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Fabio Biancalana - One of the best experts on this subject based on the ideXlab platform.
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suppression and splitting of modulational instability sidebands in Periodically tapered optical fibers because of fourth order dispersion
Optics Letters, 2014Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We study the modulational instability induced by Periodic Variations of group-velocity dispersion in the proximity of the zero dispersion point. Multiple instability peaks originating from parametric resonance coexist with the conventional modulation instability because of fourth-order dispersion, which in turn is suppressed by the oscillations of dispersion. Moreover, isolated unstable regions appear in the space of parameters because of imperfect phase matching. This confirms the dramatic effect of Periodic tapering in the control and shaping of MI sidebands in optical fibers.
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vector modulational instability induced by parametric resonance in Periodically tapered highly birefringent optical fibers
Physical Review A, 2013Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We study the modulational instability induced by Periodic Variations of group-velocity dispersion and nonlinear coefficients in a highly birefringent fiber. We observe, for each resonance order, the presence of two pairs of genuine vector-type sidebands, which are spectrally unbalanced between the polarization components for nonzero group-index mismatch, and one pair of balanced sidebands emerging and dominating at increasing group-index mismatch. As the conventional modulational instability manifests itself, it is partially suppressed by the proximity of these additional unstable regions.
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tunable modulational instability sidebands via parametric resonance in Periodically tapered optical fibers
Optics Express, 2012Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We analyze the modulation instability induced by Periodic Variations of group velocity dispersion and nonlinearity in optical fibers, which may be interpreted as an analogue of the well-known parametric resonance in mechanics. We derive accurate analytical estimates of resonant detuning, maximum gain and instability margins, significantly improving on previous literature on the subject. We also design a Periodically tapered photonic crystal fiber, in order to achieve narrow instability sidebands at a detuning of 35 THz, above the Raman maximum gain peak of fused silica. The wide tunability of the resonant peaks by Variations of the tapering period and depth will allow to implement sources of correlated photon pairs which are far-detuned from the input pump wavelength, with important applications in quantum optics.
Mikko Tuomi - One of the best experts on this subject based on the ideXlab platform.
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signals embedded in the radial velocity noise Periodic Variations in the τ ceti velocities
Astronomy and Astrophysics, 2013Co-Authors: Mikko Tuomi, Robert A Wittenmyer, H R A Jones, J S Jenkins, C G Tinney, S S Vogt, J R Barnes, R P Butler, S J OtooleAbstract:Context. The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and 'jitter'. Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. Aims. We study an extensive set of radial velocities for the star HD 10700 (τ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. Methods. We performed Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reached our goal by adding artificial signals to the 'flat' radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilised various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals. Results. According to our analyses, moving average components with an exponential decay with a timescale from a few hours to few days, and Gaussian white noise explains the jitter the best for all three data sets. Fitting the corresponding noise parameters results in significant improvements of the statistical models and enables the detection of very weak signals with amplitudes below 1 m s-1 level in our numerical experiments. We detect significant Periodicities that have no activity-induced counterparts in the combined radial velocities. Three of these signals can be seen in the HARPS data alone, and a further two can be inferred by utilising the AAPS and Keck data. These Periodicities could be interpreted as corresponding to planets on dynamically stable close-circular orbits with periods of 13.9, 35.4, 94, 168, and 640 days and minimum masses of 2.0, 3.1, 3.6, 4.3, and 6.6 M⊕, respectively.
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signals embedded in the radial velocity noise Periodic Variations in the tau ceti velocities
arXiv: Earth and Planetary Astrophysics, 2012Co-Authors: Mikko Tuomi, Paul R Butler, Robert A Wittenmyer, H R A Jones, J S Jenkins, C G Tinney, S S Vogt, J R Barnes, S J Otoole, Jonathan HornerAbstract:The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and "jitter". Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. We study an extensive set of radial velocities for the star HD 10700 ($\tau$ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. We perform Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reach our goal by adding artificial signals to the "flat" radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilise various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals. ...
Andrea Armaroli - One of the best experts on this subject based on the ideXlab platform.
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suppression and splitting of modulational instability sidebands in Periodically tapered optical fibers because of fourth order dispersion
Optics Letters, 2014Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We study the modulational instability induced by Periodic Variations of group-velocity dispersion in the proximity of the zero dispersion point. Multiple instability peaks originating from parametric resonance coexist with the conventional modulation instability because of fourth-order dispersion, which in turn is suppressed by the oscillations of dispersion. Moreover, isolated unstable regions appear in the space of parameters because of imperfect phase matching. This confirms the dramatic effect of Periodic tapering in the control and shaping of MI sidebands in optical fibers.
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vector modulational instability induced by parametric resonance in Periodically tapered highly birefringent optical fibers
Physical Review A, 2013Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We study the modulational instability induced by Periodic Variations of group-velocity dispersion and nonlinear coefficients in a highly birefringent fiber. We observe, for each resonance order, the presence of two pairs of genuine vector-type sidebands, which are spectrally unbalanced between the polarization components for nonzero group-index mismatch, and one pair of balanced sidebands emerging and dominating at increasing group-index mismatch. As the conventional modulational instability manifests itself, it is partially suppressed by the proximity of these additional unstable regions.
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tunable modulational instability sidebands via parametric resonance in Periodically tapered optical fibers
Optics Express, 2012Co-Authors: Andrea Armaroli, Fabio BiancalanaAbstract:We analyze the modulation instability induced by Periodic Variations of group velocity dispersion and nonlinearity in optical fibers, which may be interpreted as an analogue of the well-known parametric resonance in mechanics. We derive accurate analytical estimates of resonant detuning, maximum gain and instability margins, significantly improving on previous literature on the subject. We also design a Periodically tapered photonic crystal fiber, in order to achieve narrow instability sidebands at a detuning of 35 THz, above the Raman maximum gain peak of fused silica. The wide tunability of the resonant peaks by Variations of the tapering period and depth will allow to implement sources of correlated photon pairs which are far-detuned from the input pump wavelength, with important applications in quantum optics.
S J Otoole - One of the best experts on this subject based on the ideXlab platform.
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signals embedded in the radial velocity noise Periodic Variations in the τ ceti velocities
Astronomy and Astrophysics, 2013Co-Authors: Mikko Tuomi, Robert A Wittenmyer, H R A Jones, J S Jenkins, C G Tinney, S S Vogt, J R Barnes, R P Butler, S J OtooleAbstract:Context. The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and 'jitter'. Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. Aims. We study an extensive set of radial velocities for the star HD 10700 (τ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. Methods. We performed Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reached our goal by adding artificial signals to the 'flat' radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilised various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals. Results. According to our analyses, moving average components with an exponential decay with a timescale from a few hours to few days, and Gaussian white noise explains the jitter the best for all three data sets. Fitting the corresponding noise parameters results in significant improvements of the statistical models and enables the detection of very weak signals with amplitudes below 1 m s-1 level in our numerical experiments. We detect significant Periodicities that have no activity-induced counterparts in the combined radial velocities. Three of these signals can be seen in the HARPS data alone, and a further two can be inferred by utilising the AAPS and Keck data. These Periodicities could be interpreted as corresponding to planets on dynamically stable close-circular orbits with periods of 13.9, 35.4, 94, 168, and 640 days and minimum masses of 2.0, 3.1, 3.6, 4.3, and 6.6 M⊕, respectively.
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signals embedded in the radial velocity noise Periodic Variations in the tau ceti velocities
arXiv: Earth and Planetary Astrophysics, 2012Co-Authors: Mikko Tuomi, Paul R Butler, Robert A Wittenmyer, H R A Jones, J S Jenkins, C G Tinney, S S Vogt, J R Barnes, S J Otoole, Jonathan HornerAbstract:The abilities of radial velocity exoplanet surveys to detect the lowest-mass extra-solar planets are currently limited by a combination of instrument precision, lack of data, and "jitter". Jitter is a general term for any unknown features in the noise, and reflects a lack of detailed knowledge of stellar physics (asteroseismology, starspots, magnetic cycles, granulation, and other stellar surface phenomena), as well as the possible underestimation of instrument noise. We study an extensive set of radial velocities for the star HD 10700 ($\tau$ Ceti) to determine the properties of the jitter arising from stellar surface inhomogeneities, activity, and telescope-instrument systems, and perform a comprehensive search for planetary signals in the radial velocities. We perform Bayesian comparisons of statistical models describing the radial velocity data to quantify the number of significant signals and the magnitude and properties of the excess noise in the data. We reach our goal by adding artificial signals to the "flat" radial velocity data of HD 10700 and by seeing which one of our statistical noise models receives the greatest posterior probabilities while still being able to extract the artificial signals correctly from the data. We utilise various noise components to assess properties of the noise in the data and analyse the HARPS, AAPS, and HIRES data for HD 10700 to quantify these properties and search for previously unknown low-amplitude Keplerian signals. ...
P Barrow - One of the best experts on this subject based on the ideXlab platform.
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search for event rate modulation in xenon100 electronic recoil data
Physical Review Letters, 2015Co-Authors: E Aprile, F Agostini, M Alfonsi, L Arazi, K Arisaka, F Arneodo, C Balan, J Aalbers, M Anthony, P BarrowAbstract:We have searched for Periodic Variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an un-binned profile likelihood analysis to identify any Periodicity up to 500 days. We find a global significance of less than 1 sigma for all periods suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8 sigma, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of WIMPs to electrons is excluded at 4.8 sigma.
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exclusion of leptophilic dark matter models using xenon100 electronic recoil data
Science, 2015Co-Authors: E Aprile, F Agostini, M Alfonsi, L Arazi, K Arisaka, F Arneodo, M Auger, C Balan, P Barrow, L BaudisAbstract:We have searched for Periodic Variations of the electronic recoil event rate in the (2-6) keV energy range recorded between February 2011 and March 2012 with the XENON100 detector, adding up to 224.6 live days in total. Following a detailed study to establish the stability of the detector and its background contributions during this run, we performed an un-binned profile likelihood analysis to identify any Periodicity up to 500 days. We find a global significance of less than 1 sigma for all periods suggesting no statistically significant modulation in the data. While the local significance for an annual modulation is 2.8 sigma, the analysis of a multiple-scatter control sample and the phase of the modulation disfavor a dark matter interpretation. The DAMA/LIBRA annual modulation interpreted as a dark matter signature with axial-vector coupling of WIMPs to electrons is excluded at 4.8 sigma.