63 research outputs found
Nonlinear polarizers based on four-wave mixing in high-birefringence optical fibers
Parametric amplification or four-wave mixing in high-birefringence optical fibers may be exploited to implement a novel type of nonlinear polarizer. Such a device leads to the simultaneous amplification, frequency conversion, and repolarization of both signal and idler waves along one of the principal birefringence axes of the fiber, independently of the pump, signal, and idler input state of polarization, power, and frequency detuning. We discuss the conditions for the observation of polarization attraction in fiber optics parametric amplifiers operating with a pump in either the normal or the anomalous dispersion regime
Complex dispersion relation of a double chain of lossy metal nanoparticles
International audienceWe study the propagation characteristics of optical signals in waveguides composed of a double chain of metallic nanoparticles embedded in a dielectric host. We find that the complex Bloch band diagram for the guided modes, derived by the Mie scattering theory including material losses, exhibits strong differences with respect to the previously studied single chain. The results of the model are validated through finite element solution of Maxwell's equations
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
Self-Repolarization process in dual-Omnipolarizers
We report on an extension of the concept of nonlinear self-repolarization
process by means of two different architectures based on dual-Omnipolarizers.
More specifically, we compare the performance in terms of polarization
attraction capabilities provided by two novel arrangements: The first
configuration relies on two cascaded Omnipolarizers, whilst the second
architecture integrates an additional device directly into the feedback loop.
Our study reveals that for a constant power budget, the cascading of two
subsequent Omnipolarizers enables to improve the efficiency of the attraction
process, yielding an output Degree-of-Polarization close to unity, but at the
cost of twofold equipments
Light propagation in nonuniform plasmonic subwavelength waveguide arrays
International audienceWe study light propagation in nanoscale periodic structures composed of dielectric and metal in the visible range. We demonstrate that diffraction curves of nonuniform waveguide arrays can be tailored by varying the geometric and dielectric features of the waveguides. The results obtained from a proper formulation of Coupled Mode Theory for non uniform arrays are validated through numerical solution of Maxwell equations in frequency domain
Fast and Chaotic Fiber-Based Nonlinear Polarization Scrambler
International audienceWe report a simple and efficient all-optical polarization scrambler based on the nonlinear interaction in an optical fiber between a signal beam and its backward replica which is generated and amplified by a reflective loop. When the amplification factor exceeds a certain threshold, the system exhibits a chaotic regime in which the evolution of the output polarization state of the signal becomes temporally chaotic and scrambled all over the surface of the Poincaré sphere. We numerically derive some design rules for the scrambling performances of our device which are well confirmed by the experimental results. The polarization scrambler has been successfully tested on a 10-Gbit/s On/Off Keying Telecom signal, reaching scrambling speeds up to 500-krad/s, as well as in a wavelength division multiplexing configuration. A different configuration based on a following cascade of polarization scramblers is also discussed numerically, which leads to an increase of the scrambling performances
Mode attraction, rejection and control in nonlinear multimode optics
Novel fundamental notions helping in the interpretation of the complex
dynamics of nonlinear systems are essential to our understanding and ability to
exploit them. In this work we predict and demonstrate experimentally a
fundamental property of Kerr-nonlinear media, which we name mode rejection and
takes place when two intense counter-propagating beams interact in a multimode
waveguide. In stark contrast to mode attraction phenomena, mode rejection leads
to the selective suppression of a spatial mode in the forward beam, which is
controlled via the counter-propagating backward beam. Starting from this
observation we generalise the ideas of attraction and rejection in nonlinear
multimode systems of arbitrary dimension, which paves the way towards a more
general idea of all-optical mode control. These ideas represent universal tools
to explore novel dynamics and applications in a variety of optical and
non-optical nonlinear systems. Coherent beam combination in
polarization-maintaining multicore fibres is demonstrated as example
Near to short wave infrared light generation through AlGaAs-on-insulator nanoantennas
AlGaAs-on-insulator (AlGaAs-OI) has recently emerged as a novel promising platform for nonlinear optics at the nanoscale. Among the most remarkable outcomes, second harmonic generation (SHG) in the visible/near infrared spectral region has been demonstrated in AlGaAs-OI nanoantennas (NA). In order to extend the nonlinear frequency generation towards the short wave infrared window, in this work we propose and demonstrate via numerical simulations difference frequency generation (DFG) in AlGaAs-OI NAs. The NA geometry is finely adjusted in order to obtain simultaneous optical resonances at the pump, signal and idler wavelengths, which results in an efficient DFG with conversion efficiencies up to 0.01%. Our investigation includes the study of the robustness against random variations of the NA geometry that may occur at fabrication stage. Overall, these outcomes identify a new potential and yet unexplored application of AlGaAs-OI NAs as compact devices for the generation and control of the radiation pattern in the near to short infrared spectral region
Nonlinear Polarization Manipulation in Optical Fibers
We describe the self-organization of light state-of-polarization in optical fiber based on a nonlinear cross-polarization interaction between an input signal and its backward replica. Several proof-of-principles for telecom applications are reported
All-optical regeneration of polarization of a 40-Gbit/s return-to-zero telecommunication signal
10We report all-optical regeneration of the state of polarization of a 40 Gbit∕s return-to-zero telecommunication signal.
The device discussed here consists of a 6.2-km-long nonzero dispersion-shifted fiber, with low polarization
mode dispersion, pumped from the output end by a backward propagating wave coming from either an external
continuous source or a reflection of the signal. An initially scrambled signal acquires a degree of polarization close
to 100% toward the polarization generator output. All-optical regeneration is confirmed by means of polarization
and bit-error-rate measurements as well as real-time observation of the eye diagrams. We show that the physical
mechanism underlying the observed four-wave-mixing-based polarization attraction phenomenon can be described
in terms of the geometric approach developed for the study of Hamiltonian singularities.openopenJ. Fatome; D. Sugny; S. Pitois; P. Morin; M. Guasoni; A. Picozzi; H. R. Jauslin; C. Finot; G. Millot; S. WabnitzJ., Fatome; D., Sugny; S., Pitois; P., Morin; Guasoni, Massimiliano; A., Picozzi; H. R., Jauslin; C., Finot; G., Millot; Wabnitz, Stefa
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