Search results for " Modulation"

ultra-short pulse propagation at 160-Gb/s in dispersion managed optical fiber lines

2004

This thesis presents a study on ultra-short pulse propagation at 160-Gb/s in dispersion managed optical fiber lines. In a first part, we describe the experimental design of a SHG-FROG setup able to characterize high repetition rate pulse trains. Secondly, we demonstrate the efficiency of multiple four wave mixing phenomenon for the generation of a 160-GHz pulse train through the compression of a sinusoidal beat-signal. Then, in order to compare the experimental and theoretical results, we present the development of an optical fiber characterization benchtop based on modulational instability. In the last part of this thesis, we built and compare several recirculating loop setups. On the one …

Potentialities of glass air-clad micro- and nanofibers for nonlinear optics

2010

Micro- and nanofibers constitute an attractive platform for testing nonlinear devices with millimeter size in a simple and flexible fashion, with potential applications in ultra-fast all-optical communications. In this article, we present challenges that must be addressed and targets that can be reached using such a platform. We describe a tunable laser source capable of delivering pulses with a kilowatt peak power and a sub-0.1-nm linewidth that is specially designed for the study of resonant devices such as the nonlinear loop resonator. Experimental and simulation results are presented for silica microfiber based nonlinear devices. The prospect of developing hybrid devices combining highl…

Analysis of multiple internal reflections in a parallel aligned liquid crystal on silicon SLM

2014

Multiple internal reflection effects on the optical modulation of a commercial reflective parallel-aligned liquid-crystal on silicon (PAL-LCoS) spatial light modulator (SLM) are analyzed. The display is illuminated with different wavelengths and different angles of incidence. Non-negligible Fabry-Perot (FP) effect is observed due to the sandwiched LC layer structure. A simplified physical model that quantitatively accounts for the observed phenomena is proposed. It is shown how the expected pure phase modulation response is substantially modified in the following aspects: 1) a coupled amplitude modulation, 2) a non-linear behavior of the phase modulation, 3) some amount of unmodulated light…

Simultaneous remote extraction of multiple speech sources and heart beats from secondary speckles pattern

2009

The ability of dynamic extraction of remote sounds is very appealing. In this manuscript we propose an optical approach allowing the extraction and the separation of remote sound sources. The approach is very modular and it does not apply any constraints regarding the relative position of the sound sources and the detection device. The optical setup doing the detection is very simple and versatile. The principle is to observe the movement of the secondary speckle patterns that are generated on top of the target when it is illuminated by a spot of laser beam. Proper adaption of the imaging optics allows following the temporal trajectories of those speckles and extracting the sound signals ou…

Efficient Simulation of Orthogonal Multicarrier Transmission over Multipath Fading Channels

2011

Filterbank orthogonal multicarrier transmission schemes, such as OFDM/OQAM, are currently under intense study for their spectral efficiency and suitability for the physical layer of Cognitive Radio. Nonetheless, the mathematical description of the signal is cumbersome, and closed form expressions for performance figures are not available, so performance analysis on fading channels has to be performed by means of simulations. We propose an algorithm for simulating the received signal over multipath frequency selective fading channels, based on Taylor series expansion of the channel transfer function. The proposed method is compared to the state-of-the-art FFT-based method in terms of computa…

A 16QAM super-orthogonal space-frequency code for broadband mobile communication systems with two transmit antennas

2010

We combine our previously designed 32-state super-orthogonal space-time trellis code (SOSTTC) with orthogonal frequency division multiplexing (OFDM) to build a broadband mobile communication system having a spectral efficiency that amounts to 4 bits/s/Hz depending on the length of the cyclic prefix used to avoid interframe interference. The transmitter is equipped with two antennas, where the OFDM frames they transmit are not independent, as they carry the same information in an orthogonal form. The 2N OFDM tones are grouped in N pairs of tones. Each group of two tones transmits the entries of a 2×2 orthogonal matrix. In our case, the entries are symbols taken from the rectangular 16-point …

Combining transcranial magnetic stimulation and subdural electrodes for pain modulation

2017

COX-2 inhibition and pain management: a review summary

2005

Cyclooxygenase-2 selective inhibitors have long been regarded as potent anti-inflammatory drugs for the treatment of arthritis, osteoarthritis and dysmenorrhea. The reports of cardiovascular risk and the subsequent withdrawal of rofecoxib, and recently valdecoxib, has called the therapeutic potential of coxibs into question. Currently, according to the latest decisions of the US Food and Drug Administration and European Medicines Agency, the approval of valdecoxib has been refused for 1 year due to an increased rate of cardiovascular risks and serious skin reactions. There are restrictions concerning the use of all other coxibs. The short-time use of coxibs, however, in anti-inflammatory tr…

Decision letter: Differential dopaminergic modulation of spontaneous cortico–subthalamic activity in Parkinson’s disease

2021

Isolation and Characterization of CD276+/HLA-E+ Human Subendocardial Mesenchymal Stem Cells from Chronic Heart Failure Patients: Analysis of Differen…

2012

Mesenchymal stem cells (MSCs) are virtually present in all postnatal organs as well as in perinatal tissues. MSCs can be differentiated toward several mature cytotypes and interestingly hold potentially relevant immunomodulatory features. Myocardial infarction results in severe tissue damage, cardiomyocyte loss, and eventually heart failure. Cellular cardiomyoplasty represents a promising approach for myocardial repair. Clinical trials using MSCs are underway for a number of heart diseases, even if their outcomes are hampered by low long-term improvements and the possible presence of complications related to cellular therapy administration. Therefore, elucidating the presence and role of MS…