A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation, photonic crystal fiber

Ghrelin degradation by serum and tissue homogenates: identification of the cleavage sites

Subsequent to the discovery of ghrelin as the endogenous ligand of growth hormone secretagogue receptor 1a, this unique gut peptide has been found to exert numerous physiological effects, such as appetite stimulation and lipid accumulation via the central regulating mechanisms in the hypothalamus, stimulation of gastric motility, regulation of glucose metabolism and brown fat thermogenesis, and modulation of stress, anxiety, taste sensation, reward-seeking behaviour and the sleep/wake cycle. Prader-Willi syndrome (PWS) has been described as a unique pathological state characterised by severe obesity and high circulating levels of ghrelin. It was hypothesised that hyperghrelinaemia would explain at least a part of the feeding behaviour and body composition of PWS patients, who are characterised by hyperphagia, an obsession with food and food-seeking, and increased adiposity. Initially, the link between hyperghrelinaemia and growth hormone deficiency, which is observed in 90% of the children with PWS, was not fully understood. Over the years, however, the increasing knowledge on ghrelin, PWS features and the natural history of the disease has led to a more comprehensive description of the abnormal ghrelin system and its role in the pathophysiology of this rare and complex neurodevelopmental genetic disease. In the present study, we (a) present the current view of PWS; (b) explain its natural history, including recent data on the ghrelin system in PWS patients; and (c) discuss the therapeutic approach of modulating the ghrelin system in these patients and the first promising results.

Prader-Willi syndrome: A model for understanding the ghrelin system.

Validated determination of losartan and valsartan in human plasma by stir bar sorptive extraction based on acrylate monolithic polymer, liquid chromatographic analysis and experimental design methodology.

The physics and applications of fiber-based supercontinuum (SC) sources have been a subject of intense interest over the last decade, with significant impact on both basic science and industry. New uses for SC sources are also constantly emerging due to their unique properties that combine high brightness, multi-octave frequency bandwidth, fiber delivery, and single-mode output. The last few years have seen significant research efforts focused on extending the wavelength coverage of SC sources towards the 2 to 20µm molecular fingerprint mid-infrared (MIR) region and in the ultraviolet (UV) down to 100 nm, while also improving stability, noise and coherence, output power, and polarization properties. Here we review a selection of recent advances in SC generation in a range of specialty optical fibers, including fluoride, chalcogenide, telluride, and silicon-core fibers for the MIR; UV-grade silica fibers and gas-filled hollow-core fibers for the UV range; and all-normal dispersion fibers for ultralow-noise coherent SC generation.

Recent advances in supercontinuum generation in specialty optical fibers [Invited]

Carcinogenic and non-carcinogenic risk assessment induced by pesticide residues in honey of Iran based on Monte Carlo Simulation

We report the generation of a low noise, octave-spanning supercontinuum in the normal dispersion regime of a multimode chalcogenide fiber with 100 μm core size. The noise performances are characterized in different output wavelength bands.

Low-Noise Octave Spanning Mid-Infrared Supercontinuum Generation in a Large Core Chalcogenide Fiber

Supercontinuum light (SC) is a broadband source with unique properties as the result of cascaded nonlinear dynamics when intense light propagates in a nonlinear material [1]. Recently, the generation of broadband SC sources operating in the mid-infrared (MIR) has attracted significant interest due to a wide range of potential applications in spectroscopy [2], microscopy, molecular fingerprinting [3], environmental monitoring and LIDAR [4], just to name a few. Fibers made of non-silica soft glasses such as fluoride, tellurite and chalcogenide are good candidates for SC generation in the MIR due to their high intrinsic nonlinearity and wide transparency window in this wavelength range. Supercontinuum generation in the MIR is typically achieved by propagating femtosecond pulses into the anomalous dispersion regime of a single-mode soft glass fibers. This typically leads to SC sources which are limited in terms of average power due to the low damage threshold associated with soft glasses and susceptible to noise due to the anomalous pump regime. These inherent limitations can be detrimental for many applications such as e.g. optical coherence tomography (OCT), photoacoustic imaging [5], or spectroscopy where the performance critically depends on the power and noise properties of the light source. In this work, we demonstrate for the first time the generation of a low noise high power SC in the MIR by injecting 350 fs pulses from an optical parametric amplifier into the normal dispersion regime of a one meter-long multimode step-index chalcogenide fiber with 100 µm core diameter. We show the generation of SC spanning from 1700 nm to 4800 nm for a pump wavelength at 3500 nm (located in normal dispersion regime of the used fiber) and an input peak power of 570 kW. A systematic study of the SC intensity noise is performed as a function of different pump parameters and for different output wavelengths show that the initial fluctuations on the pump laser are at most amplified by a factor of 2 at the spectral edge of the SC. Although the output beam in this case is multimoded, it can still be used for many practical applications such as long-distance remote sensing for which high power and low noise are more essential than the actual beam profile quality. Our results open novel perspective for the generation of high power low-noise broadband light sources in the MIR.

Low noise mid-infrared supercontinuum generation in multimode chalcogenide fiber (Conference Presentation)

The generation of a broadband supercontinuum (SC) in the mid-infrared has attracted significant attention in the past few years due the wide range of possible applications in e.g. microscopy, medical diagnostics, gas sensing and imaging [1] as many molecules exhibit strong vibrational absorption bands in this wavelength range. Fibers based on fluoride, tellurite, or chalcogenide soft glasses are typically used for SC generation in the mid-infrared due to their broad transmission window and high nonlinear refractive index. These glasses, however, inherently suffer from a low damage threshold and their synthesis and processing can be challenging. In order to overcome the power limitation and scale up the SC output power, multimode fibers have attracted growing interest with SC generation demonstrations in step index multimode fluoride and chalcogenide fibers [2] . While attractive, these SC sources are nevertheless highly multimoded making them undesirable for several applications. Silicate glasses with high concentration of the heavy metal oxides on the other hand offer a good trade off between easy synthesis, broad transmission window and relatively high nonlinearity. They are also thermally stable and their composition may be tuned by changing the dopants concentration allowing to engineer their characteristics. Among those, leadbismuth-gallium silicate glasses (PBG) have shown to be promissing material for fiber fabrication with comparable nonlinearity to that of tellurite glasses and transmission up to 5.5 micron [3] . Here, we demonstrate for the first time the generation of octave-spanning supercontinuum in PBG graded-index multimode fiber using femtosecond pulses ( Fig 1 ).

Octave-spanning Infrared Supercontinuum Generation in a Graded-Index Multimode Lead-Bismuth-Gallate Fiber

Supercontinuum light (SC) is a broadband source with unique properties generated via cascaded nonlinear processes when intense light propagates in a nonlinear material [1]. Depending on the nonlinear material and pump source used, the spectrum of a SC source can span from the visible to the mid-infrared with up to several Watt-average power. Recently, the generation of broadband SC sources operating in the mid-infrared (MIR) has attracted significant interest due to a wide range of potential applications in spectroscopy [2], microscopy [3], molecular fingerprinting [4], environmental monitoring and LIDAR [5], just to a name few.

Zahra Eslami

Papers

Carcinogenic and non-carcinogenic risk assessment induced by pesticide residues in honey of Iran based on Monte Carlo Simulation

Low-Noise Octave Spanning Mid-Infrared Supercontinuum Generation in a Large Core Chalcogenide Fiber

Low noise mid-infrared supercontinuum generation in multimode chalcogenide fiber (Conference Presentation)

Octave-spanning Infrared Supercontinuum Generation in a Graded-Index Multimode Lead-Bismuth-Gallate Fiber

High-Power Short-Wavelength Infrared Supercontinuum Generation in a Multimode Fluoride Fiber