129 research outputs found
Prediction of Performance Penalty due to Pump-Signal Overlap in Raman-amplified Systems
We present an efficient numerical model to predict the performance penalty induced by Rayleigh backscattered light arising from counter-propagating pumps in Ramanamplified ultra-wide-band transmission systems. The model is validated through comparison with experimental findings
Turismo cultural, patrimonio y eventos masivos : el Festival Nacional de Folclore de CosquĂn como recurso turĂstico.
Trabajo Final de PrĂĄctica ProfesionalEl presente trabajo analiza los antecedentes y la historia del desarrollo de la mĂșsica y la danza folclĂłrica como parte de la identidad del territorio argentino. Se intenta comprender la relaciĂłn entre la actividad turĂstica y la tradiciĂłn folclĂłrica explorando en los conceptos de patrimonio.Fil: Noverazco, Micaela Agustina. Universidad Nacional de San MartĂn. Escuela de EconomĂa y NegociosFil: Renaudier Spiazzi, RocĂo Macarena. Universidad Nacional de San MartĂn. Escuela de EconomĂa y Negocio
Numerical investigation of a feed-forward linewidth reduction scheme using a mode-locked laser model of reduced complexity
We provide numerical verification of a feed-forward, heterodyne-based phase noise reduction scheme using
single-sideband modulation that obviates the need for optical filtering at the output. The main benefit of a
feed-forward heterodyne linewidth reduction scheme is the simultaneous reduction of the linewidth of all modes
of a mode-locked laser (MLL) to that of a narrow-linewidth single-wavelength laser. At the heart of our simulator
is an MLL model of reduced complexity. Importantly, the main issue being treated is the jitter of MLLs and we
show how to create numerical waveforms that mimic the random-walk nature of timing jitter of pulses from
MLLs. Thus, the model does not need to solve stochastic differential equations that describe the MLL dynamics,
and the model calculates self-consistently the line-broadening of the modes of the MLL and shows good agreement with both the optical linewidth and jitter. The linewidth broadening of the MLL modes are calculated after
the phase noise reduction scheme and we confirm that the phase noise contribution from the timing jitter still
remains. Finally, we use the MLL model and phase noise reduction simulator within an optical communications
system simulator and show that the phase noise reduction technique could enable MLLs as optical carriers for
higher-order modulation formats, such as 16-state and 64-state quadrature amplitude modulation
Automated Estimation of the Spinal Curvature via Spine Centerline Extraction with Ensembles of Cascaded Neural Networks
Scoliosis is a condition defined by an abnormal spinal curvature. For
diagnosis and treatment planning of scoliosis, spinal curvature can be
estimated using Cobb angles. We propose an automated method for the estimation
of Cobb angles from X-ray scans. First, the centerline of the spine was
segmented using a cascade of two convolutional neural networks. After smoothing
the centerline, Cobb angles were automatically estimated using the derivative
of the centerline. We evaluated the results using the mean absolute error and
the average symmetric mean absolute percentage error between the manual
assessment by experts and the automated predictions. For optimization, we used
609 X-ray scans from the London Health Sciences Center, and for evaluation, we
participated in the international challenge "Accurate Automated Spinal
Curvature Estimation, MICCAI 2019" (100 scans). On the challenge's test set, we
obtained an average symmetric mean absolute percentage error of 22.96
PDM-QPSK: on the system benefits arising from temporally interleaving polarization tributaries at 100Gb/s.
We experimentally study, over a dispersion-managed link relying on low chromatic dispersion fibre, the origins of the system benefits provided by temporally interleaving the polarization tributaries of 100Gb/s coherent RZ-PDM-QPSK by half a symbol period. Hence, we demonstrate that the amount of benefits provided by this technique is dependent on the configuration of the WDM transmission system
Devices and Fibers for Ultrawideband Optical Communications
Wavelength-division multiplexing (WDM) has
historically enabled the increase in the capacity of optical
systems by progressively populating the existing optical bandwidth
of erbium-doped fiber amplifiers (EDFAs) in the C-band.
Nowadays, the number of channelsâneeded in optical
systemsâis approaching the maximum capacity of standard
C-band EDFAs. As a result, the industry worked on novel
approaches, such as the use of multicore fibers, the extension
of the available spectrum of the C-band EDFAs, and the
development of transmission systems covering C- and L-bands
and beyond. In the context of continuous traffic growth,
ultrawideband (UWB) WDM transmission systems appear
as a promising technology to leverage the bandwidth of
already deployed optical fiber infrastructure and sustain the
traffic demand for the years to come. Since the pioneering
demonstrations of UWB transmission a few years ago, long
strides have been taken toward UWB technologies. In this
review article, we discuss how the most recent advances in
the design and fabrication of enabling devices, such as lasers,
amplifiers, optical switches, and modulators, have improved
the performance of UWB systems, paving the way to turn
research demonstrations into future products. In addition,
we also report on the advances in UWB optical fibers, such as
the recently introduced nested antiresonant nodeless fibers
(NANFs), whose future implementations could potentially provide
up to 300-nm-wide bandwidth at less than 0.2 dB/km loss
Self-generation of optical frequency comb in single section Quantum Dot Fabry-Perot lasers: a theoretical study
Optical Frequency Comb (OFC) generated by semiconductor lasers are currently
widely used in the extremely timely field of high capacity optical
interconnects and high precision spectroscopy. Very recently, several
experimental evidences of spontaneous OFC generation have been reported in
single section Quantum Dot (QD) lasers. Here we provide a physical
understanding of these self-organization phenomena by simulating the multi-mode
dynamics of a single section Fabry-Perot (FP) QD laser using a Time-Domain
Traveling-Wave (TDTW) model that properly accounts for coherent
radiation-matter interaction in the semiconductor active medium and includes
the carrier grating generated by the optical standing wave pattern in the laser
cavity. We show that the latter is the fundamental physical effect at the
origin of the multi-mode spectrum appearing just above threshold. A
self-mode-locking regime associated with the emission of OFC is achieved for
higher bias currents and ascribed to nonlinear phase sensitive effects as Four
Wave Mixing (FWM). Our results are in very good agreement with the experimental
ones
Low transmission penalty dual-stage broadband discrete Raman amplifier
We present a broadband (>70nm), dual stage, discrete Raman amplifier designed with small and standard core fibres to maximize gain and minimize nonlinearity. The amplifier provides ~19.5dB net gain, 22.5dBm saturation output power and a noise figure of <7.2dB. 120Gb/s DP-QPSK transmission over 38x80km at a pre-FEC BER <3.8x10â3 is demonstrated
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