Spectroscopie transformée de Fourier et Stark des molécules linéaires OCS et DCCCN

Doctorat en sciences physiques -- UCL, 199

Simple Analytical Expression of the Voigt Profile

This work examines several analytical evaluations of the Voigt profile, which is a convolution of the Gaussian and Lorentzian profiles, theoretically and numerically. Mathematical derivations are performed concisely to illustrate some closed forms of the considered profile. A representation in terms of special function and a simple and interesting approximation of the Voigt function are well demonstrated, which could have promising applications in several fields of physics, e.g., atmospheric radiative transfer, neutron reactions, molecular spectroscopy, plasma waves, and astrophysical spectroscopy

Influence of maritime turbulence on the spectral changes of pulsed Laguerre higher-order cosh-Gaussian beam

peer reviewedThis study investigates the propagation of a pulsed Laguerre higher-order cosh-Gaussian beam in turbulent maritime environments. Using the extended Huygens-Fresnel principle and the Fourier Transform method, we derive the formula for beam propagation in a marine environment. The analysis includes the influence of maritime turbulence, transverse positions, and initial beam parameters on the spectral intensity of the propagated beam. Graphical representations illustrate these effects, and numerical calculations demonstrate the relative spectral shift at various radial coordinates. The findings reveal dependencies on the refractive index structure constant, pulse duration, and beam order. Notably, on-axis spectral intensity experiences a blue shift, while off-axis spectral intensity undergoes a red shift with increasing radial coordinate. The study also highlights specific cases of the considered beam, providing valuable insights for information coding and transmission applications

Numerical investigation of performance of mirrored Bessel beam in turbulence

We study scintillation and bit error rate performance of mirrored Bessel beams through turbulent atmosphere in this article. We beneft from numerical method to model the atmosphere. Since scintillation plays a vital role in optical wireless applications, reduction in this term provides better performance in these systems. Related with this, our results indicate that it is possible to decrease scintillation by increasing beam order to three when strong turbulent conditions are satisfed. In addition, we observe that argument of Bessel beam has more dominant role than beam order in moderate turbulence. Lastly, mirroring brings us a slight advantage in case of bit error rate. Results of this study can be benefcial for optical link designer

Performing the Finite Energy Airy-Hermite-Hollow Gaussian Beam in a turbulent atmosphere

peer reviewe

Propagation Characteristics of a Partially Coherent Gaussian Schell-model Array Vortex Beam in the Joint Turbulence Effect of a Jet Engine and Atmosphere

This work investigates the joint effects of jet engine exhaust-induced turbulence and atmospheric turbulence on the propagation of a partially coherent Gaussian Schell-model Array (GSMA) vortex beam. Using the two-process propagation method, analytical formulae are derived for the cross-spectral density, spectral density, degree of coherence, and beam width of the considered beam. The results show that the considered beam takes different shapes; when the spatial coherence is large, the spectral density of the GSMA vortex beam takes an elliptical shape, whereas when the spatial coherence is smaller, the spectral density remains a Gaussian shape. The evolution profile of the degree of coherence weakens gradually when the propagation distance, topological charge, and turbulence strength increase. Moreover, the profile of the degree of coherence takes the Gaussian profile when the propagation distance is longer or turbulence atmospheric is stronger. Furthermore, the results reveal that the corresponding beam spreads faster with a larger propagation distance, lower spatial coherence, and high-strength turbulence. This study also concludes from the results that the beam is affected more when its propagation is near the jet engine exhaust, which means that this latter has a significant impact

Atmospheric turbulent effects on the propagation properties of a general model vortex higher-order Cosh-Gaussian beam

The propagation properties for a General Model vortex Higher-order cosh-Gaussian beam (GMvHchGB) propagating in a turbulent atmosphere studied in detail. Based on the Huygens-Fresnel diffraction principle, the analytical formula of the intensity evolution for the considered beam traveling in turbulent atmosphere is derived at various propagation distances. The derived equation provides a general convenient procedure to describe the propagation characteristics to some particular beams travelling through free space/atmospheric turbulence such as a fundamental Gaussian, Cosh-Gaussian, vortex Cosh-Gaussian and higher-order Cosh-Gaussian beams. The impact of the incident parameters as Gaussian waist, Cosh parameter, wavelength, hollowness and order of the beam are numerically verified. Our study proven that the beams maintain their intensity focused over long propagation distances. Therefore, they will be useful in long-distance free-space optical communication applications

Impact of human upper dermis tissue on the spectral intensity of a pulsed chirped general model vortex higher‑order cosh‑Gaussian beam

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Fourier transform spectroscopy of carbonyl sulfide from 4800 to 8000 cm–1 and new global analysis of 16O12C32S

We have measured the FT spectrum of natural OCS from 4800 to 8000 cm-1 with a near Doppler resolution and a line-position accuracy between 2 and 8 × 10-4 cm-1. For the normal isotopic species 16O12C32S, 37 vibrational transitions have been analyzed for both frequencies and intensities. We also report six bands of 16O13C34S, five bands of 16O13C32S, two bands of 16O12C33S, and two bands of 18O12C32S. Important effective Herman-Wallis terms are explained by the anharmonic resonances between closely spaced states. As those results complete the study of the Fourier transform spectra of natural carbonyl sulfide from 1800 to 8000 cm-1, a new global rovibrational analysis of 16O12C32S has been performed. We have determined a set of 148 molecular parameters, and a statistical agreement is obtained with all the available experimental data. © 1998 Academic Press.info:eu-repo/semantics/publishe

Hermite–Gaussian beams in the generalized Lorenz–Mie theory through finite–series Laguerre–Gaussian beam shape coefficients

International audienceScalar Hermite–Gaussian beams (HGBs) are natural higher-order solutions to the paraxial wave equation in Cartesian coordinates. Their particular shapes make them a valuable tool in the domain of light–matter interaction. Describing these beams in the generalized Lorenz–Mie theory (GLMT) requires a set of beam shape coefficients (BSCs), which may be quite challenging to evaluate. Since their exact analytic form expressions are unlikely to be found in the foreseeable future, we resort to a particular set of strategies. The main idea is to write HGBs as combinations of Laguerre–Gaussian beams (LGBs), which have already been studied in the GLMT framework by using a finite-series algorithm. This paper describes how to deduce the HGB BSCs directly from LGB BSCs, analyzes their behavior, and compares the resulting GLMT-remodeled solutions with their ideal paraxial counterparts