160 research outputs found
Intermodal Four-Wave-Mixing and Parametric Amplification in km-long Fibers
We theoretically and numerically investigate intermodal four-wave-mixing in
km-long fibers, where random birefringence fluctuations are present along the
fiber length. We identify several distinct regimes that depend on the relative
magnitude between the length scale of the random fluctuations and the
beat-lengths of the interacting quasi-degenerate modes. In addition, we analyze
the impact of polarization mode-dispersion and we demonstrate that random
variations of the core radius, which are typically encountered during the
drawing stage of the fiber, can represent the major source of bandwidth
impairment. These results set a boundary on the limits of validity of the
classical Manakov model and may be useful for the design of multimode
parametric amplifiers and wavelength converters, as well as for the analysis of
nonlinear impairments in long-haul spatial division multiplexed transmission
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
A universal optical all-fiber omnipolarizer
Wherever the polarization properties of a light beam are of concern, polarizers and polarizing beamsplitters (PBS) are indispensable devices in linear-, nonlinear-and quantum-optical schemes. By the very nature of their operation principle, transformation of incoming unpolarized or partially polarized beams through these devices introduces large intensity variations in the fully polarized outcoming beam(s). Such intensity fluctuations are often detrimental, particularly when light is post-processed by nonlinear crystals or other polarization-sensitive optic elements. Here we demonstrate the unexpected capability of light to self-organize its own state-of-polarization, upon propagation in optical fibers, into universal and environmentally robust states, namely right and left circular polarizations. We experimentally validate a novel polarizing device-the Omnipolarizer, which is understood as a nonlinear dual-mode polarizing optical element capable of operating in two modes-as a digital PBS and as an ideal polarizer. Switching between the two modes of operation requires changing beam's intensity
Wavelength conversion and temporal compression of a pulse train using a dispersion oscillating fibre
International audienceWe demonstrate the generation of a picosecond pulse train taking advantage of the cross gain occurring in a dispersion oscillating fibre. The resulting frequency-converted signal is detuned by more than 20 nm from the pump and can be temporally compressed by a factor 2 compared to the input sinusoidal pump wave
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
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.
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