Search results for " Optics"

Measurement of the soliton number in guiding media through continuum generation.

2020

No general approach is available yet to measure directly the ratio between chromatic dispersion and the nonlinear coefficient, and hence the soliton number for a given optical pulse, in an arbitrary guiding medium. Here we solve this problem using continuum generation. We experimentally demonstrate our method in polarization-maintaining and single-mode fibers with positive and negative chromatic dispersion. Our technique also offers new opportunities to determine the chromatic dispersion of guiding media over a broad spectral range while pumping at a fixed wavelength. (C) 2020 Optical Society of America

Simultaneous polarization attraction and Raman amplification of a light beam in optical fibers

2012

International audience; In this paper, we demonstrate that it is possible to combine both Raman amplification and polarization attraction of a signal wave in a single optical fiber by means of a counterpropagating scheme. Experiments were performed near 1550 nm in a continuous wave regime and by means of a 10 Gbit ∕ s return-to-zero signal injected in a 20 kmlong low polarization mode dispersion optical fiber. Complete repolarization and 6.7 dB amplification of the signal wave was achieved by injecting a 850 mW, 1480 nm counterpropagating polarized pump wave.

Even harmonic pulse train generation by cross-polarization-modulation seeded instability in optical fibers

2012

International audience; We show that, by properly adjusting the relative state of polarization of the pump and of a weak modulation, with a frequency such that at least one of its even harmonics falls within the band of modulation instability, one obtains a fully modulated wave at the second or higher even harmonic of the initial modulation. An application of this principle to the generation of a 80-GHz optical pulse train with high extinction ratio from a 40-GHz weakly modulated pump is experimentally demonstrated using a nonzero dispersion shifted fiber in the telecom C band.

NONLINEAR OPTICS Nonlinear virtues of multimode fibre

2015

The finding that multimode optical bres support a rich and complex mix of spatial and temporal nonlinear phenomena could yield a plethora of promising applications.

Long-transient conoscopic pattern technique

1999

0038-1098; Recent results on laser induced anisotropy in terbium gallium garnet are extended to the dynamic regime. We observed that the characteristic conoscopic pattern formation time presents a quadratic dependence on the beam size. The observed pattern intensity is accounted for by a simple analytical formula. The transient refractive index change due to thermal stress in the terbium gallium garnet is determined. (C) 1999 Elsevier Science Ltd. All rights reserved.

Insight into mechanisms of creatinine optical sensing using fluorescein-gold complex

2022

Abstract Creatinine level in biological fluids is a clinically relevant parameter to monitor vital functions and it is well assessed that measuring creatinine levels in the human body can be of great utility to evaluate renal, muscular, or thyroid dysfunctions. The accurate detection of creatinine levels may have a critical role in providing information on health status and represents a tool for the early diagnosis of severe pathologies. Among different methods for creatinine detection that have been introduced and that are evolving with increasing speed, fluorescence-based and colorimetric sensors represent one of the best alternatives, thanks to their affordability, sensitivity and easy r…

Confocal optical techniques to study channel waveguides in LiNbO3

2008

Properties of Gd-Doped Sol-Gel Silica Glass Radioluminescence under Electron Beams

2022

International audience; The radiation-induced emission (RIE) of Gd3+-doped sol–gel silica glass has been shown to have suitable properties for use in the dosimetry of beams of ionizing radiation in applications such as radiotherapy. Linear electron accelerators are commonly used as clinical radiotherapy beams, and in this paper, the RIE properties were investigated under electron irradiation. A monochromator setup was used to investigate the light properties in selected narrow wavelength regions, and a spectrometer setup was used to measure the optical emission spectra in various test configurations. The RIE output as a function of depth in acrylic was measured and compared with a reference…

Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy

2021

The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…

On some partial data Calderón type problems with mixed boundary conditions

2021

In this article we consider the simultaneous recovery of bulk and boundary potentials in (degenerate) elliptic equations modelling (degenerate) conducting media with inaccessible boundaries. This connects local and nonlocal Calderón type problems. We prove two main results on these type of problems: On the one hand, we derive simultaneous bulk and boundary Runge approximation results. Building on these, we deduce uniqueness for localized bulk and boundary potentials. On the other hand, we construct a family of CGO solutions associated with the corresponding equations. These allow us to deduce uniqueness results for arbitrary bounded, not necessarily localized bulk and boundary potentials. T…