Cosh Gaussian Research Articles

Advanced electron acceleration via chirped Hermite–Cosh–Gaussian laser and magnetic field interaction

Advanced electron acceleration via chirped Hermite–Cosh–Gaussian laser and magnetic field interaction

Second Harmonic Generation of High Power Cosh-Gaussian Beam in Thermal Quantum Plasma: Effect of Relativistic and Ponderomotive Nonlinearity

Second harmonic generation (SHG) of high power Cosh-Gaussian(ChG) beam in thermal quantum plasma (TQP) is explored in current investigation. Relativistic and ponderomotive nonlinearities are taken together in present investigation. Combination of relativistic-ponderomotive nonlinearities causes modification in electron mass, thereby producing density gradients inside plasma. This further produces self-focusing of main beam. The well-known WKB and paraxial approaches are used for solving main beam’s wave equation and to obtain 2nd order ordinary differential equation (ODE). There is generation of electron plasma wave (EPW) due to these density gradients. Excited EPW interacts with main beam to generate 2nd harmonics in plasma. Effects of combined relativistic-ponderomotive nonlinearities and established laser - plasma parameters on beam’s waist and SHG yield are studied in present study.

Impact of High-Power Cosh-Gaussian Beam on Second Harmonic Generation in Collisionless Magnetoplasma

The impact of high power Cosh-Gaussian (ChG) beam on Second harmonic generation (SHG) in Collisionless magnetoplasma is explored in present work. Whenever the input beam propagates along external magnetic magnetic field direction, then there are two propagation modes viz. extraordinary mode and ordinary mode. The modification in magnetic field strength causes redistribution of carriers. The density gradients get established in plasma in a normal direction to input wave due to ponderomotive force. Further, there is production of electron plasma wave (EPW) at input wave frequency due to density gradients. EPW nonlinearly interacts with pump wave causing generation of 2nd harmonics. The 2nd order differential equation (ODE) for beam width of and efficiency of 2nd harmonics are derived through well-known paraxial theory approach. RK4 method is employed for carrying out numerical calculation of nonlinear ODE along with efficiency of 2nd harmonics. Impact of change in selective laserplasma parameters and externally applied magnetic field on beam waist of input wave and efficiency of SHG are also explored.

THz radiation generation in the unmagnetized plasma due to beating of two Hermite Cosh Gaussian lasers in the presence of frequency chirp

THz radiation generation in the unmagnetized plasma due to beating of two Hermite Cosh Gaussian lasers in the presence of frequency chirp

Self-focusing of skew cosh gaussian laser beams propagation in absorbing collisionless and collisional plasmas

Self-focusing of skew cosh gaussian laser beams propagation in absorbing collisionless and collisional plasmas

Performance analysis of Sinh and Cosh Gaussian vortex beam in vertical underwater optical communication

The performance analysis of Sinh Gaussian vortex beam (ShGvB) and Cosh Gaussian vortex beam (ChGvB) in oceanic turbulence is established by employing an anisotropic spatial power spectrum that considers the influence of the ocean depth to mimic the actual oceanic conditions. Since the salinity and temperature variations along depth are not linear, the actual data of temperature and salinity measured from the tropical region of the ocean is used for the current study. The propagation properties of the ShGvB are studied by deriving the cross-spectral density of the beam, and the average intensity of the beam is plotted over depth and studied in both isotropic and anisotropic oceanic turbulence systems. The analysis of the beam spot radius shows that the beam degrades faster in anisotropic media than in isotropic media. Quantitative estimation of the detection probability, channel capacity and bit error rate (BER) have been made to evaluate the beam's performance for vertical underwater optical communication. The BER may be improved by enlarging the detector aperture radius and signal-to-noise ratio. The ShGvB performs effectively in vertical underwater optical communication compared to the ChGvB.

Far IR field generation by mixing of cosh-Gaussian and dark hollow Gaussian laser in encapsulated plasma

A scheme of laser-plasma interaction is proposed by mixing of Cosh Gaussian (ChG) and Dark Hollow Gaussian (DHG) laser in rippled density plasma when an external periodic electric field wiggler is applied because of the emission of far infrared field lying in the terahertz frequency regime. The unusual mixing of ChG and DHG laser broadens the field of THz radiation from unifocal to multifocal by controlling beam order and decentralized parameters. Moreover, the wiggler field wavenumber provides two additional resonance conditions, which govern the emission of multiple components of far IR field resonantly that may have extensive medical applications. The field amplitude of such emissions and their efficiency may be increased manifold. Moreover, the efficiency can be increased several times if parallel plates are placed with a few nanometers of separation.

Electron accelerataion by laser driven electron plasma wave in plasma with axial density ramp: Cosh Gaussian laser beam

Electron accelerataion by laser driven electron plasma wave in plasma with axial density ramp: Cosh Gaussian laser beam

Frequency doubling on a metallic surface by Hermite–Cosh–Gaussian laser beam

Frequency doubling on a metallic surface by Hermite–Cosh–Gaussian laser beam

A theoretical study of spectral properties of generalized chirped Hermite cosh Gaussian pulse beams in oceanic turbulence

A theoretical study of spectral properties of generalized chirped Hermite cosh Gaussian pulse beams in oceanic turbulence

Spectrum changes of pulsed chirped Generalized Hermite cosh-Gaussian beam through turbulent biological tissues

The main objective of this study is to investigate the development of the spectral intensity profile of a pulsed chirped Generalized Hermite cosh Gaussian (GHCG) beam through turbulent biological tissues. This is achieved using Schmitt's model for the power spectrum refractive index, the extended Huygens-Fresnel integral, and the Fourier Transform method. Graphical representations need to be generated to explore the effects of beam parameters and biological turbulence parameters on the considered beam. Furthermore, a thorough discussion is conducted to examine the influence of both optical parameters and biological tissue characteristics on spectral shifts at various observation positions. The findings hold potential applications in image recognition, medical devices, and the noninvasive optical diagnosis of biological tissue.

Study of propagation of skew cosh Gaussian laser beam in attenuated magneto plasma

Self-focusing of a laser beam is one of the major consequences of nonlinear interaction of laser with plasma. In this paper, self-focusing of skew cosh Gaussian (skew-ChG) laser beam is studied in anisotropic, collisional plasma where in externally exponentially decreasing magnetic field is applied. Skewness parameters in the field profile of skew-ChG laser beam eventually determine intensity profile of the beam. The symmetry in skewness parameter in two transverse directions simplifies the calculations considerably. Second order, nonlinear, ordinary, coupled differential equations for Beam Width Parameters (BWP) are obtained using Akhmanovs approach under Wentzel–Kramers–Brillouin (WKB) and paraxial approximations which are solved numerically. For given amplitude of applied magnetic field, attenuated oscillatory self-focusing is observed with respect to change in attenuation coefficient.

Influence of self-focused high power Cosh-Gaussian beam on second harmonic generation in cold quantum plasma

The objective of present work is to investigate influence of self-focused high power Cosh-Gaussian (ChG) beam on second harmonic generation (SHG) in cold quantum plasma (CQP). WKB and Paraxial approximations are utilized for acquiring 2nd order differential equation representing propagation characteristics of ChG beam with normalized propagation distance. The modification in dielectric function of plasma is observed on account of relativistic nonlinearity causing self-focusing of ChG beam. The density gradients are produced in transverse direction. These density gradients cause electron plasma wave (EPW) excitation at main wave frequency. Further, the nonlinear interaction between pump wave and excited EPW produces 2nd harmonics in plasma. We have performed numerical simulations for exploring impact of various laser & plasma parameters on beam waist of ChG beam and conversion efficiency of 2nd harmonics. We have also made the comparison of given work with classical relativistic plasma (CRP) regime.

Electron plasma wave excitation by self-focused cosh gaussian laser beams in axially inhomogeneous plasma: effect of density ramp

Electron plasma wave excitation by self-focused cosh gaussian laser beams in axially inhomogeneous plasma: effect of density ramp

Cosh-Gaussian laser pulse influenced electron acceleration in an ion channel

The electron acceleration in a prepared ion channel is studied theoretically by using a radially polarized (RP) cosh-Gaussian (ChG) laser pulse. The peculiar propagation properties of ChG laser cause it to focus early and over a shorter time than a Gaussian laser pulse, making it suitable for accelerating electrons to extremely high energies over a small duration. The electrostatic field formed by an ion channel prevents electrons from escaping the interaction zone due to their transverse oscillations, whereas the decentering parameter of the ChG laser pulse influences electron energy gain. This combined role of RP-ChG laser and the effect of an ion channel causes an enhancement in the electron energy gain significantly to the order of GeV with laser intensity (∼) in an ion density channel (∼) with decentered parameter (∼2.15) for an incident laser pulse at initial phase ().

Terahertz Radiation Generation by Frequency Mixing of Hermite–Cosh–Gaussian Laser Beams in Density-Modulated Cold Magnetized Plasma

We report a theoretical investigation for extremely bright terahertz (THz) radiation generation by mixing of dichromatic Hermite–Cosh–Gaussian (HChG) laser beams in periodically rippled density plasma in the presence of external dc magnetic field. The magnetic field is applied perpendicular to the direction of propagation and to the polarization states of laser beams. THz field amplitude significantly increases with applied dc magnetic field. Our investigations reveal that frequency resonance shifts with the applied magnetic field. As a result, THz frequency tuning is possible with applied magnetic field. The electron neutral collisions have no effect on resonance condition but THz amplitude and efficiency decreases with increase in frequency of electron neutral collisions. We find that THz field profile strongly depends on laser parameters like Cosh decentred parameter $b$ and order of Hermite function $s$ , and independent of applied magnetic field. Our theoretical investigations predict that GV/m THz field with efficiency ~7% for laser field ~50 GV/m and 80-kG applied dc magnetic field can be obtained for optimized set of laser and plasma parameters.

Excitation of lower hybrid wave by counterpropagating cosh Gaussian laser beams in a magnetized plasma

This paper presents a scheme for the excitation of lower hybrid wave (LHW) by beating of two counterpropagating cosh Gaussian (ChG) laser beams in a magnetized plasma. The beating wave having frequency ω=(ω1-ω2) and wave vector k→=k→1+k→2, exerts a pondermotive force on electrons and drive lower hybrid wave in both homogeneous and inhomogeneous plasma. The driver wave acts as a pump wave for the excitation of the lower hybrid wave. We study the variation of the normalized potential and power distribution with respect to normalized frequency under resonance conditions. The appearance of peaks shows the excitation of the lower hybrid waves. The decentred parameter and beamwidth profile of ChG laser beams play an important role in shifting the characteristics of peaks. In results, we also discuss the convective losses, escaping, and trapping conditions of waves in the magnetized plasma.

Self-Focusing of Hermite–Cosh–Gaussian Laser Beams in a Plasma Under a Weakly Relativistic and Ponderomotive Regime

In the theoretical investigation of the self-focusing of elegant Hermite–Cosh–Gaussian (EHChG) beams, the crucial role of decentered parameters has been explored thoroughly in the case of the weak relativistic and ponderomotive regime of interaction. In the present study, the Cartesian coordinate system has been employed, which enables us to study the evolution of two transverse beam-width parameters simultaneously. The differential equations for the beam-width parameters are set up through the parabolic wave equation approach by following WKB and paraxial approximations.

Radially polarized terahertz (THz) generation by frequency difference of Hermite Cosh Gaussian lasers in hot electron-collisional plasma

We report a scheme to generate radially polarized THz radiation by frequency difference of Hermite Cosh Gaussian lasers in hot electron, collisional and density modulated plasma. The effect of laser (spatial field distribution) and plasma parameters (plasma density structure, electron-neutral collisions and electron temperature) on emitted THz field profile is investigated. We found that THz field profile varies with spatial intensity profile of pump lasers. The THz amplitude increases with the pump laser intensity gradient. Our investigations show that electron collisions attenuate the THz amplitude without affecting the THz field profile. The highest THz field and conversion efficiency are obtained at resonance condition i.e. ω1−ω2≈ωp. Off-resonant excitation of THz radiation is also observed with less THz amplitude. Our investigations also reveal that the value of THz- fieldpeak and efficiency increase monotonically with electron thermal velocity (electron temperature). A high THz field (~ GV/m) and conversion efficiency ~ 0.08 can be obtained for optimized pump laser and plasma parameters.

Non‐paraxial theory of self‐focusing/defocusing of Hermite cosh Gaussian laser beam in rippled density plasmas

AbstractPresent research work focuses on study of self‐focusing and self‐trapping of Hermite cosh Gaussian (HchG) laser beams in rippled density plasma by considering relativistic non‐linearity. The coupled non‐linear differential equations for the beam width parameters (for modes m = 0, 1, and 2) were derived by employing higher‐order correction in comparison to paraxial ray theory by expanding dielectric function and eikonal up to r4 terms. It is observed that the inclusion of higher‐order terms significantly influence the off‐axial properties for m ≥ 1 mode indices. Furthermore, the effect of parameters including beam intensity, ripple factor, depth of density modulation, and decentred parameter on self‐focusing and self‐trapping is analysed and discussed both analytically and numerically.