155 research outputs found
Intensity noise-driven nonlinear fiber polarization scrambler
We propose and analyze a novel all-optical fiber optic polarization scrambler, based on the transfer via the Kerr
effect of the intensity fluctuations of an incoherent pump beam into polarization fluctuations of a copropagating,
frequency shifted signal beam in a randomly birefringent telecom fiber. Optimal signal polarization scrambling
results whenever the input signal and pump beams have nearly orthogonal states of polarizations. The nonlinear
polarization scrambler may operate on either cw or high-bit-rate pulsed signals
Nonlinear femtosecond pulse propagation in an all-solid photonic bandgap fiber
Nonlinear femtosecond pulse propagation in an all-solid photonic bandgap fiber is experimentally and numerically investigated. Guiding light in such fiber occurs via two mechanisms: photonic bandgap in the central silica core or total internal reflection in the germanium doped inclusions. By properly combining spectral filtering, dispersion tailoring and pump coupling into the fiber modes, we experimentally demonstrate efficient supercontinuum generation with controllable spectral bandwidth
All-optical sampling and magnification based on XPM-induced focusing
International audienceWe theoretically and experimentally investigate the design of an all-optical noiseless magnification and sampling function free from any active gain medium and associated high-power continuous wave pump source. The proposed technique is based on the co-propagation of an arbitrary shaped signal together with an orthogonally polarized intense fast sinusoidal beating within a normally dispersive optical fiber. Basically, the strong nonlinear phase shift induced by the sinusoidal pump beam on the orthogonal weak signal through cross-phase modulation turns the defocusing regime into localized temporal focusing effects. This periodic focusing is then responsible for the generation of a high-repetition-rate temporal comb upon the incident signal whose amplitude is directly proportional to its initial shape. This internal redistribution of energy leads to a simultaneous sampling and magnification of the signal intensity profile. This process allows us to experimentally demonstrate a 40-GHz sampling operation as well as an 8-dB magnification of an arbitrary shaped nanosecond signal around 1550 nm in a 5-km long normally dispersive fiber. The experimental observations are in quantitative agreement with numerical and theoretical analysis
Optical Peregrine soliton generation in standard telecommunications fiber
International audienceWe present detailled experimental and numerical results showing the generation and breakup of the optical Peregrine soliton in standard telecommunications fiber. The impact of non-ideal initial conditions is studied through direct cut back measurements of the longitudinal evolution of the emerging soliton dynamics, and is shown to be associated with the splitting of the Peregrine soliton into two subpulses
Universal spectral dynamics of modulation instability: Theory, simulation, experiment
A central process of nonlinear fibre optics is modulation instability (MI), where weak perturbations on a continuous wave are amplified to generate a parametric cascade of spectral sidebands. Although studied for many years, it has only been recently appreciated that MI dynamics can be described analytically by Akhmediev breather (AB) solutions to the nonlinear Schrdinger equation (NLSE) [1]. This has led to important results, including the first observation of the Peregrine Soliton [2]. AB theory has also shown that the spectral amplitudes at the peak of the MI gain curve yield a characteristic log-triangular spectrum, providing new insight into the initial phase of supercontinuum generation [3]. Here, we present a significant extension to this theory by generalising the analysis to describe spectral characteristics for arbitrary gain. Our new result also describes the dynamics of the spectral development, a process previously studied only via truncated models or numerical approaches [4]. We confirm our theory by simulations and experiments. ďż˝ 2011 IEEE
Polarization modulation instability in a Manakov fiber system
The Manakov model is the simplest multicomponent model of nonlinear wave theory: It describes elementary
stable soliton propagation and multisoliton solutions, and it applies to nonlinear optics, hydrodynamics, and
Bose-Einstein condensates. It is also of fundamental interest as an asymptotic model in the context of the
widely used wavelength-division-multiplexed optical fiber transmission systems. However, although its physical
relevance was confirmed by the experimental observation of Manakov (vector) solitons in a planar waveguide in
1996, there have in fact been no quantitative experiments confirming its validity for nonlinear dynamics other than
soliton formation. Here, we report experiments in optical fiber that provide evidence of passband and baseband
polarization modulation instabilities in a defocusing Manakov system. In the spontaneous regime, we also reveal
a unique saturation effect as the pump power increases. We anticipate that such observations may impact the
application of this minimal model to describe and understand more complicated phenomena in nature, such as
the formation of extreme waves in multicomponent systems
Peregrine soliton in optical fiber-based systems
International audienceWe 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
Temporal spying and concealing process in fibre-optic data transmission systems through polarization bypass
International audienceRecent research has been focused on the ability to manipulate a light beam in such a way to hide, namely to cloak, an event over a finite time or localization in space. The main idea is to create a hole or a gap in the spatial or time domain so as to allow for an object or data to be kept hidden for a while and then to be restored. By enlarging the field of applications of this concept to telecommunications, researchers have recently reported the possibility to hide transmitted data in an optical fibre. Here we report the first experimental demonstration of perpetual temporal spying and blinding process of optical data in fibre-optic transmission line based on polarization bypass. We successfully characterize the performance of our system by alternatively copying and then concealing 100% of a 10-Gbit s-1 transmitted signal.
Trapping polarization of light in nonlinear optical fibers: An ideal Raman polarizer
The main subject of this contribution is the all-optical control over the
state of polarization (SOP) of light, understood as the control over the SOP of
a signal beam by the SOP of a pump beam. We will show how the possibility of
such control arises naturally from a vectorial study of pump-probe Raman
interactions in optical fibers. Most studies on the Raman effect in optical
fibers assume a scalar model, which is only valid for high-PMD fibers (here,
PMD stands for the polarization-mode dispersion). Modern technology enables
manufacturing of low-PMD fibers, the description of which requires a full
vectorial model. Within this model we gain full control over the SOP of the
signal beam. In particular we show how the signal SOP is pulled towards and
trapped by the pump SOP. The isotropic symmetry of the fiber is broken by the
presence of the polarized pump. This trapping effect is used in experiments for
the design of new nonlinear optical devices named Raman polarizers. Along with
the property of improved signal amplification, these devices transform an
arbitrary input SOP of the signal beam into one and the same SOP towards the
output end. This output SOP is fully controlled by the SOP of the pump beam. We
overview the sate-of-the-art of the subject and introduce the notion of an
"ideal Raman polarizer"
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