiber end surface reflecting mirror form an optical fiber sensing part of the all-fiber current transformer by a welding mode; the optical fiber sensing part is uniformly wound on a sensing framework in a spiral manner; the sensing framework wound with the optical fiber sensing part is placed in the groove of the lower cover of the sensing head and integrally packages the upper cover of the sensing head with the lower cover of the sensing head; a lead head which is internally provided with a lead hole is processed in the upper cover of the sensing head; and a polarization-preserving optical fiber is used as a lead-out end of the sensing head of the all-fiber current transformer, is partially connected with the optical fiber sensing part and is led out of the lead hole. According to the sensing head disclosed by the invention, various negative influences such as linear birefringence, Verdet constant temperature effect and one-fourth wave plate phase delay temperature effect of the optical fiber sensing part can be effectively eliminated.

The invention discloses an optical current transformer based on a dual-wavelength structure. The optical current transformer comprises a first light source 1, a second light source 2, an optical fiber coupler 3, a sensor 4, a first wavelength division demultiplexer 5, a second wavelength division demultiplexer 6, a first photoelectric detector 7 and a second photoelectric detector 8, which are connected in sequence through optical fibers. The sensor 4 is internally provided with the following optical elements in sequence: a first collimator 9, a polarizer 10, a magneto-optical crystal 11, a polarization splitter prism 12, a second collimator 13 and a third collimator 14. The measurement method comprises the following steps: obtaining function relationship between the temperature and Verdet constants of the magneto-optical crystal under two different wavelengths; in the actual measuring process, obtaining rotation angles theta1 and theta2 of two polarized light beams of different wavelengths obtained after passing through the magneto-optical crystal under the effect of an external magnetic field; and carrying out calculation to obtain the temperature T and the magnetic field intensity H, and finally obtaining the measured current value according to the relation between the current I and the generated magnetic field H. Therefore, accuracy of measurement result is improved.

The invention provides a high verdet constant magnetic optic glass and a preparation method thereof. The glass comprises the following raw materials in percentage by mole: 15 to 40 percent of Tb2O3, 0 to 25 percent of Dy2O3, 30 to 60 percent of B2O3 and SiO2, 0 to 30 percent of Ga2O3, 0 to 10 percent of ZnO, 0 to 8 percent of ZrO, 0 to 5 percent of CaF2, 0 to 5 percent of P2O5 and 0 to 10 percent of TiO2. The preparation method comprises the following steps of: weighing and mixing the raw materials in percentage by mole; adjusting the temperature of a heating furnace to 1,250 DEG C, putting the raw materials into a crucible in the heating furnace in turn; heating the mixture to between 1,350 and 1,380 DEG C, and stirring the mixture for 3 to 5 hours; and cooling the furnace to 1,250 DEG C, pouring the materials in the heating furnace and annealing the materials. The verdet constant of the magnetic optic glass reaches -0.425min/Oe.cm (632.8nm), and is far higher than that of international general terbium glass.

The invention discloses a measuring device and a method of a polarization maintaining optical fibre Verdet constant. The measuring device mainly comprises a light source and isolation module, a polarization control injection module, a magnetic field and modulation module, a precision moving platform, a polarization beam splitter, a photoelectric detector, a signal processing module and a peak value detection module. A certain characteristic shaft of an optical fiber to be measured is coupled with a counter shaft of the polarization beam splitter at the exiting end. The measuring method comprises the following steps of changing light sent by a laser into circularly polarized light through the polarization control injection module and then outputting to the optical fiber to be measured, separating the light into two bundles of light through the polarization beam splitter, moving a guide rail to control the position of a magnetic filed, collecting two bundles of light intensity, conducting processing on the two bundles of the light intensity to obtain a corresponding voltage signal peak value, and further calculating a Verdet constant of the polarization maintaining optical fibre. The measuring device is simple and easy to operate, ensures maximum measured sensitivity, simultaneously avoids a measuring error caused by counter shaft operation and angle adjusting of the optical fiber injection end, and further improves measuring precision.

The invention discloses a method and a device for measuring environment temperature change and magnetic induction strength, belongs to the field of photoelectric technology, relates to optical fiber sensing technology, in particular to a method and a device for measuring magnetic induction strength ( or optical fiber Verdet constant) and temperature change based on magneto-optical fiber Bragg optical grating (MFBG). The invention adopts magneto-optical fiber Bragg optical grating, respectively utilizes levorotation and dextrorotation circularly polarized light to emit into MFBG according to intrinsic sensing mode and reflectivity and transmission property, and realizes measuring magnetic induction strength ( or optical fiber Verdet constant) and temperature change simultaneously by detecting luminous power reflection (or transmission) circularly polarized light of MFBG, thus realizing multiple parameter incoherent detection, and having the advantages of convenience, easiness and omission of temperature compensation.

The invention discloses a polarization-maintaining fiber Verdet constant measuring device and a measuring method based on Mach-Zehnder and Michelson interferometers, and belongs to the technical field of fiber application. The measuring device comprises a wave train analysis module which is composed of a Mach-Zehnder interferometer and a Michelson interferometer. The measuring method comprises the following steps: selecting the length of a delay ring; gradually shortening the delay ring by equal length; recording interference fringes when the light of a reference light path interferes with the light of a signal light path; applying a magnetic field, making the light of the reference light path interfere with the light of the signal light path again, and recording interference fringes; and calculating the Verdet constant. The measuring device and the measuring method can be applied to most types of polarization-maintaining fibers and can also be extended to single-mode fibers, and is generally applicable. Measurement can be completed only by intercepting a section of fiber. The measuring sensitivity is high. Engineering application is facilitated.

A Farady rotating phosphorate glass with low non-linear refractivity and high content of Tb3+ for Farady rotator is on the basis of Tb2O3 and P2O5, and contains Tb2O3 (17-26 mol%), P2O5 (70-80), and small quantity of Sb2O3 and/or As2O3, and further including small-quantity of Al2O3, B2O3, SiO2, R2O and RO. Its advantages are high Verdet constant, low non-linear refractivity, high transparency in visual light or near infrared region, and high stability.

The invention provides a Si/Ti doped terbium aluminum garnet Faraday magneto-optical rotation transparent ceramic. The structural formula of the Si/Ti doped terbium aluminum garnet Faraday magneto-optical rotation transparent ceramic is Tb3Al5-xSiyTizO12, wherein y plus z is equal to x, and the numerical areas of x, y and z are as follows: x is greater than or equal to 0.01 and less than or equal to 0.06, y is greater than or equal to 0 and less than or equal to 0.06, and z is greater than or equal to 0 and less than or equal to 0.06. The preparation method of the Si/Ti doped terbium aluminum garnet Faraday magneto-optical rotation transparent ceramic comprises the following steps: proportioning raw materials according to the structural formula Tb3Al5-xSiyTizO12, adding 0.3wt%-0.7wt% of tetraethyl orthosilicate and performing ball milling, drying, sieving and tableting; and then applying isostatic cool pressure of above 150MPa for pressing into a green body; pre-sintering to remove organic components, and then putting the pre-sintered green body into a sintering furnace for sintering to obtain the Tb3Al5-xSiyTizO12 transparent ceramic. The Si/Ti doped terbium aluminum garnet Faraday magneto-optical rotation transparent ceramic has relatively high optical transmittance within the visible-near infrared waveband and is capable of maintaining the relatively high Verdet constant of the original matrix TAG; the transparent ceramic has the advantages of simple preparation process, low cost, short preparation period and the like.

The present invention relates to a terbium vanadate-doped magneto-optical crystal, a growth method and applications thereof. According to the present invention, the molecular formula of the terbium vanadate-doped magneto-optical crystal is CaxMyTb1-x-yVO4, wherein M is a rare earth element and an alkali metal element, x is more than or equal to 0.01 and is less than or equal to 0.5, and y is more than or equal to 0 and is less than or equal to 0.5; the faraday rotation angle of the series of the crystals at 1064 nm is 1.3-1.5 times the faraday rotation angle of the TGG crystal, the crystal has the congruent melting property and can grow through a Czochralski method, the large size crystal easily grows, the raw material cost is low, and the magneto-optical crystal cost can be effectively reduced; the magneto-optical crystal device prepared from the magneto-optical crystal has the large Verdet constant during magneto-optical isolator production, such that the requirement on the magneto-optical crystal length can be reduced; and compared with the magneto-optical crystal in the prior art, the magneto-optical crystal of the present invention has advantages of compact device design, reduction of the number of the magneto-optical crystals used in the isolator, cost reducing and the like. The terbium vanadate-doped magneto-optical crystal of the present invention can further be used for optical switch production.

The invention discloses an apatite type silicate terbium magneto-optical crystal which is high in transmittance rate and high in Verdet constant in a visible-near infrared region and a preparation method thereof. The crystal grows by a melt pulling method; the molecular formula is Tb(10-x)(SiO4)6O(3-1.5x), wherein x is equal to 0-2; the crystal belongs to a hexagonal crystal system, and the space group is shown in the specification. The magneto-optical crystal has a good magneto-optical effect, and the Verdet constant of the magneto-optical crystal is higher than that of the conventional commercially applied terbium-doped glass and terbium gallium game (TGG) crystals; meanwhile, at the waveband of 400-1,500nm except for 485nm where the magneto-optical crystal has a feature absorption peak of the Tb<3+> ion, the magneto-optical crystal has high transmittance rate at other waveband; particularly within the visible light waveband of 400-650nm, the transmittance rate of the magneto-optical crystal is obviously increased as compared with that of the TGG crystal, so that the magneto-optical crystal has a good application prospect when used as a magneto-optical material; furthermore, the magneto-optical is a congruent melting compound and can grow by an intermediate-frequency induction pulling method; the growth technology is simple, the period is short, and large-scale and low-cost batch production can be realized.

An optical sensor that senses current by directing polarized light across an airgap that is orthogonal to a direction of current running through a conductor. The sensor includes a prism having a high Verdet constant for high sensitivity to magnetic fields, which cause an angle of polarization of the polarized light to be rotated as an indication of the magnitude of current. A polarizing beamsplitter having a low Verdet constant is mounted to the prism so that incoming light that is traveling in a direction orthogonal to the magnetic field being sensed across the airgap is insensitive to unwanted magnetic fields produced by nearby conductors. The distance the light travels in this orthogonal direction is minimized, reducing the overall volume of the sensor, making a compact sensor highly sensitive to magnetic fields of interest, largely insensitive to unwanted magnetic fields, and having a very high dynamic range for sensing current.

The invention provides a scandium doped terbium aluminum garnet magneto-optical crystal and a preparation method thereof. The crystal has a chemical formula of Tb3ScxAl5-xO12 (x=1.0-1.5), belongs to cubic system, and has a space group shown as the specification. Crystals can employ czochralski method or guided mode czochralski method with high axial temperature gradient at a near growth interfacefor growth, and the method has the characteristics of strong operability, simple process and short cycle, and can achieve large-scale and low-cost batch production of large size single crystals. The prepared crystal has the advantages of large size, good optical homogeneity, excellent physical and chemical properties, large Verdet constant and high permeation performance in visible-near infrared regions. The crystal has strong magneto-optical effect in visible-near infrared regions, and the Verdet constant is about 20-30% higher than commercial TGG crystals. Orientation, cutting, rough grinding, polishing and film coating can be carried out on the crystal according to requirements to obtain various magneto-optical devices, the crystal can be widely applied in various magneto-optical fields, and has significant economic and social benefits.

The invention discloses a preparation method of bismuth-containing paramagnetic Faraday optical rotation glass. The preparation method comprises the following steps of: firstly, uniformly mixing Er2O3, Bi2O3, B2O3, Al2O3, SiO2, Sb2O3 and ZrO2 to obtain a batch; secondly, fusing the batch to obtain molten glass, dropping the molten glass into a graphite mould, thermally insulating at 550 DEG C for 3 hours, and cooling to room temperature to obtain the bismuth-containing paramagnetic Faraday optical rotation glass. According to the invention, the bismuth-containing paramagnetic Faraday optical rotation glass is prepared by adopting a fusing and pouring method, owing to bismuth oxide with large molecular weight and low melting point, a forming range of the glass is expanded and the fusing temperature is reduced. The prepared Faraday magneto-optical glass has high content of rare earth erbium oxide, excellent glass forming property, remarkable Faraday effect and large Verdet constant, and the test sample has high light transmittance in a visible light range, and excellent heat stability and chemical stability. The preparation process has the advantages of simple operation process, low founding temperature, small high-temperature viscosity in the glass fusing process, short fusing time, excellent forming property, low cost, energy conservation and environmental friendliness and is suitable for industrial production.

An optical module is provided that includes a Faraday rotator having a Verdet constant at a wavelength of 1.06 μm of at least 0.27 min/(Oe·cm), a first hollow magnet disposed on the outer periphery of the Faraday rotator, and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis. The second and third hollow magnet units include 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis. A magnetic flux density B (Oe) applied to the Faraday rotator is in the range of 0.5×10⁴≦B≦1.5×10⁴. The Faraday rotator is disposed on a sample length L (cm) in the range of 0.70≦L≦1.10, and has an external diameter D (cm) in the range of 0.20≦D≦0.60.

It is an object to provide a small-sized optical isolator that is suitable as an optical isolator used in a semiconductor laser used in applications such as medical treatment or optical measurement

The optical isolator for a wavelength band of 320 to 633 nm of the present invention comprises a Faraday device having a Verdet constant at a wavelength of 405 nm of at least 0.70 min/(Oe·cm), and a first hollow magnet disposed on the outer periphery of the Faraday device and second and third hollow magnet units disposed so as to sandwich the first hollow magnet on the optical axis, the second and third hollow magnet units comprising 2 or more magnets equally divided in a direction of 90 degrees relative to the optical axis, the Faraday device having applied thereto a magnetic flux density B (Oe) within the range of Expression (1) below, and a sample length L (cm) on which the Faraday device is disposed being within the range of Expression (2) below.

0.8×10⁴≦B≦1.5×10⁴  (1)

0.25≦L≦0.45  (2)