695 research outputs found
Photonic Hall Effect in ferrofluids: Theory and Experiments
An experimental and theoretical study on the Photonic Hall Effect (PHE) in
liquid and gelled samples of ferrofluids is presented. The ferrofluids are
aqueous colloidal suspensions of Fe(_{2})CoO(_{4}) particles, which can be
considered as anisotropic and absorbing Rayleigh scatterers.
The PHE is found to be produced by the orientation of the magnetic moments of
the particles, as is also the case for the Faraday effect. The dependence of
the PHE with respect to the concentration of the scatterers, the magnetic field
and the polarization of the incident light is measured in liquid and in gelled
samples and is compared to a simple model based on the use of a scattering
matrix and the single scattering approximation.Comment: 20 pages, 11 figures, submitte
Optical Current Sensors for High Power Systems: A Review
The intrinsic advantages of optical sensor technology are very appealing for high voltage applications and can become a valuable asset in a new generation of smart grids. In this paper the authors present a review of optical sensors technologies for electrical current metering in high voltage applications. A brief historical overview is given together with a more detailed focus on recent developments. Technologies addressed include all fiber sensors, bulk magneto-optical sensors, piezoelectric transducers, magnetic force sensors and hybrid sensors. The physical principles and main advantages and disadvantages are discussed. Configurations and strategies to overcome common problems, such as interference from external currents and magnetic fields induced linear birefringence and others are discussed. The state-of-the-art is presented including commercial available systems.info:eu-repo/semantics/publishedVersio
Seeing spin dynamics in atomic gases
The dynamics of internal spin, electronic orbital, and nuclear motion states
of atoms and molecules have preoccupied the atomic and molecular physics
community for decades. Increasingly, such dynamics are being examined within
many-body systems composed of atomic and molecular gases. Our findings
sometimes bear close relation to phenomena observed in condensed-matter
systems, while on other occasions they represent truly new areas of
investigation. I discuss several examples of spin dynamics that occur within
spinor Bose-Einstein gases, highlighting the advantages of spin-sensitive
imaging for understanding and utilizing such dynamics.Comment: Chapter in upcoming Review Volume entitled "From Atomic to Mesoscale:
The Role of Quantum Coherence in Systems of Various Complexities" from World
Scientifi
On Kottler's path: origin and evolution of the premetric program in gravity and in electrodynamics
In 1922, Kottler put forward the program to remove the gravitational
potential, the metric of spacetime, from the fundamental equations in physics
as far as possible. He successfully applied this idea to Newton's
gravitostatics and to Maxwell's electrodynamics, where Kottler recast the field
equations in premetric form and specified a metric-dependent constitutive law.
We will discuss the basics of the premetric approach and some of its beautiful
consequences, like the division of universal constants into two classes. We
show that classical electrodynamics can be developed without a metric quite
straightforwardly: the Maxwell equations, together with a local and linear
response law for electromagnetic media, admit a consistent premetric
formulation. Kottler's program succeeds here without provisos. In Kottler's
approach to gravity, making the theory relativistic, two premetric
quasi-Maxwellian field equations arise, but their field variables, if
interpreted in terms of general relativity, do depend on the metric. However,
one can hope to bring the Kottler idea to work by using the teleparallelism
equivalent of general relativity, where the gravitational potential, the
coframe, can be chosen in a premetric way.Comment: 72 pages latex with 6 figures; based on an invited talk given at the
Annual Meeting of the German Physical Society (DPG) in Berlin on 20 March
2015, Working Group on Philosophy of Physics (AGPhil); a short version will
be submitted to IJMP
Development of optical modulators for measurements of solar magnetic fields
The measurement of polarized light allows solar astronomers to infer the magnetic field on the Sun. The accuracy of these measurements is dependent on the stable retardation characteristics of the polarization modulators used to minimize the atmospheric effects seen in ground-based observations. This report describes the work by the Space Science Laboratory at Marshall Space Flight Center to improve two types of polarization modulators. As a result, the timing characteristics for both electrooptic crystals (KD*Ps) and liquid crystal devices (LCDs) have been studied and will be used to enhance the capabilities of the MSFC Vector Magnetograph
Research Studies on Advanced Optical Module/Head Designs for Optical Disk Recording Devices
The Annual Report of the Optical Data Storage Center of the University of Arizona is presented. Summary reports on continuing projects are presented. Research areas include: magneto-optic media, optical heads, and signal processing
Magnetic Field Sensor Based on a Combination of a Microfiber Coupler Covered with Magnetic Fluid and a Sagnac Loop
This paper proposes a novel magnetic field sensor based on a microfiber coupler (MFC) combined with a magnetic fluid (MF) in a Sagnac loop formed from a polarization maintaining fiber (PMF). Thanks to the small (~2.6μm) waist diameter of the MFC, the resulting interference is strongly influenced by the presence of the MF and this leads to the desirable high sensitivity of the structure to the applied magnetic field. The maximum magnetic field sensitivities of −100pm/mT and −488pm/mT have been experimentally demonstrated with the PMF lengths of 75cm and 20cm respectively in the range of magnetic field strengths from 0 to 200mT. The dependence of the magnetic field orientation on the performance of the proposed sensor was also examined. The proposed magnetic field sensor is advantageous for applications requiring higher sensitivity over a wide magnetic field range
- …