Search results for "circular polarization"
showing 10 items of 62 documents
Optical magnetic circular dichroism in threshold photoemission from a magnetite thin film
2011
Threshold photoemission excited by polarization-modulated ultraviolet femtosecond laser light is exploited for phase-sensitive detection of magnetic circular dichroism (MCD) for a magnetite thin film. Magnetite (Fe(3)O(4)) shows a magnetic circular dichroism of ∼(4.5 ± 0.3) × 10(-3) for perpendicularly incident circularly polarized light and a magnetization vector switched parallel and antiparallel to the helicity vector by an external magnetic field. The asymmetry in threshold photoemission is discussed in comparison to the magneto-optical Kerr effect. The optical MCD contrast in threshold photoemission will provide a basis for future laboratory photoemission studies on magnetic surfaces.
Origin of Kerr effect: investigation of solutions by polarization dependent Z-scan
2020
This material is based upon work supported by the ERDF 1.1.1.1 activity project No. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”.
Spin-polarized photoelectrons resonantly excited by circularly polarized light from a fractional Ag film on GaAs(100)
2013
We demonstrate a finite spin polarization of photoelectrons emitted from GaAs(100) covered by a fractional Ag film. The photoemission yield shows a sharp maximum for intermediate coverage and the spin polarization increases with increasing laser intensity. Photoelectrons are excited by circularly polarized 100 fs laser pulses of 800 nm wavelength. We recorded the photoemitted electrons using a photoemission electron microscope combined with a Mott spin polarimeter. The spin polarization is analyzed in dependence on the excitation frequency and intensity and on the average thickness of the silver film. The results are explained by a model combining multiphoton photoemission and optical field…
Modulational instability processes in optical isotropic fibers under dual-frequency pumping
2001
Experiments are presented showing that under dual-frequency, circular polarization pumping, a host modulational instability processes can be generated in a single isotropic fiber, by carefully tuning the frequency spacing between the pumps.
Improved active fiber-based retroreflector with intensity stabilization and a polarization monitor for the near UV.
2021
We present an improved active fiber-based retroreflector (AFR) providing high-quality wavefront-retracing anti-parallel laser beams in the near UV. We use our improved AFR for first-order Doppler-shift suppression in precision spectroscopy of atomic hydrogen, but our setup can be adapted to other applications where wavefront-retracing beams with defined laser polarization are important. We demonstrate how weak aberrations produced by the fiber collimator may remain unobserved in the intensity of the collimated beam but limit the performance of the AFR. Our general results on characterizing these aberrations with a caustic measurement can be applied to any system where a collimated high-qual…
Multimodal nonlinear imaging of suspended carbon nanotubes using circular polarizations
2013
In this work, multimodal nonlinear microscopy of suspended CNTs using circular polarizations (CP) was reported. Significant variations in the SHG and THG signals of the CNTs between left hand circular polarization (LHCP) and right hand circular polarization (RHCP) were observed. The variations in the nonlinear signals can be associated to the unique properties of the CNTs such as chirality.
Polarization backward-wave four-wave mixing in BaTiO_3:Fe using the photovoltaic effect
1997
We report the first study to our knowledge of polarization backward-wave four-wave mixing in a BaTiO3:Fe crystal and compare the results of our measurements with the calculations performed within the model of photovoltaic charge transport. Two identically polarized pump waves and one orthogonally polarized signal wave are sent to a sample in a plane normal to the crystal’s C axis; a phase-conjugate wave with polarization identical to that of the signal wave is generated. With a 2-mm-thick sample a phase-conjugate reflectivity Rpc≈0.01 is reached; for a 1-cm-thick sample, amplified reflection should be possible.
Polarization attraction using counter-propagating waves in optical fiber at telecommunication wavelengths
2008
International audience; In this work, we report the experimental observation of a polarization attraction process which can occur in optical fibers at telecommunication wavelengths. More precisely, we have numerically and experimentally shown that a polarization attractor, based on the injection of two counter-propagating waves around 1.55 mu m into a 2-m long high nonlinear fiber, can transform any input polarization state into a unique well-defined output polarization state.
Vector π pulse soliton in coherent optical amplifiers
2007
We found a novel type of vector soliton pulse in a medium with linear loss and nonlinear gain from the coherent resonant interaction of light with two-level atoms exhibiting a degenerate upper state.
Generation and characterization of 06-THz polarization domain-wall trains in an ultralow-birefringence spun fiber
2007
Polarization domain-wall (PDW) trains have been generated at a repetition rate of 0.6 THz in an ultralow-birefringence spun optical fiber and measured by use of an adapted frequency-resolved optical gating technique. Characterization of the intensity and the phase of the PDW train shows complete switching between adjacent domains of counterrotating circular polarizations and directly confirms predictions based on numerical simulations of the incoherently coupled nonlinear Schrödinger equations.