The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform

Silvia M. Pietralunga - One of the best experts on this subject based on the ideXlab platform.

  • Local Birefringence In Optical Fibers for Low-PMD Performances
    2007 9th International Conference on Transparent Optical Networks, 2007
    Co-Authors: Maddalena Ferrario, Silvia M. Pietralunga
    Abstract:

    The introduction of a Spinning step in the drawing process is a primary way to improve optical fiber performances in terms of Polarization Mode Dispersion (PMD), by modifying fiber intrinsic birefringence. However, Spin profiles actually transferred into fibers may differ from nominally imparted ones, leading to departures from the expected efficiency in PMD reduction. Therefore, for best optimization of low-PMD fibers, it is useful to investigate the effect of Spinning, in terms of effectiveness of Spin Function transfer and modification of local intrinsic birefringence. In this review, after a brief theoretical excursion over different types of Spin Functions and related effects on PMD, we introduce measurement methods featuring high spatial resolution and enabling the reconstruction of local birefringence evolution along spun fibers. In this way, the overall effect of Spinning on birefringence and related PMD can be experimentally verified, as will be summarized.

  • Local Birefringence in Unidirectionally Spun Fibers
    Journal of Lightwave Technology, 2006
    Co-Authors: Silvia M. Pietralunga, Maddalena Ferrario, Matteo Tacca, Mario Martinelli
    Abstract:

    The application of a Spinning step in the drawing process is known to improve optical-fiber polarization mode dispersion. For a more comprehensive understanding of the mechanism through which Spinning modifies fiber performances, in this paper, the authors investigate the effect of unidirectional Spinning on local fiber birefringence in terms of the effectiveness of Spin-Function transfer and reduction of the local intrinsic birefringence under different drawing conditions. The actual frozen-in Spin is experimentally recovered by means of a cut-back procedure. Different from the case of a periodic Spinning, a unidirectional Spinning correctly reproduces the nominally imparted Spin rate in agreement with theoretical modelizations of the transfer effectiveness of the Spinning process. A theoretical explanation for the experimental evidence, recently proved by tomographic stress measurements, of Spinning affecting fiber linear intrinsic birefringence is provided. In particular, the interaction of drawing parameters and Spinning process in defining stress development into fibers is considered. To validate the proposed model, further tomographic reconstructions of stress profiles in fiber spun at different rates and drawing speed were carried out. Besides, corresponding stress-induced birefringence values were estimated and compared with those recovered by the cut-back technique. Variations of spun fiber beatlength values with respect to the unspun case, as obtained from both measurement techniques, are in good agreement, providing a further reliable confirmation that an improvement of the beatlength may proceed as a consequence of the applied Spin

Andreas Bette - One of the best experts on this subject based on the ideXlab platform.

  • Twistor Phase Space Dynamics and the Lorentz Force Equation
    arXiv: High Energy Physics - Theory, 1995
    Co-Authors: Andreas Bette
    Abstract:

    Using Lorentz force equation as an input a Hamiltonian mechanics on the non-projective two twistor phase space TxT is formulated. Such a construction automatically reproduces dynamics of the intrinsic classical relativistic Spin. The charge appears as a dynamical variable. It is also shown that if the classical relativistic Spin Function on TxT vanishes, the natural conformally invariant symplectic structure on TxT reduces to the natural symplectic structure on the cotangent bundle of the Kaluza-Klein space.

  • Twistor phase space dynamics and the Lorentz force equation
    Journal of Mathematical Physics, 1993
    Co-Authors: Andreas Bette
    Abstract:

    Using the Lorentz force equation as an input a Hamiltonian mechanics on the nonprojective two twistor phase space T×T is formulated. Such a construction automatically reproduces dynamics of the intrinsic classical relativistic Spin. The charge appears as a dynamical variable. It is also shown that if the classical relativistic Spin Function on T×T vanishes, the natural conformally invariant symplectic structure on T×T reduces to the natural symplectic structure on the cotangent bundle of the Kal/uza–Klein space.

A. Pizzinat - One of the best experts on this subject based on the ideXlab platform.

  • Calculation of the mean differential group delay of periodically spun, randomly birefringent fibers.
    Optics Letters, 2002
    Co-Authors: Andrea Galtarossa, Paola Griggio, A. Pizzinat, Luca Palmieri
    Abstract:

    Spinning is one of the most effective and well-known ways to reduce polarization mode dispersion of optical fibers. In spite of the popularity of Spinning, a detailed theory of Spin effects is still lacking. We report an analytical expression for the mean differential group delay of a randomly birefringent spun fiber. The result holds for any periodic Spin Function with a period shorter than the fiber’s beat length.

  • Optimized Spinning design for low PMD fibers: an analytical approach
    Journal of Lightwave Technology, 2001
    Co-Authors: A. Galtarossa, L. Palmieri, A. Pizzinat
    Abstract:

    It is known that the differential group delay (DGD) due to polarization mode dispersion (PMD) can be effectively reduced by Spinning the fiber during drawing. In this paper, we propose an analytical approach that allows optimization of the Spinning design. The fundamental idea is that, in the absence of polarization coupling, an optimized Spinning profile can balance the effects of the intrinsic linear birefringence so that the differential group delay can be forced to be periodic and, consequently, have a limited amplitude as a Function of distance. Our approach Is independent of the Spin profile. In other words, with a fixed set of parameters that characterize a particular Spin Function, we are able to find analytically the values corresponding to a periodic DGD in a deterministic regime. Numerical results based on waveplate model confirm the analytical prediction and show that PMD can be reduced by about two orders of magnitude with respect to the same fiber without Spinning, even after the introduction of random polarization coupling.

Maddalena Ferrario - One of the best experts on this subject based on the ideXlab platform.

  • Local Birefringence In Optical Fibers for Low-PMD Performances
    2007 9th International Conference on Transparent Optical Networks, 2007
    Co-Authors: Maddalena Ferrario, Silvia M. Pietralunga
    Abstract:

    The introduction of a Spinning step in the drawing process is a primary way to improve optical fiber performances in terms of Polarization Mode Dispersion (PMD), by modifying fiber intrinsic birefringence. However, Spin profiles actually transferred into fibers may differ from nominally imparted ones, leading to departures from the expected efficiency in PMD reduction. Therefore, for best optimization of low-PMD fibers, it is useful to investigate the effect of Spinning, in terms of effectiveness of Spin Function transfer and modification of local intrinsic birefringence. In this review, after a brief theoretical excursion over different types of Spin Functions and related effects on PMD, we introduce measurement methods featuring high spatial resolution and enabling the reconstruction of local birefringence evolution along spun fibers. In this way, the overall effect of Spinning on birefringence and related PMD can be experimentally verified, as will be summarized.

  • Local Birefringence in Unidirectionally Spun Fibers
    Journal of Lightwave Technology, 2006
    Co-Authors: Silvia M. Pietralunga, Maddalena Ferrario, Matteo Tacca, Mario Martinelli
    Abstract:

    The application of a Spinning step in the drawing process is known to improve optical-fiber polarization mode dispersion. For a more comprehensive understanding of the mechanism through which Spinning modifies fiber performances, in this paper, the authors investigate the effect of unidirectional Spinning on local fiber birefringence in terms of the effectiveness of Spin-Function transfer and reduction of the local intrinsic birefringence under different drawing conditions. The actual frozen-in Spin is experimentally recovered by means of a cut-back procedure. Different from the case of a periodic Spinning, a unidirectional Spinning correctly reproduces the nominally imparted Spin rate in agreement with theoretical modelizations of the transfer effectiveness of the Spinning process. A theoretical explanation for the experimental evidence, recently proved by tomographic stress measurements, of Spinning affecting fiber linear intrinsic birefringence is provided. In particular, the interaction of drawing parameters and Spinning process in defining stress development into fibers is considered. To validate the proposed model, further tomographic reconstructions of stress profiles in fiber spun at different rates and drawing speed were carried out. Besides, corresponding stress-induced birefringence values were estimated and compared with those recovered by the cut-back technique. Variations of spun fiber beatlength values with respect to the unspun case, as obtained from both measurement techniques, are in good agreement, providing a further reliable confirmation that an improvement of the beatlength may proceed as a consequence of the applied Spin

Aaron Pollack - One of the best experts on this subject based on the ideXlab platform.

  • The Spin -Function on for Siegel modular forms
    Compositio Mathematica, 2017
    Co-Authors: Aaron Pollack
    Abstract:

    We give a Rankin-Selberg integral representation for the Spin (degree eight) $L$-Function on $\mathrm{PGSp}_6$. The integral applies to the cuspidal automorphic representations associated to Siegel modular forms. If $\pi$ corresponds to a level one Siegel modular form $f$ of even weight, and if $f$ has a non-vanishing maximal Fourier coefficient (defined below), then we deduce the Functional equation and finiteness of poles of the completed Spin $L$-Function $\Lambda(\pi,Spin,s)$ of $\pi$.

  • The Spin -Function on for Siegel modular forms
    Compositio Mathematica, 2017
    Co-Authors: Aaron Pollack
    Abstract:

    We give a Rankin–Selberg integral representation for the Spin (degree eight) $L$-Function on $\operatorname{PGSp}_{6}$ that applies to the cuspidal automorphic representations associated to Siegel modular forms. If $\unicode[STIX]{x1D70B}$ corresponds to a level-one Siegel modular form $f$ of even weight, and if $f$ has a nonvanishing maximal Fourier coefficient (defined below), then we deduce the Functional equation and finiteness of poles of the completed Spin $L$-Function $\unicode[STIX]{x1D6EC}(\unicode[STIX]{x1D70B},\text{Spin},s)$ of $\unicode[STIX]{x1D70B}$.