76 results about "Faraday rotation angle" patented technology

The invention discloses an integrated measurement device for atomic density and polarizability of alkali metal vapor. The device comprises a drive laser subsystem, a measuring and sensing unit subsystem and a detection unit subsystem, wherein the measuring and sensing unit subsystem has the function of providing a physical carrier and testing conditions for measurement of density and polarizability; the drive laser subsystem has the function of polarizing alkali metal atoms in an air chamber; and the detection unit subsystem has the functions of measuring a deflection angle of detection light under different testing conditions and calculating the deflection angle to obtain the atomic density and polarizability. According to the device, pumping light is generated to irradiate the air chamber by utilizing the drive laser subsystem, a fixed magnetic field is applied to generate a Faraday rotating angle in the measuring and sensing unit subsystem, the deflection angle of the detection light is measured by utilizing the detection unit subsystem, and finally the atomic density and polarizability are calculated through a data processor. The device has the characteristics of simple measurement system and high measurement accuracy and has important significance for improving the inertia of atoms and the magnetic field measurement sensitivity.

An optical apparatus which is reduced in the number of optical devices arranged on a main optical signal transmission path, thereby reducing the size and cost of the device, and which is improved in optical transmission quality. An optical amplifier includes an amplification medium, which is doped with an active material for optical amplification and to which pump light is introduced, for amplifying an optical signal to be output. A reflection-type variable optical attenuator includes a reflecting mirror for reflecting an input light to generate a reflected light, and a magneto-optical crystal arranged in a position where the input and reflected lights pass. The magneto-optical crystal is applied with a magnetic field to induce a Faraday rotation angle therein and thereby vary an attenuation amount of the amplified optical signal, and part of light transmitted through the reflecting mirror is converted, as input monitor light, into an electrical signal.

The invention discloses an optical fiber current sensing method used for monitoring subway stray current and a sensing device thereof. Light-transmitting parts and sensing parts in the optical fiber current sensing device adopted by the invention are connected by all-fiber. The measurement results of the existing subway stray current monitoring method which is based on polarization potential monitoring are affected by factors and evaluated in a non-directviewing way. The invention is based on faraday effect, utilizes polarization property of optical fiber and indirectly measures current by measuring faraday rotation angle in the optical fiber, thereby overcoming the disadvantages of the traditional stray current monitoring method. The method has the prominent advantages that system test sensitivity can be adjusted according to specific conditions so as to be suitable for measuring current with different ranges. In the invention, the all-fiber is used for transmitting, thereby ensuring simple light path and good insulating property; closed circuit integral of a magnetic filed generated by current is detected by the sensing device, so that the measurement results are difficult to be affected by a stray field; the measurement frequency band is wide, and the dynamic range is wide, therefore, the invention has good project application prospect.

The invention provides a method for estimating a Faraday rotation angle (FRA) in satellite borne complete polarization synthetic aperture radar (SAR) data. The technical scheme comprises that the method comprises the steps of using measurement vector quantity of a satellite borne complete polarization SAR scattering matrix as input, (1) obtaining a polarimetric covariance matrix (PCM), obtaining the corresponding PCM of the measurement vector quantity according to the measurement vector quantity of the scattering matrix, (2) constructing a complex number for estimating the FRA, constructing the complex number relevant to the FRA through a real part of a non-diagonal element of the corresponding PCM of the measurement vector quantity and a diagonal element of the corresponding PCM of the measurement vector quantity, (3) estimating the FRA, and achieving the FRA estimation through the fact that the operations of angle taking and angle halving are carried on the complex number constructed in the step (2). The method for estimating the FRA of the satellite borne complete polarization SAR data is essentially free of influences of unbalanced system phases and steady in property.

The invention relates to an optical device for polarizing light by changing its Faraday rotation angle, such as optical attenuators, optical switches or polarization controllers; and its object is to provide such an optical device which can be driven even by small-sized and power-saving magnetic circuits and in which the insertion loss in the Faraday rotator may be reduced. The optical device comprises a Faraday rotator formed of a garnet single crystal, and a magnetic circuit applying an external magnetic field H that is smaller than the saturation magnetic field Hs of the Faraday rotator to the Faraday rotator.

The invention discloses a method for calibrating long-wavelength satellite-borne CTLR-mode compact-polarized SAR. The method comprises the following steps of: 1, acquiring an estimated value of an unbalanced error of a receiving channel; 2, acquiring an estimated value of a crosstalk coefficient of a circular-polarized transmitting channel; 3, acquiring an estimated value of a crosstalk coefficient of a linear-polarized receiving channel; 4, acquiring an estimated value of a Faraday rotation angle; and 5, acquiring an unambiguous estimated value of the Faraday rotation angle by using total electron content (TEC) data of a global navigation satellite system (GNSS) to finish SAR calibration. By the method, the processing process is simple and the processing precision is high; and the application of the method in processing of the long-wavelength satellite-borne CTLR-mode compact-polarized SAR data represented by a P wave band is very important.

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

The invention discloses a method for calibrating a compact polarimetric SAR (Synthetic Aperture Radar) in a long wave-length spaceborne pi/4 mode. The method comprises the following steps: 1, acquiring an estimation value of the degree of unbalancedness of a transmission channel; 2, acquiring an estimation value of a channel crosstalk coefficient of a vertical-launching horizontal-receiving component; 3, acquiring an estimation value of a Faraday rotation angle; 4, acquiring an estimation value of an unambiguous Faraday rotation angle by utilizing TEC (Total Electron Content) data provided bya global navigation satellite system; 5, acquiring an estimation value of the degree of unbalancedness of a receiving channel; and 6, acquiring an estimation value of a channel crosstalk coefficient of a horizontal-launching vertical-receiving component. By utilizing the method, accurate calibration still can be performed without scaler errors or system noise, and high-precision calibration can still be performed when the scaler errors and system noise exist. The method provided by the invention has important application value in processing the compact polarimetric SAR data in the long wave-length spaceborne pi/4 mode represented by a P wave band.

The present invention relates to a magnetooptical device utilizing a magnetooptical effect provided by using a magnetic garnet material, and provides a magnetic garnet material which is less likely to crack during the growth and lapping of the single crystal film. It is an object of the invention to provide a magnetooptical device which defines a Faraday rotation angle theta expressed by 44 deg.<=theta<=46 deg. when light having a wavelength lambd (1570 nm<=lambd<=1620 nm) impinges thereupon, in order to permit the suppression of and which is less likely to crack during processing to allow any reduction of yield. A magnetic garnet material expressed by a general formula: BiaM13-aFe5-bM2bO12 is used. M1 is at least one kind of element that is selected from among Y, La, Eu, Gd, Ho, Yb, Lu and Pb; M2 is at least one kind of element that is selected from among Ga, Al, Ti, Ge, Si and Pt; and a and b satisfy 1.0<=a<=1.5 and 0<=b<=0.5, respectively.

The invention discloses an all-fiber optical current transformer detection system. The all-fiber optical current transformer detection system comprises a sensing optical fiber ring, a light path system, a circuit system and a merging unit; the sensing optical fiber ring is used for acquiring a current signal of a to-be-detected position and generating a light intensity signal carrying data information of a Faraday rotation angle; the light path system is used for transmitting the data information to the circuit system by virtue of the optical fiber; the circuit system is used for receiving data information transmitted by the light path system and converting the data information to a circuit digital signal; the merging unit is used for receiving the circuit digital signal generated by the circuit system and outputting an identification signal. The current transformer adopts a special optical fiber winding way, so that the temperature drift can be effectively inhibited, the influence of the birefringence phenomenon on detection precision of an ordinary optical fiber transformer can be overcome, the birefringence phenomenon is influenced by the temperature, so that the precision drift of the detection precision caused along with the temperature variation exists.

An imaging capturing apparatus comprising, a light source, a polarizing beam splitter configured to illuminate a target with light from the light source, a sensor configured to capture an image of the inspection target by incidence of light reflected from the target through the polarizing beam splitter, and a Faraday rotator provided between the polarizing beam splitter and the target and disposed away from the polarizing beam splitter such that a Faraday rotation angle in the polarizing beam splitter is within a range of an angle equal to or larger than −0.5 degrees and an angle equal to or smaller than 0.5 degrees.

The invention provides an all-optical-fiber current transformer and a current measuring method thereof. The all-optical-fiber current transformer is mainly formed by three parts: a sensing unit, a signal processing unit, and a merging unit. The sensing unit employs the Faraday magneto-optic effect principle and used for inducing current of a measured conductor, and generating light intensity signals carrying data information of the Faraday rotation angle. The signal processing unit mainly completes input of optical singles of the sensing unit, analysis of the output optical signals, digitalization processing, and temperature compensation etc., and performs output according to a prescribed synchronous serial mode. The merging unit completes synchronization, switching or parallel logic of information of the signal processing unit, and transmits the information to an electrical measuring instrument and a relay protection device.

By making the beam polarization state in a cross prism having a dichroic function for an incident beam on a reflection type liquid crystal panel the same as that for a reflected ON beam, a small-sized, low cost projection type projector apparatus is provided. A Faraday rotator having a Faraday rotation angle of 45 degrees is disposed on an optical path between a PBS and a cross prism. A half-wave plate having such a polarization axis as to rotate a polarization angle of linearly polarized light by 45 or 135 degrees is disposed on an optical immediately before or behind the Faraday rotator.

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.

Optical devices including a Faraday rotation devices improved in wavelength and temperature characteristics and an optical attenuator reduced in wavelength dependence and temperature-dependent loss. The Faraday rotation device has permanent magnets magnetized in an axial direction of through-holes, and Faraday elements having a same Faraday rotation direction with respect to a same magnetization direction. The permanent magnets are directed in the same magnetization direction along an optical path, where part of the Faraday elements are accommodated in the through-hole of the permanent magnet, and the remaining Faraday elements are arranged between the magnets, whereby the Faraday elements are to be applied by magnetic fields in opposite directions. For a device variable in Faraday rotation angle, an electromagnet is provided. An input fiber collimator and polarizer are provided on an input side of with the Faraday elements while an analyzer and output fiber collimator are on an output side.

A reflection-type variable optical attenuator comprises: a main attenuator unit including a first birefringent crystal plate, a Faraday rotational angle varying unit, and a second birefringent crystal plate arranged in this order; an input port and an output port that are arranged on a side of one end of the main attenuator unit; and a two-point reflection-type optical path varying reflector that is arranged on a side of the other end of the main attenuator unit. Light that comes in from the input port makes a round trip in the main attenuator unit and goes out through the output port.

The present invention provides a single crystal for an optical isolator having a Faraday rotation angle exceeding that of TGG single crystal in a wavelength region of 1064 nm or longer or in a wavelength region of shorter than 1064 nm, and is capable of realizing enlargement of crystal size, a production process thereof, an optical isolator, and an optical processor that uses the optical isolator. The single crystal according to the present invention is composed of a terbium aluminum garnet single crystal, and mainly a portion of the aluminum is replaced with lutetium.

The present invention discloses a fully-polarized high-orbit SAR (synthetic aperture radar)-based ionized layer time-varying TEC (total electron content) measurement method. The method includes the following steps of: step 1, azimuth synthetic aperture point number calculation; step 2, azimuth data zero filling; step 3, azimuth Fourier transformation; step 4, azimuth signal decompression to obtainequivalent azimuth echo spectrum signals; step 5, azimuth inverse Fourier transformation; step 6, Faraday rotation angle estimation; and step 7, time-varying TEC acquisition during synthetic aperturetime. By means of the above seven steps, fully-polarized high-orbit SAR signals are utilized to complete the precise measurement of the time-varying TEC during the synthetic aperture time. The methodof the invention has high time-varying TEC measurement accuracy. Since a Faraday rotation angle model and a TEC inversion model are adopted, the method has higher measurement accuracy compared with atraditional measurement method.

The invention relates to an optoisolator for use in fiber-optic communication, which is characterized in that: a positive polarization state control component, an insulator component and a negative polarization state control component are parallelly arranged along a light transmission direction in turn; the positive polarization state control component is comprised of a first linear polarizer and a first quarter wave plate, which are parallelly arranged along the light transmission direction in turn; the isolator component is comprised of a first high-reflectivity reflector, a Faraday rotator, a second high-reflectivity reflector and a permanent magnet, which are parallelly arranged along the light transmission direction in turn; and the negative polarization state control component is comprised of a second quarter wave plate and a second linear polarizer, which are parallelly arranged along the light transmission direction in turn. The optoisolator has the advantages that: the change in a Faraday rotation angle does not deteriorate the performance of the optoisolator seriously, so the requirements on the temperature stability of Faraday magneto-optic materials are lowered; a 40 to 65dB or above isolation degree requirement can be met by simply using single-stage isolation; and light beams do not displace transversely, the light path is short, and the miniaturization of elements can be realized.