Search results for "birefringence"
showing 10 items of 133 documents
Generation of vector dark-soliton trains by induced modulational instability in a highly birefringent fiber
1999
International audience; We present a set of experimental observations that demonstrate the generation of vector trains of dark-soliton pulses in the orthogonal axes of a highly birefringent optical fiber. We generated dark-soliton trains with terahertz repetition rate in the normal group-velocity dispersion regime by inducing a polarization modulational instability by mixing two intense, orthogonal continuous laser beams. Numerical solutions of the propagation equations were used to optimize the emission of vector dark pulses at the fiber output.
Modulational Instability and Stimulated Raman Scattering in Normally Dispersive Highly Birefringent Fibers
2001
Abstract The nonlinear interaction of two laser beams in normally dispersive highly birefringent optical fibers leads to a large set of fascinating physical effects such as modulational instability (MI) and stimulated Raman scattering (SRS). These two nonlinear phenomena have a positive role as a mechanism for the generation of short optical pulses and represent a drawback in fiber-optics transmissions. Indeed, we will show that an induced process of modulational instability may be exploited for the generation of THz train of vector dark solitons. The technique of frequency-resolved optical gating is used to completely characterize the intensity and phase of the dark soliton trains. On the …
Dark three-sister rogue waves in normally dispersive optical fibers with random birefringence
2014
11 pags.; 4 figs.; OCIS codes: (190.3100) Instabilities and chaos; (190.4370) Nonlinear optics, fibers; (060.5530) Pulse propagation and temporal solitons.
Large-signal enhanced frequency conversion in birefringent optical fibers: theory and experiments
1998
Strong frequency conversion among light waves propagating in a low-birefringence optical fiber in the normal-dispersion regime is experimentally investigated. Modulational gain spectra are obtained by injection of a signal orthogonally polarized with respect to a pump beam aligned with the slow fiber axis. Measurements reveal that, for signal power levels above a certain threshold value, peak conversion is obtained at pump signal frequency detunings far from the phase-matching condition. The large-signal three-wave mixing regime is well described by integrable nonlinear coupled-wave equations.
<title>Polarization-optical visualization of eye inhomogeneities</title>
2000
Polarization sensitive technique is reported for visualization of eye scattering and birefringent inhomogeneities using digital subtracting of eye images captured by a CCD camera for two orthogonal polarizations of light forming images in the CCD camera. For fast capturing of images the polarization plane of the backscattered light is periodically switched at 90 degrees by an electro-optical PLZT phase plate. This plate is placed close to the CCD camera together with a sheet polarizer inserted between camera and the phase plate. Polarization plane is switched applying the voltage 1200 V to the phase plate at a rate of 7.5 Hz. The technique improves visualization due to diminishing of the im…
Dark-soliton-like pulse-train generation from induced modulational polarization instability in a birefringent fiber
1998
Theory and experiments show that the nonlinear development of the modulational polarization instability of an intense light beam in a normally dispersive, low-birefringence optical fiber leads to ultrashort dark-soliton-like trains with repetition rates in the terahertz range in the polarization orthogonal to the pump.
Transmission and phase measurement for polarization eigenvectors in twisted-nematic liquid crystal spatial light modulators
1998
Recently we published theoretical expressions for the eigenvalues and eigenvectors for a twisted-nematic liquid crystal spatial light modulator (LCSLM) as a function of the twist angle and birefringence using the Jones matrix formalism. These polarization eigenvectors are of interest for newer video graphics adapter (VGA) resolution (640 3480 pixels) LCSLMs that are thinner and consequently have a lower birefringence. Although these devices can produce excellent amplitude modulation, they cannot achieve phase-only modulation using linearly polarized light. In these cases, the polarization eigenvectors are required to obtain phase-only modulation. We present experimental measurements for bot…
Modulational instability and critical regime in a highly birefringent fiber
1996
We report experimental observations of modulational instability of copropagating waves in a highly birefringent fiber for the normal dispersion regime. We first investigate carefully the system behavior by means of nonlinear Schr\"odinger equations and phase-matching conditions, and then, experimentally, we use two distinct techniques for observing MI (modulational instability) in the fiber; namely, the single-frequency copropagation, where two pump waves of identical frequency copropagate with orthogonal polarizations parallel to the two birefringence axes of the fiber, and the two-frequency copropagation, where the two polarized waves copropagate with different frequencies. In both cases …
Field-free molecular alignment of CO2 mixtures in presence of collisional relaxation
2008
The present work explores the extension of the concept of short-pulse-induced alignment to dissipative environments within quantum mechanical density matrix formalism (Liouville equation) from the weak to the strong field regime. This is illustrated within the example of the CO2 molecule in mixture with Ar and He, at room temperature, for which a steep decrease of the alignment is observed at moderate pressure because of the collisional relaxation. The field-free alignment is measured by a polarization technique where the degree of alignment is monitored in the time domain by measuring the resulting transient birefringence with a probe pulse Raman induced polarization spectroscopy (RIPS) Co…
Intensity noise-driven nonlinear fiber polarization scrambler
2014
We propose and analyze a novel all-optical fiber polarization scrambler based on the transfer (via the Kerr effect) of the intensity fluctuations of an incoherent pump beam into polarization fluctuations of a frequency-shifted signal beam, copropagating in a randomly birefringent telecom fiber. Optimal signal polarization scrambling results whenever the input signal and pump beams have nearly orthogonal states of polarization. The nonlinear polarization scrambler may operate on either cw or high-bit-rate pulsed signals.