Showing papers by "Daniel J. Gauthier published in 2008"

Optimal pump profile designs for broadband SBS slow-light systems

Abstract: We describe a methodology for designing the optimal gain profiles for gain-based, tunable, broadband, slow-light pulse delay devices based on stimulated Brillouin scattering. Optimal gain profiles are obtained under system constraints such as distortion, total pump power, and maximum gain. The delay performance of three candidate systems: Gaussian noise pump broadened (GNPB), optimal gain-only, and optimal gain+absorption are studied using Gaussian and super-Gaussian pulses. For the same pulse bandwidth, we find that the optimal gain+absorption medium improves the delay performance by 2.1 times the GNPB medium delay and 1.3 times the optimal gain-only medium delay for Gaussian pulses. For the super-Gaussian pulses the optimal gain-only medium provides a fractional pulse delay 1.8 times the GNPB medium delay.

Fiber-Based Slow-Light Technologies

Abstract: A review of current fiber-based technologies capable of producing slow-light effects is presented, with emphasis on the applicability of these technologies to telecommunications. We begin with a review of the basic concepts of phase velocity, group velocity, and group delay. We then present a survey of some of the figures of merit used to quantify the engineering properties of slow-light systems. We also present a description of several of the physical processes that are commonly used to induce a slow-light effect. Finally, a review of some recent advances in this field is presented.

Complementary methods to assist subcellular fractionation in organellar proteomics.

Abstract: Organellar proteomics aims to describe the full complement of proteins of subcellular structures and organelles. When compared with whole-cell or whole-tissue proteomes, the more focused results from subcellular proteomic studies have yielded relatively simpler datasets from which biologically relevant information can be more easily extracted. In every proteomic study, the quality and purity of the biological sample to be investigated is of the utmost importance for a successful analysis. In organellar proteomics, one of the most crucial steps in sample preparation is the initial subcellular fractionation procedure by which the enriched preparation of the sought-after organelle is obtained. In nearly all available organellar proteomic studies, the method of choice relies on one or several rounds of density-based gradient centrifugation. Although this method has been recognized for decades as yielding relatively pure preparations of organelles, recent technological advances in protein separation and identi...

Flow cytometry-assisted purification and proteomic analysis of the corticotropes dense-core secretory granules

Abstract: The field of organellar proteomics has emerged as an attempt to minimize the complexity of the proteomics data obtained from whole cell and tissue extracts while maximizing the resolution on the protein composition of a single subcellular compartment. Standard methods involve lengthy density-based gradient and/or immunoaffinity purification steps followed by extraction, 1-DE or 2-DE, gel staining, in-gel tryptic digestion, and protein identification by MS. In this paper, we present an alternate approach to purify subcellular organelles containing a fluorescent reporter molecule. The gel-free procedure involves fluorescence-assisted sorting of the secretory granules followed by gentle extraction in a buffer compatible with tryptic digestion and MS. Once the subcellular organelle labeled, this procedure can be done in a single day, requires no major modification to any instrumentation and can be readily adapted to the study of other organelles. When applied to corticotrope secretory granules, it led to a much enriched granular fraction from which numerous proteins could be identified through MS.

Observation of large 10-Gb/s SBS slow light delay with low distortion using an optimized gain profile.

Abstract: An optimum SBS gain profile is designed to achieve better slow-light performance. It consists of a nearly flat-top profile with sharp edges. Tunable delays up to 3 pulse widths for 100-ps-long input pulses, corresponding to 10 Gb/s data rates, are found while keeping an output-input pulse-width ratio below 1.8. Bit-error-rate (BER) measurements performed for a non-return-to-zero modulation format demonstrates 28 ps of delay under error-free operation.

Transverse patterns for all-optical switching

Abstract: Transverse optical patterns, generated by nonlinear interactions, rotate in the presence of a weak switch beam. Using an experimental system with increased symmetry, we observe that the switch can be actuated by ~2100 photons.

Kinetic study and characterization of sewage sludge for its incineration

Abstract: The sewage sludge from San Juan, Argentina, was characterized in an attempt to improve the thermal treatment efficiency and to reduce the environmental impact of incineration. The ash content is about 50% dry basis, and its weight loss at 105 °C was high. Taking into account the moisture content, it required drying for an autothermal combustion, thus imposing an additional combustible for incineration. The sludge contains high concentrations of several trace elements, and all but Hg are two to fivefold more concentrated in its ash. Thermogravimetric analyses were carried out on dry samples of sludge in inert and oxidative atmosphere. Three peaks can be observed in all differential thermogravimetric curves during the organic matter decomposition. The pyrolysis curve is over the combustion curve and parallel to it up to high temperatures. A kinetic model of the sludge weight loss during its incineration, based on these studies and combining the multi-step pyrolysis and combustion processes, is proposed and ...

High-Resolution High-Speed Panoramic Cardiac Imaging System

Abstract: A panoramic cardiac imaging system consisting of three high-speed CCD cameras has been developed to image the surface electrophysiology of a rabbit heart via fluorescence imaging using a voltage-sensitive fluorescent dye. A robust, unique mechanical system was designed to accommodate the three cameras and to adapt to the requirements of future experiments. A unified computer interface was created for this application-a single workstation controls all three CCD cameras, illumination, stimulation, and a stepping motor that rotates the heart. The geometric reconstruction algorithms were adapted from a previous cardiac imaging system. We demonstrate the system by imaging a polymorphic cardiac tachycardia.

Apparatus and Methods Using Highly Optically Dispersive Media

Abstract: Embodiments of the invention pertain to the optical phenomena of ‘slow-light’ and ‘fast-light’, provided by a highly optically dispersive medium; that is, one in which the absolute value of the group index of refraction of the medium is equal to or greater than four Apparatus embodiments of the invention are directed to an optical spectroscopic parameter detection and/or measurement apparatus In various non-limiting aspects, the apparatus may be in the form of an interferometer, a spectral interferometer, a spectrometer, a wavemeter, a tunable narrowband filter, and other such devices Various non-limiting, exemplary apparatus may include a two-beam interferometer, a multiple-beam interferometer, a grating-based interferometer/spectrometer, a Fourier-Transform interferometer, and others The embodied devices include a highly dispersive medium that appropriately can facilitate either a slow-light effect or a fast-light effect, which is disposed in a propagation path of an electromagnetic (EM) input field and, a detector disposed in a manner to detect an output field resulting from the input filed interaction with the highly dispersive medium Method embodiments involve measuring a spectroscopic parameter with significantly enhanced bandwidth and/or sensitivity and/or resolving power and/or accuracy over currently available measurement techniques, using an embodied optical spectroscopic parameter detection and/or measurement apparatus that incorporates a highly dispersive medium

Room-temperature spectral hole burning in an engineered inhomogeneously broadened resonance.

Abstract: We observe spectral hole burning in a room-temperature optical fiber pumped by a spectrally broadened pump beam. This beam drives the stimulated Brillouin process, creating an inhomogeneously broadened resonance in the material whose shape can be engineered by tailoring the beam's spectrum. A monochromatic saturating beam “burns” a narrow spectral hole that is ~104 times narrower than the inhomogeneous width of the resonance. This research paves the way toward agile optical information processing and storage using standard telecommunication components.

Controlling Fast Chaos in Optoelectronic Delay Dynamical Systems

Abstract: 1.1 Introduction Recent studies have shown that fast chaotic dynamics can be used for a variety of applications such as information transmission with high power efficiency [1], generating truly random numbers [2,3], radar [4–8], as well as novel spread spectrum [9], ultrawide-bandwidth [10, 11], and optical [12, 13] communication schemes. In these applications, it is desirable to generate chaos in the fast regime where the typical time scale of the fluctuations is on the order of 1 ns or less [12, 14]. The ability to control the chaotic trajectory to specific regions in phase space is also desirable [1, 15, 16]. For applications requiring controlled trajectories, it is possible to use recently developed chaos-control methods. The key idea underlying these techniques is to stabilize a desired dynamical behavior by applying feedback through minute perturbations to an accessible parameter when the system is in a neighborhood of the desired trajectory in state-space [17–19]. In particular, many of the control protocols attempt to stabilize one of the unstable periodic orbits (UPOs) that are embedded in the chaotic attractor (although the control of unstable steady state has also been investigated, see, for example, Refs. [20–23]). Whereas the control of UPOs has been very successful for slow systems (characteristic time scale > 1 µs) [24–27], applying feedback control to fast chaotic systems is challenging because the controller requires a finite time to sense the current state of the system, determine the appropriate perturbation, and apply it to the system. This finite time interval, often called the control-loop latency τ , can be problematic if the state of the system is no longer correlated with its measured state at the time when the perturbation is applied. Typically, chaos control fails when the latency is on the order of the period of the UPO to be stabilized [28–30]. Another difficulty faced in controlling fast chaos is the fact that many high-speed chaos generators are delay dynamical systems. Time-delayed feedback occurs naturally in high-speed systems, where the time it takes signals to propagate through the device components is comparable to the time scale of

Observation of Large 8-Gb/s SBS Slow Light Delay with Low Distortion Using an Optimized Gain Profile

Abstract: We obtain over 3 pulse widths SBS slow light delay for an input pulse width of 125 ps. By optimizing the gain profile, the output-to-input pulse width ratio is less than 2.

Slow light and stored light using SBS in an optical fiber

Abstract: Recently, slow light and stored light has been achieved in room temperature optical fibers at telecommunication wavelengths, which is accelerating the transition of these techniques to applications. This presentation will review the physics behind these fascinating effects and describe recent progress.

Effects of Brillouin slow light on intensity- modulated waveforms in optical fibers

Abstract: We demonstrate a theoretical analysis and the experimental confirmation of the effects of Brillouin slow light on intensity-modulated waveforms in optical fibers. The results show that the DC and the AC parts of the waveform experience different Brillouin gain according to the modulation frequency, and the time delay of the intensity-modulated signal can be used to directly measure the phase-index change of the slow light configuration.

Room-Temperature Spectral Hole Burning via SBS

Abstract: We observe spectral hole burning in a room-temperature optical fiber due to saturation of the stimulated Brillouin scattering process. The spectral hole is ~10,000 times narrower than the width of the resonance.