Search results for "birefringence"
showing 10 items of 133 documents
Continuous-wave cavity ring-down polarimetry
2020
We present a new cavity-based polarimetric scheme for highly sensitive and time-resolved measurements of birefringence and dichroism, linear and circular, that employs rapidly pulsed single-frequency continuous wave (CW) laser sources and extends current cavity-based spectropolarimetric techniques. We demonstrate how the use of a CW laser source allows for gains in spectral resolution, signal intensity, and data acquisition rate compared to traditional pulsed-based cavity ring-down polarimetry (CRDP). We discuss a particular CW-CRDP modality that is different from intensity-based cavity-enhanced polarimetric schemes as it relies on the determination of the polarization rotation frequency du…
Modulational instability in resonant optical fiber with higher-order dispersion effect
2010
International audience; The modulational instability (MI) of an electromagnetic wave in a resonant optical fiber with a two-level system is investigated. In the normal dispersion regime, we find the occurrence of nonconventional MI sidebands which are induced by the two-level resonant atoms. We also observe that the MI gain spectra are suppressed by the higher-order dispersion effect in the anomalous dispersion regime.
Inverse task for evaluation of particle size distribution of polydisperse magnetic fluids
2010
AbstractThe method of inverse task was used to analyze three different physical phenomena. The particle size distributions were reconstructed from the magnetization curve, dynamic light scattering and magnetic birefringence relaxation data. The results thus obtained for one real magnetic fluid sample are different; they characterize the physical nature of the phenomena. All three methods may be used to determine intrinsic sample properties.
Propagation of Dyakonon Wave-Packets at the Boundary of Metallodielectric Lattices
2013
We rigorously analyze the propagation of localized surface waves that takes place at the boundary between a semi-infinite layered metal-dielectric (MD) nanostructure cut normally to the layers and a isotropic medium. It is demonstrated that Dyakonov-like surface waves (also coined dyakonons) with hybrid polarization may propagate in a wide angular range. As a consequence, dyakonon-based wave-packets (DWPs) may feature sub-wavelength beamwidths. Due to the hyperbolic-dispersion regime in plasmonic crystals, supported DWPs are still in the canalization regime. The apparent quadratic beam spreading, however, is driven by dissipation effects in metal. This work was supported by the Spanish Mini…
Laser spatial profile effects in measurements of impulsive molecular alignment
2005
0953-4075; We use a non-intrusive technique based on a polarization scheme to probe the periodic alignment of the CO2 and N2 molecules induced by a strong laser pulse linearly polarized. A weak probe field experiences the birefringence resulting from the alignment of the molecules. By comparing the probe depolarization signal with the numerical simulation of the time-dependent Schrödinger equation, it is possible to quantify the alignment of the molecular sample. The modelling takes into account the spatial profile of the pump intensity. It allows from the alignment signal to determine the onset of saturation due to ionization, despite the intrinsic saturation of the alignment arising for a…
Bloch wave theory of modulational polarization instabilities in birefringent optical fibers
1997
The modulational instability gain spectra, of an arbitrarily polarized intense pump wave that experiences periodic nonlinear polarization rotation in a birefringent optical fiber, are derived by Floquet analysis. The predictions of the linearized analysis are confirmed by numerical simulations of the coupled nonlinear Schr\"odinger equations.
Modulational instability processes in optical isotropic fibers under dual- frequency circular polarization pumping
2002
Experiments are presented showing that, under dual-frequency, circular polarization pumping, host modulational instability processes can be generated in a single-mode isotropic fiber by careful tuning of the frequency spacing between the pumps.
Generation of High-Repetition-Rate Dark Soliton Trains and Frequency Conversion in Optical Fibers
1998
Induced modurational polarization instability in birefringent fibers leads to trains of dark soliton-like pulses. Optimal large-signal cw and soliton frequency conversion is also analysed.
Manakov Polarization Modulation Instability in Normal Dispersion Optical Fiber
2014
We observed polarization modulation instability in the normal dispersion regime of randomly birefringent multi-km telecom optical fiber. The instability is pumped by two wavelength multiplexed and orthogonally polarized intense continuous lasers.
Uniaxial epsilon-near-zero metamaterials: from superlensing to double refraction
2014
We investigated optical properties of nanostructured metal-dielectric multilayered lattices under the conditions of epsilon-near-zero (ENZ), a concept derived from the effective-medium approach (EMA). We theoretically found that the periodic array of metallic nanolayers may exhibit either superlensing driven by broadband canalization from point emitters or single-polarization double refraction, and conventional positive as well as negative, even at subwavelength regimes. For the latter case, we formulated a modified EMA, and subsequently a generalized refraction law, that describes both refractive behaviors concurrently. The modal coupling of plasmonic lattice resonances, and nonlocality in…