Search

Highlights • The effect of power supply parameters on the Helium emission line intensity have been investigated. • The emission line intensity increases by increasing the voltage amplitude. • The emission line intensity increases by increasing the frequency. • The emission line intensity decreases by increasing the pulse width. • The electron density and temperature have been obtained using the Stark broadening. Abstract In this work, contribution of all the broadenings in the emission line broadening in atmospheric pressure plasma jets (APPJs) have been determined for the cases of 667 nm and 728 nm lines. By fitting the experimental data with Voigt function, the experimental broadening have been obtained. By calculating Instrumental, Doppler, Resonance and Van Der Waals broadenings, and using experimental broadening, Stark broadening have been obtained. Finally, by using Griem's formula, the electron density and temperature have been determined and the effect of supply power parameters, voltage amplitude, frequency and pulse width, on the lines intensities and Stark broadening and the electron density and temperature have been investigated. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a hybrid optomechanical system consisting of two cavities, which one of them is an optomechanical cavity that includes an optical parametric amplifier (OPA) and the other is a traditional cavity which contains an atomic medium. Hamiltonian of the system is written in a rotating frame with a rotation frequency of the frequency of input field to the system. Using Heisenberg-Langevin equations of motion, the dynamics of the system is described. Applying the steady-state conditions leads to a system of equations of the mean values of the operators of the system. The stability condition of the system is satisfied numerically and behavior of optomechanical cavity is investigated in different situations to find the effect of changing of the parameters of the system on the type of its stability. We show proposed system has the capability of tristable behavior, where, the gain coefficient of OPA acts as a switch in changing the bistability of the system to a tristable manner. The building block of the tristability in this system can be figured out as the enhanced nonlinearity of the system due to the presence of OPA. [ABSTRACT FROM AUTHOR]

In this paper, nonlinear propagation of the intense ultra short pulses through under dense plasmas are investigated analytically. Using paraxial theory, the beam width parameter is evaluated as a function of the propagation distance. The effect of the inertial ponderomotive force, ρ m ( u → ⋅ ∇ → )   u → , on intensity of the second harmonic pulse and self focusing of laser pulse are considered. It is shown that the second harmonic amplitude depends on the propagation distance periodically. It is shown that the inertial ponderomotive force affects efficiency of the second harmonic generation, but it does not affect beam width parameter of the second harmonic wave. [ABSTRACT FROM AUTHOR]

In this paper, effect of the control lasers detuning on generation of the double window and also full width half maximum (FWHM) of electromagnetically induced transparency (EIT) are investigated. The quantum system is a W-type 4-level GaAs cylindrical quantum dot (QD) with parabolic potential. The Schrödinger equation is solved in method of effective mass. Using obtained eigen functions and eigenvalues, susceptibility of cylindrical QD is found. Dependence of electromagnetically induced transparency on the probe and control lasers detuning, radius and height of cylindrical QD, polarization and amplitudes of probe and control lasers are also investigated. [ABSTRACT FROM AUTHOR]

The sum-frequency generation (SFG) is theoretically studied in a quantum dot (QD) through the framework of the effective-mass approximation and compact density matrix approach. QD is spherical with the parabolic potential confinement, under applied electric field and in the presence of Rashba spin-orbit interaction (SOI). Using the computed energies and eigenkets, the second-order susceptibility of SFG has been also calculated as a function of radius of QD, spin–orbit interaction strength and the applied electric field. The effects of Rashba SOI strength, radius of QD and the applied electric field on the second-order of susceptibility coefficient are considered. [ABSTRACT FROM AUTHOR]

Abstract: The propagation of magnetoacoustic solitary waves is investigated in magnetized quantum plasma consisting of cold ions and hot electrons. By using the quantum magnetohydrodynamic (QMHD) model, the nonlinear characteristics of different features of solitary waves in an electron-ion quantum magnetoplasma are investigated. Magnetoacoustic solitary waves are stationary solutions of the equations composed of the nonlinear mass and momentum continuity, together with the Maxwell's equations. The important quantum-mechanical effects including the quantum statistical and diffraction are examined numerically on the profiles of the solitons. It is found that the non-dimensional characteristic of the quantum parameter plays a significant role in the formation of the solitons. [Copyright &y& Elsevier]

Abstract: In this paper, by considering a weakly relativistic case and using the hydrodynamics fluid equations in plasma and Maxwell's equations, the general equation for the wake potential is obtained. The analytical solutions of the wake potential are gotten for Gaussian-like (GL) and rectangular–triangular (RT) pulses in presence and absence of magnetic field. It is shown that the wake field depends on length and wavelength of pulses, electron number density of plasma and external magnetic field. The effect of magnetic field on the production of the wake field is also considered. [Copyright &y& Elsevier]

Abstract: In this paper, we have investigated the electron Raman scattering in a spherical quantum dot with parabolic confinement and in presence of uniform magnetic field. By solving the Schrödinger equation in effective mass and envelope function approximations, eigen-functions and eigen-energies and laws of transitions are acquired. By using eigen-functions and eigen-energies, the differential cross-section (DCS) of electron Raman scattering (ERS) is obtained. DCS is plotted a function of scattering frequency, for different transitions, emission light polarization and sizes of quantum dot. [Copyright &y& Elsevier]

Abstract: In this paper, fiber-optic sensor based on surface plasmon resonance (SPR) is considered. The fiber-optic sensor is coated with thin nanoparticle metallic films. The nanoparticle metallic film consists of spherical metallic nanoparticles embedded in a host material. It is shown that sensitivity and absorption of sensor depends on number and type of films. It theoretically analyzed that the different states such as, fiber-optic sensor with a single thin layer of spherical gold or silver nanoparticle and a bimetallic arrangement of silver and gold nanoparticles. It also studied dependence of the sensitivity and absorption of sensor on the parameters such as gold particle size, film thickness, refractive index of host material, sensing region length, fiber core diameter, maximum absorption wavelength, half maximum width of the sensing medium and background refractive index of the sensing layer. [Copyright &y& Elsevier]

Abstract: In this paper, by using the hydrodynamics fluid equations in underdense plasma and Maxwell''s equations, the general equation for the wake potential, which can be directly used for different envelopes of optical laser pulse, is obtained. The analytical solution of the equation for the Gaussian short-intense laser pulse is also acquired. It is shown that the wake field, which leads to electron acceleration, depends on intensity, length, frequency and energy of pulse and the electron number density. We also investigate the generation of wake field and the energy gain acquired by an electron in the plasma in the presence or absence of external magnetic field. It is shown that the efficiency of wake field is increased in the presence of an external magnetic field. [Copyright &y& Elsevier]

Abstract: The sum-frequency generation (SFG) in a quantum dot (QD) is theoretically studied through the framework of the effective-mass approximation and using the perturbation method and compact density matrix approach. QD is spherical with the parabolic confinement, under applied electric field. By using the computed energies and wave functions, the second-order susceptibility of SFG is also calculated as a function of confinement strength, radius of QD and the applied electric field. The results show that the second-order susceptibility of SFG are strongly affected by the confinement strength, external applied electric field and radius of QD. It is shown that the binding energies are highly dependent on the quantum confinement. [Copyright &y& Elsevier]

Abstract: In this paper, we consider the process of sum frequency generation (SFG) in an underdense plasma in the presence of a wiggler magnetic field. It is shown that the presence of magnetic field leads to generate not only the even-order nonlinear phenomena such as transversal sum frequency waves but also longitudinal waves at fundamental and sum frequencies. It is also revealed that the wave vector of wiggler magnetic field acts as a virtual photon of quantum energy zero and momentum so that phase-matching condition is provided by the conservation of the momentum. Efficiency of the sum frequency generation is considered at different intensities, frequencies and number densities. [ABSTRACT FROM AUTHOR]

In this paper electromagnetically induced transparency (ELT) is investigated in a four- level M-type spherical quantum dot (SQD) in the vicinity of spherical metal nanoparticle (SMNP) by using Mie theory. The schrodinger equation is solved to obtain eigenstates and eigenvalue of the SQD. Then, using obtained eigenstates and eigenvalues of the SQD and solving equations of the density matrix elements of the system, we calculate the electric susceptibility of the SQD. Finally, dependence of EIT on different values of the system parameters are investigated. [ABSTRACT FROM AUTHOR]