Simultaneous Faraday Research Articles

Enhanced Faraday rotation and magneto-optical figure of merit in gold grating/graphene/silicon hybrid magneto-plasmonic devices

Graphene is a promising THz magneto-optical material. However, high Faraday rotation is only achievable at a low THz frequency range in single layer graphene. In this paper, we report simultaneous Faraday rotation and optical transmission enhancement in Au grating/graphene/silicon hybrid plasmonic structures across a wide frequency range from 0.43 to 24 THz using extraordinary transmission of THz spoof surface plasmons. In a broad frequency range up to 13.1 THz, the Faraday rotation and magneto-optical figure of merit in this hybrid structure can exceed the maximum value of single layer graphene at the low THz frequency range. Numerical analysis on the device dispersion relation indicates that the mechanism of simultaneous Faraday rotation and transmission enhancement is due to coupling of the TE waveguide mode with the TM hybrid waveguide-plasmon mode. Our work demonstrates the hybrid plasmonic structure as a promising candidate for THz nonreciprocal photonic device applications.

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition.

Hybrid quantum systems integrating semiconductor quantum dots (QDs) and atomic vapours become important building blocks for scalable quantum networks due to the complementary strengths of individual parts. QDs provide on-demand single-photon emission with near-unity indistinguishability comprising unprecedented brightness—while atomic vapour systems provide ultra-precise frequency standards and promise long coherence times for the storage of qubits. Spectral filtering is one of the key components for the successful link between QD photons and atoms. Here we present a tailored Faraday anomalous dispersion optical filter based on the caesium-D1 transition for interfacing it with a resonantly pumped QD. The presented Faraday filter enables a narrow-bandwidth (Δω=2π × 1 GHz) simultaneous filtering of both Mollow triplet sidebands. This result opens the way to use QDs as sources of single as well as cascaded photons in photonic quantum networks aligned to the primary frequency standard of the caesium clock transition.

Faraday-effect polarimeter diagnostic for internal magnetic field fluctuation measurements in DIII-D.

Motivated by the need to measure fast equilibrium temporal dynamics, non-axisymmetric structures, and core magnetic fluctuations (coherent and broadband), a three-chord Faraday-effect polarimeter-interferometer system with fast time response and high phase resolution has recently been installed on the DIII-D tokamak. A novel detection scheme utilizing two probe beams and two detectors for each chord results in reduced phase noise and increased time response [δb ∼ 1G with up to 3 MHz bandwidth]. First measurement results were obtained during the recent DIII-D experimental campaign. Simultaneous Faraday and density measurements have been successfully demonstrated and high-frequency, up to 100 kHz, Faraday-effect perturbations have been observed. Preliminary comparisons with EFIT are used to validate diagnostic performance. Principle of the diagnostic and first experimental results is presented.

Improved electron density measurements at Jicamarca

[1] Taking into account the effects of electron Coulomb collisions, incoherent scatter (IS) radar cross sections for probing angles close to perpendicular to the magnetic field have been calculated and used to correct backscattered power profiles measured with the Jicamarca incoherent scatter radar so that they accurately represent the height variation of the ionospheric electron density. The corrected power profiles are compared with simultaneous Faraday rotation measurements of electron density. The profiles agree within the measurements uncertainties. This result improves electron density measurements at Jicamarca, since power measurements are less sensitive to clutter and interference than Faraday rotation measurements. The results can be used to correct Jicamarca long-term IS power measurements.

X-ray Faraday rotation and magnetic circular dichroism in an iron-platinum compound

X-ray Faraday rotation - the dispersive analogue of x-ray magnetic circular dichroism - has been measured near the platinum L edges of ferromagnetic disordered Fe3Pt using a simple new technique. We show that fractional x-ray intensity changes on magnetization reversal scale directly with the Faraday signal. The validity of the new approach as an alternative method for obtaining circular dichroism spectra is verified by performing simultaneous Faraday rotation and dichroism measurements, and comparing the results with Kramers-Kronig transforms.

Nightglow Measurements of 630.0 nm Line from Kolhapur, India and Their Association with TEC Enhancements.

Nightglow measurements of 630.0 nm emission line by high resolution tilting photometer have been compared with simultaneous Faraday rotation measurements of the ionosphere's total electron content (TEC) from ETS-II satellite (-130°E) at a low latitude station, KOLHAPUR (Geog. lat. 16.8°N, long. 74.2°E, dip lat. 10.6°N) in India. The preliminary observational data are presented and discussed for seven nights during March, 1989 and April, 1990. The comparative study shows that in general the airglow enhancements are associated with the night time enhancement in TEC. The airglow enhancement due to downward motion of the F layer during pre-dawn hours does not correlate with TEC fluctuations. Further, the time rate of change of content has been used to obtain rough estimate of the nightglow intensity level at the station. On comparisons 630 nm emission intensities computed from TEC values and those predicted by MSIS-86 (Hedin, 1987) and FAIM (Anderson et al., 1989) models show an accepted level of agreement. Results focus the coupling between airglow producing irregularities and TEC at low latitude ionosphere.

Megagauss Magnetic Field Profiles in Laser-Produced Plasmas

Measurement of spatial profiles of self-generated magnetic fields in Nd: glass-laser-produced pla$\stackrel{\mathrm{`}}{\mathrm{s}}$mas have been made with high temporal and spatial resolution (30 ps, 1.5 \ensuremath{\mu}m) by simultaneous Faraday rotation and interferometry using a Raman-shifted second-harmonic probe beam.

The observation of periodic ionospheric disturbances using simultaneous Faraday rotation and angle of arrival measurements

Observations of periodic fluctuations in electron content are complemented by simultaneous observations of fluctuatons in the angle of arrival of the signal. It is shown that the phase and amplitude relationships between those two sets of fluctuations can provide considerably more information on the nature of the disturbances. In the case of a travelling disturbance estimates of the horizontal wavelength and direction of travel may be obtained at a single observing station. The method also provides an indication of whether or not the observed disturbances are in fact travelling, a matter of some importance in interpreting periodic ionospheric fluctuations in terms of atmospheric gravity waves. Examples are given of which some confirm the presence of a travelling atmospheric wave and some do not.