Search results for "optical"
showing 10 items of 7671 documents
Regions of Existence and Transformations of (3+1)-D Dissipative Optical Solitons
2006
We demonstrate the existence of stable optical light bullets in nonlinear dissipative media featuring both normal and anomalous chromatic dispersion. Beyond the domain where stable bullets are found, unstable bullets can be transformed into "rockets".
Peregrine soliton in optical fiber-based systems
2011
International audience; We report the first observation in optics of the Peregrine soliton, a novel class of nonlinear localized structure. Two experimental configurations are explored and the impact of non-ideal initial conditions is discussed.
Numerical Maps for Fiber Lasers Mode Locked with Nonlinear Polarization Evolution: Comparison with Semi-Analytical Models
2008
We have used a fully vectorial model based on two coupled nonlinear Schrodinger equations to study mode locking and pulse generation initiated and stabilized by nonlinear polarization evolution in a stretched pulse, double-clad, Yb-doped, fiber laser. The model takes explicitly into account gain saturation, finite amplification bandwidth, Kerr-induced self- and cross-phase modulations, group velocity dispersion, polarization control, and linear birefringence. Complete maps versus the orientation of intra-cavity wave-plates have been established. They comprise a large variety of pulse regimes that can be simply obtained by turning the intracavity wave-plate: stable single pulse per round tri…
Light-by-light polarization control and stabilization in optical fibers for telecommunication applications
2012
With the advent of future transparent ultra high-bit rate capacity transmission networks, encoding the data would necessary involve all the physical parameters of a light beam, including multi-level in intensity, phase, polarization and even propagation modes. These complex optical fields will then naturally suffer from strong impairments imposed by linear and nonlinear propagation effects. Hence, developing new all-optical tools able to control or regenerate any properties of light has become of a crucial interest. In this work, we experimentally report that it is possible, using a unique segment of optical fiber, to all-optically manipulate and regenerate both the state of polarization (S…
Statistical analysis of pulse propagation driven by polarization-mode dispersion
2002
International audience; The linear propagation of pulses driven by random polarization-mode dispersion is considered. Analytical expressions are derived for the probability-density functions of the pulse width, timing displacement, and degree of polarization. The study is performed in Stokes space, and frequency correlation between modes is shown to play an important role in it.
Nonlinear spectral compression in optical fiber: A new tool for processing degraded signals
2017
International audience; We propose two new applications of the spectral focusing by self-phase modulation that occurs in a nonlinear optical fiber. We numerically show the possibility of using nonlinear spectral compression to improve the optical signal to noise ratio and mitigate the amplitude jitter of the signal pulses. We also demonstrate experimentally that use of spectral focusing in a combination with an external sinusoidal phase modulation achieves efficient suppression of coherent spectral background.
Spectral phase reconstruction of femtosecond laser pulse from interferometric autocorrelation and evolutionary algorithm
2021
International audience; We report on the complete temporal characterization of femtosecond laser pulses from second-order interferometric autocorrelation and laser spectrum measurements. The method exploits a newly developed autocorrelator based on a two photon-absorption signal produced directly within a camera sensor so as to provide a single-shot interferometric autocorrelation of great reliability and robustness. Interferometric autocorrelation trace and laser spectrum are exploited for a spectral phase retrieval via an evolutionary algorithm. The quality of the reconstruction for highly modulated spectral phases imprinted by a pulse shaper confirms the reliability of the method. The au…
Near-field control of optical bistability in a nanocavity
2009
Micro- and nanocavities allow for strong light confinement in very small volume [1]. They give opportunities for new experiments such as cavity quantum electrodynamics, waveguiding, light slowing or trapping…[2] The increase of the electromagnetic (EM) field in the cavity enhances the interaction between light and matter, resulting in the possible observation of nonlinear effects [3]. Several studies have recently been published on the observation and characterisation of nonlinear silicon cavities [4]. As a step further, we propose and demonstrate the feasibility of an innovative way to mechanically control the bistable operating regime of a nanovavity. Using a near-field tip, we switch the…
Pulse timing effects in bulk Er/Yb codoped diode-pumped eyesafe lasers
2007
In this work, diode-pumping with appropriately modulated pulses is used to expose subtle input / output pulse-timing characteristics of Er3+ /Yb3+ systems, study their relation to laser efficiency and demonstrate some unique laser-pulse timing behavior. Er+3/Yb+3 codoped glass and YAG laser-host materials with similar concentrations (optimized for eyesafe emission in the 1.6-mum region) were studied in the same diode-pumped setup, in similar resonator configurations and analogous operating conditions.
Coupled experiment/simulation approach for the design of radiation-hardened rare-earth doped optical fibers and amplifiers
2011
We developed an approach to design radiation-hardened rare earth -doped fibers and amplifiers. This methodology combines testing experiments on these devices with particle swarm optimization (PSO) calculations. The composition of Er/Yb-doped phosphosilicate fibers was improved by introducing Cerium inside their cores. Such composition strongly reduces the amplifier radiation sensitivity, limiting its degradation: we observed a gain decreasing from 19 dB to 18 dB after 50 krad whereas previous studies reported higher degradations up to 0°dB at such doses. PSO calculations, taking only into account the radiation effects on the absorption efficiency around the pump and emission wavelengths, co…