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Second harmonic generation in nonlinear gyrotropic media in the form of epitaxial films of rare-earth iron garnets was investigated for the first time both experimentally and theoretically. The anisotropy of the process in a magnetic field, as well as the Faraday and Kerr effects were studied. In the nonlinear interaction case the Faraday effect was half that in the linear case. An expression was obtained for describing the Faraday and Kerr effects for the case of a nonlinear interaction involving a semiinfinite nonlinear gyrotropic medium and a nonlinear gyrotropic layer: a characteristic feature of these effects was a nonlinear coordinate dependence. The experimentally observed characteristics of the two effects were explained by a model allowing solely for the linear magnetooptic parameters of the medium. Possible mechanisms of the appearance of the nonlinearity in iron garnets in a magnetic field were analyzed.

A new type of AC current sensor utilizing Faraday effect is proposed. On a Faraday element (which is placed between a cross-nicol pair of polarizer) a stabilized DC bias magnetic field Hb is applied. The amplitude Iω of fundamental and I2ω of second harmonic waves (induced by the AC field Hx) exiting in the intensity of light emerging from the analyzer are phase-detected. The ratio R=I2ω/Iω gives the output signal. When Faraday rotation angles a(∝Hx) and θ(∝Hb) are so amall that higher terms such as a2 and θ2 are neglected, we obtain R=Hx/4Hb, which is independent of not only light intensity but also Verdet constant of the Faraday element. Experiments performed at 20∼100°C on FR-5 glass and Bi-substituted YIG Faraday elements supported this. The effect due to the nonlinear terms a2 and θ2 is calculated, agreeing with our experimental results.

The possibility of using the Faraday effect for the diagnostics of magnetic fields in a dense plasma is theoretically demonstrated. A procedure for measuring the plane of polariztion of the probing radiation is examined in detail, with account taken of the wave polarization and of the presence of plasma self-luminosity. A procedure for determining the spatial distribution of the magnetic field is described. A new three-channel polarointerferometer scheme is proposed. The idea behind the method is illustrated with reconstruction of the magnetic fields in a laser plasma as an example.

The frequency of the dark resonance in coherent population trapping experiments has been measured as a function of the degree of ellipticity and the intensity of the probe light. The results have been used to find the quantum limit of sensitivity of an optical magnetometer based on the nonlinear Faraday effect.

We demonstrate a type of chiral effect of an atomic medium. Polarization rotation of a probe beam is observed only when both a magnetic field and a linearly polarized coupling beam are present. We compare it with other chiral effects like optical activity, the Faraday effect, and the optically induced Faraday effect from the viewpoint of spatial inversion and time reversal transformations. As a theoretical model we consider a five-level configuration involving the cesium $D2$ transition. We use spin-polarized cold cesium atoms trapped in a magneto-optical trap to measure the polarization rotation versus probe detuning. The result shows reasonable agreement with a calculation from the master equation of the five-level configuration.

An optically scanning electromagnetic field probe system, consisting of an electro-optic or magneto-optic crystal substrate and a galvano scanner, has been developed for high speed, low-invasive measurement of electromagnetic field distribution. We present some examples of measurement of electric field distributions using a LiNbO3 crystal substrate and the probe system. We have also measured magnetic field distributions above an MSL using a magnetic garnet thin film in the gigahertz range.

Magnetooptical effects in the metal/dielectric heterostructure, consisting of a thin metallic layer with the array of parallel subwavelength slits and a uniform dielectric layer magnetized perpendicular to its plane, are investigated. Calculations, based on the rigorous coupled-wave analysis of Maxwell's equations, demonstrate that in such structures the Faraday and Kerr rotation can be significantly enhanced in the near infrared optical range. It is possible by varying thickness of the magnetic film to make Faraday rotation and transmittance peaks coincident and achieve the increase in the Faraday effect by more than an order of magnitude at the transmittance of 40-45%. It is shown that the excitation of the surface plasmon polaritons and quasi-guided TM- and TE- modes in the dielectric layer mostly governs the enhancement of the Faraday rotation.

Enhancement of the Faraday effect in multilayer structures is considered. The structures are treated as open resonators. It is shown that the angle of Faraday rotation can be represented as a product of two factors, the first one is determined by the bulk magnetooptical properties and the second is a Q-factor of the resonator. The enhancement of MO properties is illustrated by consideration of the Airy's partial waves in single MO slab. This approach is generalized to an arbitrary MO resonant structure and allows us to design scheme with "perfect" Faraday effect with rotation by 90deg and unitary transmission..

The Faraday effect is an extremely useful probe of magnetization dynamics on an ultrafast scale. However, the measured Faraday rotation is difficult to interpret in birefringent media. We investigate the link between magnetization and Faraday rotation by solving Maxwell's equations in a magnetically ordered, birefringent material. We find that the Faraday rotation can depend nonlinearly on the magnetization, meaning that symmetric magnetic oscillations may lead to asymmetric Faraday measurements. Furthermore, sample alignment becomes important-if the incident light is not polarized along a birefringence axis of the sample, the Faraday rotation may be strongly enhanced or weakened, and the interpretation of the magnetization amplitude may be wrong by an order of magnitude. (c) 2007 American Institute of Physics.

We present a theoretical study of the Faraday effect in hybrid magneto-plasmonic crystals that consist of Au-Co-Au perforated membranes with a periodic array of sub-wavelength holes. We show that in these hybrid systems the interplay between the extraordinary optical transmission and the magneto-optical activity leads to a resonant enhancement of the Faraday rotation, as compared to purely ferromagnetic membranes. In particular, we determine the geometrical parameters for which this enhancement is optimized and show that the inclusion of a noble metal like Au dramatically increases the Faraday rotation over a broad bandwidth. Moreover, we show that the analysis of the Faraday rotation in these periodically perforated membranes provides a further insight into the origin of the extraordinary optical transmission.

If dark matter consists of cold, neutral particles with a nonzero magnetic moment, then, in the presence of an external magnetic field, a measurable gyromagnetic Faraday effect becomes possible. This enables direct constraints on the nature and distribution of such dark matter through detailed measurements of the polarization and temperature of the cosmic-microwave background radiation.

The electric and magnetic vectors of a field is changed by their linear combination by vectors of the Faraday. At such replacement in a homogeneous space the Maxwell equations will be converted to a system of two independent equations about the Beltrami vortexs. Under these circumstances, Faraday?s each vector describes a total electromagnetic field of an ideal circular polarization. The mutual transformation of Faraday's different vectors emerges in nonuniform mediums and on boundaries of areas of a homogeneous space. The Faraday?s vectors were being rediscovered more than once at 20 century, however they have not found of wide application in the antenna theory and engineering. A purpose of my message is to show efficiency of application of Faraday's vectors to problems of investigation of polarizing, diffraction and others of the antenna performances.

In a material with large magneto-optical susceptibility, due to the Inverse Faraday Effect, circularly polarized optical pulses induce a pulsed magnetic flux. Alternatively, sufficiently intense optical pulses can induce a pulsed magnetic flux by means of ultrafast demagnetization of a metallic thin film or multilayer with a perpendicular magnetic anisotropy. The time varying magnetic flux may induce a transient electro-motive force and electric current in a conducting loop on the surface of the illuminated material. The latter current induces a transient magnetic field that can be used in various nanomagnetic processes. The magnetic field pulses due to the transient current appear to be too short for use in the magnetic field or spin-current induced precessional switching of magnetization. However, our calculations suggest that the magnetic field could lead to ultrafast switching of a nanomagnet overlaid on the surface of the conductor and demagnetized by the same optical pulse. In the case of photo-magnetic pulses due to the Inverse Faraday Effect, the switching direction could be controlled by the helicity of the optical pulse. We also demonstrate that the proposed device, which we call a Faraday Magneto-Optical Transformer, could be used as a Terahertz emitter.

We report on significant enhancement of the magnetooptical effects in gyrotropic systems of a metallic film perforated by subwavelength hole arrays and a uniform dielectric film magnetized perpendicular to its plane. Calculations, based on a rigorous coupled-wave analysis, demonstrate the Faraday and Kerr effect spectra having several resonance peaks in the near infrared range, some of them coinciding with transmittance peaks. Qualitative analysis revealed that magnetic polaritons being coupled magnetic-film waveguiding modes with surface plasmons play a crucial role in the observed effect., Comment: 10 pages, 3 figures

Digital holographic technique has been applied to analyze the distribution of polarization state of transmitted light at the object surface by use of orthogonally polarized reference beam produced by a flint glass fiber Faraday rotator. The object composed of a glass plate and a layered sellophane tape is employed and the polarization distribution over the object surface is analyzed. It is shown that the proposed system can be applied for the whole field analysis of polarization state.

We measure relative propagation delay between two orthogonally polarized pulses in long fibers in the presence of a weak axial magnetic field (~50μT). We find that the fiber birefringence modifies the Faraday polarization eigenstates, which became noncircular and wander in time.

We investigate an all-optical, pump-probe scheme for the polarization rotation of linearly polarized light in an atomic medium. A circularly polarized control light is shown to play the role of a static magnetic field via a Zeeman-like ac Stark interaction and to induce the optical Faraday rotation (OFR) of the probe light. As a model system, we consider a stationary atom with $nS\text{\ensuremath{-}}nP\text{\ensuremath{-}}nD$ level scheme without electronic or nuclear spin. In addition to OFR, we find that electromagnetically induced transparency for the three-level atom and circular dichroism also contribute to the polarization change. We characterize these three effects over different frequency ranges through an explicit calculation of the fractional transmission and the output polarization of the probe light. Our results are compared with the $nS\text{\ensuremath{-}}nP\text{\ensuremath{-}}(n+1)S$ scheme, which has been previously studied both theoretically and experimentally. We also compare the optically induced Faraday effect with the Faraday effect from a static magnetic field. We propose an experimental situation to test the theory and address the possibility of producing an atomic medium that is both optically active and transparent.

An optoelectronic effect based on Faraday or Kerr rotation and the quantum‐confined Stark shift is demonstrated. It is novel in that the degree of rotation is controlled by an electric field as opposed to a magnetic field. By applying an electric field to a quantum well structure, the Faraday rotation can be tuned into resonance, thereby varying the rotation angle of plane polarized light. We have observed a resonant rotation of 10° in GaAs at a magnetic field of 1 T. By applying a gate voltage of 2 V to a GaAs/AlGaAs superlattice structure, we observed a change in rotation of 1.3° at 2 K. The Faraday–Stark effect could be useful in electrically controlled light switches and high‐speed optical modulators.

We discuss the merits of low coherence interferometry to investigate the Faraday effect in a diluted magnetic semiconductor (DMS) crystal placed in one of the interferometer arm. We describe the combination of modulation effects due to the Farady effect in the DMS probe with the modulation due to a vibrating mirror in the interferometer. Essential for the measurement of the Verdet constant is the control of polarization in the two arms of the interferometer. We show that by watching the resulting spectra of the photodetected signal, clear distinction is possible between the circular and linear polarization of the input light.

In this work, a derivative of spectrum of polarization resonances in 5S{sub 1/2}-5D{sub 5/2} transitions of Rb atoms at different values of longitudinal magnetic field, which occurs due to the Faraday effect, was observed in a temperature controlled and magnetically shielded cell. The amplitude and spectral shape of Faraday resonances were investigated as a function of external magnetic field and the experimental results are described by a simple theoretical model.

The history of magneto-optical effects is first introduced. Then the types of magneto-optical effects are described, which include the varieties of the interactions of electromagnetic waves with magnetization or spins in solids. The physical origin of the magneto-optical effects is phenomenologically discussed. Both magnetic circular/linear birefringence and dichroism, and Void and Cotton–Mouton effects are discussed. Then, some representatives of magneto-optical materials of transmission (Faraday effect) and reflection (Kerr) types are described. Finally, the applications of magneto-optical effects are presented, which include the isolators, circulators, modulators, deflectors, magneto-optical imaging, field sensors, magneto-optical sensors, and magneto-optical recording and microwave waveguides. In particular, a recent development of magneto-optical recording is summarized, which highlights the various novel methods of increasing recording density. Keywords: magneto-optical effect; Faraday effect; Kerr effects; birefringence; cotton–mutton effect; magneto-optic modulator; magneto-optical sensor; magneto-optic memories; hybrid recording

We study the effect of Faraday rotation due to a homogeneous magnetic field on the polarization of the cosmic microwave background (CMB). Scalar fluctuations give rise only to parity-even E-type polarization of the CMB. However in the presence of a magnetic field, a non-vanishing parity-odd B-type polarization component is produced through Faraday rotation. We derive the exact solution for the E and B modes generated by scalar perturbations including the Faraday rotation effect of a uniform magnetic field, and evaluate their cross-correlations with temperature anisotropies. We compute the angular autocorrelation function of the B-modes in the limit that the Faraday rotation is small. We find that primordial magnetic fields of present strength around $B_0=10^{-9}$G rotate E-modes into B-modes with amplitude comparable to those due to the weak gravitational lensing effect at frequencies around $\nu=30$ GHz. The strength of B-modes produced by Faraday rotation scales as $B_0/\nu^2$. We evaluate also the depolarizing effect of Faraday rotation upon the cross correlation between temperature anisotropy and E-type polarization., Comment: 11 pages, 4 figures. Minor changes to match the published version

We examine the rotation of the plane of polarization for linearly polarized light rays by the weak gravitational field of an isolated physical system. Based on the rotation of inertial frames, we review the general integral expression for the net rotation. We apply this formula, analogue to the usual electromagnetic Faraday effect, to some interesting astrophysical systems: uniformly shifting mass monopoles and a spinning external shell., 10 pages; accepted for publication in Phys. Rev. D

Magneto-optic imaging (MOI) is a relatively new technology that produces analog images of magnetic flux leakage from surface and subsurface defects. An alternating current carrying foil serves as the excitation source and induces eddy currents in a conducting test specimen. Under normal conditions, the associated magnetic flux is tangential to specimen surface. Anomalies in the specimen result in generating a normal component of the magnetic flux density. The magneto-optic sensor produces a binary valued image of this anomalous magnetic field. The current system has two shortcomings. First, the presence of a textured background due to the domain structures in the sensor makes detection of third layer cracks and corrosion difficult. Second, the qualitative nature of the MO images does not provide a basis for making quantitative improvements to the MOI system. The availability of a theoretical model that can simulate the MOI system performance is extremely important for the optimization of the MOI sensor and hardware system. This paper presents a finite element model and its use in understanding the capabilities of the MOI system. In addition the paper also presents signal-processing methods for eliminating the background noise.

Carrier properties of n‐type InSb doped with tellurium at liquid nitrogen temperature have been estimated by means of transmission of a millimeter wave (119.3 GHz) propagating along a magnetic field up to 4 T. The information of carrier properties is obtained from the Faraday rotation arising from the difference between phase velocities of two circularly polarized components. The advantage of this method lies in the fact that it allows both the electron density and effective mass to be measured simultaneously.

Optical activity, like Faraday effect, is a rotation of the plane of polarization of propagating light in a medium and can be attributed to different sources with distinct signatures. In this note we discuss the effect of optical activity {\it{in vacuum}} due to Kaluza-Klein scalar field $\phi$, in the presence of an external electro-magnetic field. The astrophysical implication of this effect is indicated. We also point out the possibility of observing the same in laboratory conditions., Comment: Four Pages

A method of measuring the peak value of the Faraday rotation ΦF (hereafter referred to as the dynamic Faraday rotation) induced by an alternating magnetic field is described. It requires accurate measurement of the fundamental and the second harmonics of the photodetector currents. The sample is a (BiPrGdYb)3(FeAl)5O12 magneto‐optic garnet film prepared by liquid phase epitaxy. Using the presented method, we successfully measured the dynamic Faraday rotation in the garnet film at the near infrared wavelength 1.55 μm of the light beam. The result shows that Faraday rotation induced by an alternating magnetic field is proportional to ac current and decreases with increasing ac frequency. The method is simple, general, accurate, and can be used at any ac frequency. Experimental errors in our measurement are analyzed and an accuracy better than 2% can be obtained. Finally, some of the factors which may influence the measurement results are discussed.

The polarization maintaining capability of the birefringent fiber can be described in terms of its modal birefringence or beat length. The minimum length of fiber over which the state of polarization (SOP) comes back to its original value is called the beat length and the beat length of the PM fiber can be measured by altering the SOP of the light in the fiber by external means. One technique is to apply a strong magnetic field to the fiber to alter the SOP of the light. This technique is based on Faraday magneto-optic effect, discovered in 1845 by Michael Faraday. This technique is non-destructive. Simple and efficient and beat lengths of 2 mm and less have been measured which fulfil the requirements for currently available PM fibers. The experimental results are very comprehensive and promising and it has been proven that this technique has significant advantages over other techniques in terms of simplicity, versatility, productivity and practicality.

Based on the classical electromagnetic theories, the Faraday magnetooptic effect in a diamagnetic medium is independent of temperature. In this study the geometric compensation methods is adopted and closed loop current sensor with frame structure is designed and fabricated based on the Faraday effect in diamagnetic media using SF6 glass. With the closed loop optical current sensor the experimental investigation on AC/DC current sensing has been carried out. Some experimental results are obtained and the conclusions are given.

The evolution of Pauli matrices coefficients, known as Quaternions, of a Nd/sup 3+/ fibre subjected to a longitudinal magnetic field, that is, to Faraday effect, has been analysed. These parameters change with the electrical current which generates the magnetic field. The obtained values are in general similar to the theoretical ones, although some disagreements have been found, which could be explained by the influence of external parameters, as temperature, pressures or vibrations, by mistakes in the measurement devices (polarizers, retarders,...) or by another factor as optical activity.

Summary form only given. A central filament is assumed to be axially positioned inside a cylindrical shell collapsing by the Z-pinch effect. The cumulation (i.e. concentration) process is induced by generating a high magnetic field between the cylindrical shell and the filament. The initial magnetic field (of the order of few Mega gauss is generated by a circular polarized laser light)(CPLL). The inverse Faraday effect induces an axial magnetic field between the shell and the filament. Assuming a dissipationless approach, it is shown that this problem is equivalent to two point particles moving in a potential.

The three basic elements of a fiber current sensor are a coil wrapped around a current carrying conductor, a light source and a polarization analyzer. The Faraday effect causes the plane of polarization of the propagating light to be rotated by an amount proportional to the current being sensed. One method of improving the measurement of Faraday rotation is to induce enough circular birefringence into the fiber to cancel the effect of the induced linear birefringence. However, the most practical solution to this problem is the use of spun elliptically birefringence (SEB) fiber. These fibers are produced from highly linear birefringent "bow-tie" preforms which are spun during the drawing process resulting into elliptical birefringence.

In 1846 Michael Faraday observed that the polarization of light traversing a glass slab is altered by a longitudinal magnetic field. In 1898 Macaluso and Corbino were the first to study the Faraday effect (FE) of an atomic sodium vapor using resonance radiation. The resonant FE was quantitatively explained by Voigt in the early 20th century in terms of the Zeeman effect on a Lorentz oscillator. In the vicinity of absorption lines both absorptive and dispersive effects contribute to the FE, so that the emerging light is elliptically polarized and the Faraday rotation angle φF is defined as the rotation of the polarization ellipse with respect to the incoming polarization.

A convenient and general decomposition of the photon self-energy in a magnetized, but otherwise isotropic, medium is given in terms of the minimal set of tensors consistent with the transversality condition. As we show, the self-energy in such a medium is completely parametrized in terms of nine independent form factors, and they reduce to three in the long wavelength limit. We consider in detail an electron gas with a background magnetic field, and using finite temperature field theory methods, we obtain the one-loop formulas for the form factors, which are exact to all orders in the magnetic field. Explicit results are derived for a variety of physical conditions. In the appropriate limits, we recover the well-known semi-classical results for the photon dispersion relations and the Faraday effect. In more general cases, where the semi-classical treatment or the linear approximation (weak field limit) are not applicable, our formulas provide a consistent and systematic way for computing the self-energy form factors and, from them, the photon dispersion relations., Comment: Revtex, 27 pages

International audience; We demonstrate an enhancement of Faraday rotation in reflection geometry (polar Kerr effect) for semimagnetic quantum wells embedded in a semiconductor-metal optical cavity. The theory of light reflection and Faraday rotation in Multiquantum well heterostructures is developed and applied to fit the experimental results. The large Faraday rotation (54.4 degrees T-1) makes this structure suitable for use as magneto-optic layers in the Faraday microscopy of the magnetic flux pattern at the surface of superconducting films

We propose a new type of Faraday isolator with compensation of the azimuthally symmetric component of polarization distortions by means of magnetic field inhomogeneity. The depolarization was attenuated in experiments by a factor of 7.

Determination of magnetic anisotropy on perpendicular and longitudinal fields in most magneto-optical materials is usually essential in magnetic measurements. However, 3D information is still insufficient and may be misled due to only two spin vectors. The vacuum magneto-optical Faraday effect measurement (the transmission mode of magneto-optics technique) in an ultrahigh vacuum system, a new concept for the reconstruction of 3D magnetic anisotropy is introduced. The Faraday rotation in the ultrathin (magnetic film)/(optical crystal) system exhibits a polar plane oscillation as a function of incidence angle. The crystal birefringence is responsible for causing the oscillation. The Faraday rotation, which consists of crystal optics and magneto-optics, originates from the crystal and the ultrathin film, respectively. Alternatively, we clarify a debate that the easy axis of the Co/ZnO(0001) film is only located at the plane. Through the observation of the angle-dependent coercivity, the magnetic easy axis in the proposed multilayer structure including double anisotropy is proposed.

Nonlinear equations are derived relevant to describe the propagation of powerful electromagnetic fields launched within a plasma. The nonlinear generation of self-induced collective electromagnetic perturbations are obtained with matter lying in the relativistic regime. Our main result is the self-consistent treatment of the coupled equations between the pump and its self-induced fields. In particular, a mechanism is pointed out for self-generation of quasistatic magnetic field that is due to the relativistic ponderomotive force. This process is found to be more efficient to produce quasistatic magnetic fields, as confirmed by recent experiments, as compared to known effects such as the inverse Faraday effect. As an application, we investigate conditions for relativistic magnetic guiding of light to occur under the combined action of the self-induced density and magnetic field.

International audience; Magnetic fields in excess of 7 MG have been measured with high spatial and temporal precision during interactions of a circularly polarized laser pulse with an underdense helium plasma at intensities up to 1×10^19Wcm^-2. The fields, while of the form expected from the inverse Faraday effect for a cold plasma, are much larger than expected, and have a duration approaching that of the high intensity laser pulse (

A fiber optic pulsed magnetic-field sensor based on Faraday magneto-optic effect is described in this paper. Its dynamic range is better than 70 dB within the nonlinearity of 5 percent and its noise equivalent magnetic flux density is about 1.5 by 10 -6 T. By the method of frequency spectrum analyze, the frequency response characteristic of the sensor is measured and its -3dB bandwidth is about 200kHz. The experimental results indicate that the sensor can be used for pulsed magnetic field or current measurements.