ANALYTICAL REPRESENTATIONS FOR THE TRUNCATED SPECTRAL CHARACTERISTICS OF THE FOUR-POINT COHERENCE FUNCTION OF A LASER BEAM IN A TURBULENT MEDIUM

2021 ◽  
Vol 88 (6) ◽  
pp. 872-880
Author(s):  
N. N. Rogovtsov ◽  
V. Ya. Anissimov
Keyword(s):  
Functional Equation ◽  
Refractive Index ◽  
Laser Beam ◽  
Spectral Characteristic ◽  
Spectral Characteristics ◽  
Coherence Function ◽  
Turbulent Medium ◽  
Analytical Expressions

New analytical representations for the truncated spectral characteristics of the four-point coherence function of a laser beam propagating in a turbulent medium are obtained. These representations are valid for any level of fluctuations of the refractive index in air. For two particular cases they turn into exact analytical representations previously derived by the authors with using of an integro-functional equation for truncated spectral characteristic of the four-point coherence function. A constructive procedure for obtaining approximate analytical expressions of the four-point coherence function of a laser beam propagating in a turbulent medium is proposed.

Relativistic self-focusing of a rippled laser beam in a plasma

1999 ◽  
Vol 62 (4) ◽  
pp. 389-396 ◽  
Author(s):  
M. V. ASTHANA ◽  
A. GIULIETTI ◽  
DINESH VARSHNEY ◽  
M. S. SODHA
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
The Self ◽  
Laser Beams ◽  
Radial Dependence ◽  
Main Beam ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Saturation Effects ◽  
Paraxial Ray

This paper presents an analysis of the relativistic self-focusing of a rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is studied for arbitrary magnitude of nonlinearity. Pandey et al. [Phys. Fluids82, 1221 (1990)] have shown that a small ripple on the axis of the main beam grows very rapidly with distance of propagation as compared with the self-focusing of the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation effects of nonlinearity allow the nonlinear refractive index in the paraxial regime to have a slower radial dependence, and thus the ripple extracts relatively less energy from its neighbourhood.

scholarly journals NONLINEAR OPTICAL WAVEGUIDE STRUCTURE FOR SENSOR APPLICATION: TM CASE

2007 ◽  
Vol 21 (30) ◽  
pp. 5075-5089 ◽  
Author(s):  
HALA M. KHALIL ◽  
MOHAMMED M. SHABAT ◽  
SOFYAN A. TAYA ◽  
MAZEN M. ABADLA
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Closed Form ◽  
Optical Waveguide ◽  
Effective Refractive Index ◽  
Nonlinear Optical ◽  
Waveguide Structure ◽  
Analytical Expressions ◽  
Evanescent Waveguide ◽  
Waveguide Sensor

In this work, we present an extensive theoretical analysis of nonlinear optical waveguide sensor. The waveguide under consideration consists of a thin dielectrica film surrounded by a self-focused nonlinear cladding and a linear substrate. The nonlinearity of the cladding is considered to be of Kerr-type. Both cases, when the effective refractive index is greater and when it is smaller than the index of the guiding layer, are discussed. The sensitivity of the effective refractive index to any change in the cladding index in evanescent optical waveguide sensor is derived for TM modes. Closed form analytical expressions and normalized charts are given to provide the conditions required for the sensor to exhibit its maximum sensitivity. The results are compared with those of the well-known linear evanescent waveguide sensors.

scholarly journals General solutions of the theme “Light propagation in optical uniaxial crystals”

2017 ◽  
Vol 1 (T3) ◽  
pp. 79-89
Author(s):  
Nghia Quang Truong ◽  
Huong Tu Ngoc Nguyen
Keyword(s):  
Refractive Index ◽  
Light Propagation ◽  
New Approach ◽  
General Solutions ◽  
To Receive ◽  
Analytical Expressions

In this article, we introduce a new approach to receive general solutions which describe all of the properties of the light propagating across optical uniaxial crystals. In our approach we do not use the conception of refractive index ellipsoid as being done in references. The solutions are given in analytical expressions so we can handly calculate or writing a small program to compute these expressions.

scholarly journals Relativistic ponderomotive self-focusing of quadruple Gaussian laser beam in cold quantum plasma

2018 ◽  
Vol 36 (3) ◽  
pp. 353-358 ◽  
Author(s):  
Richa ◽  
Munish Aggarwal ◽  
Harish Kumar ◽  
Ranju Mahajan ◽  
Navdeep Singh Arora ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Electron Temperature ◽  
Density Perturbation ◽  
Beam Width ◽  
Quantum Plasma ◽  
Gaussian Laser Beam ◽  
Self Focusing ◽  
Linear Differential ◽  
Paraxial Ray

AbstractIn the present paper, we have investigated self-focusing of the quadruple Gaussian laser beam in underdense cold quantum plasma. The non-linearity chosen is associated with the relativistic mass effect that arises due to quiver motion of electron and electron density perturbation caused by ponderomotive force. The non-linearity modifies the plasma frequency in the dielectric function and hence the refractive index of the medium. The focusing/defocusing of the quadruple laser depends on the refractive index of the medium. We have set up non-linear differential equation that controls the beam width parameter by using well-known paraxial ray approximation and Wentzel–Krammers–Brillouin approximation. The effect of intensity parameter and electron temperature is observed on laser beam self-focusing in the presence of cold quantum plasma. From the results, it is revealed that electron temperature and the initial intensity of the laser beam control the profile dynamics of the laser beam.

Aberrations of Volume Cylindrical Holographic Optical Element

2013 ◽  
Vol 8 (3) ◽  
pp. 6-12
Author(s):  
Yuriy Batomunkuev
Keyword(s):  
Refractive Index ◽  
Characteristic Function ◽  
Optical Element ◽  
Thermally Induced ◽  
The Third ◽  
Holographic Optical Element ◽  
Seventh Order ◽  
Chromatic Aberrations ◽  
Cylindrical Volume ◽  
Analytical Expressions

The analytical expressions allowed to calculate the third-, fifth- and seventh-order monochromatic and chromatic aberrations are obtained for the cylindrical volume holographic optical element by method of the characteristic function. The formulas for coefficients of third-, fifth- and seventh-order aberrations are presented. It is noted that coefficients of the aberrations arising because of photo induced, thermally induced and deformation changes of refractive index and of sizes of the cylindrical volume holographic optical element can be isolated in these coefficients. It is shown that width of the working spectral range for reflection cylindrical volume holographic optical element is inversely proportional to its thickness and for transmission holographic element is inversely proportional to square its thickness

CORONENE ORGANIC FILMS: OPTICAL AND SPECTRAL CHARACTERISTICS UNDER ANNEALING TEMPERATURE INFLUENCES

2021 ◽  
pp. 2150081
Author(s):  
ERMAN ERDOGAN
Keyword(s):  
Refractive Index ◽  
Annealing Temperature ◽  
Film Growth ◽  
Low Cost ◽  
Spectral Characteristics ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Optical Bandgap ◽  
Dielectric Constants ◽  
Optical Parameters

In this study, spin coating, which is a chemical film layer thin film deposition method, was used for coronene films that were grown on Si substrates annealed at 325, 350 and 375[Formula: see text]K to examine the impacts on the optical properties of films. This method allows for easy control of the deposition parameters such as concentration, temperature and time as well as enables the film growth at low cost. Optical (UV–Vis) spectral measurements in the wavelength range from 200[Formula: see text]nm to 800[Formula: see text]nm were used to extract the bandgap information and to calculate various optical parameters of the spin-coated coronene films. The electronic transitions on the absorption of photons of suitable energy are of indirect allowed type. The corresponding optical bandgap ([Formula: see text]) was determined. Complex dielectric constants, dissipation factor, optical and electrical conductances and refractive index of coronene films were analyzed as a function of temperature. As the film annealing temperature was increased, the dielectric constants and the refractive index values increased, whereas the optical bandgap and electrical and optical conductivity values decreased.

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