Evolution of Physicochemical Properties of 2-(2-(4-(4-chloro) phenyl) vinyl)-1, 1, 3-trimethyl-1H-benzo[e] Indolium Iodide via Experimental and Quantum Chemical Calculation for Third-Harmonic Generation Applications

In this work, the authors have reported the synthesis, crystal structure, and physicochemical properties of new Indolium based nonlinear optical crystal of 2-(2-(4-(4-chloro) phenyl) vinyl)-1, 1, 3-trimethyl-1H-benzo[e] Indolium iodide. The title crystal was grown by slow evaporation technique using methanol as a solvent. The harvested crystal is subjected to the single-crystal X-ray diffraction study and found that the title crystal belongs to the monoclinic system with a space group of P21/n. The bandgap and optical window of the material are studied by UV-visible spectroscopic analysis, and the found values are 4.2 eV and 295-800 nm, respectively. The grown crystal is subjected to analyze the thermal stability and found that high-temperature stability value upto 264 oC and which is sufficient for industrial applications. Furthermore, the effect of temperature on the grown crystal dielectric properties such as dielectric constant and dielectric losses is investigated by impedance spectroscopic analysis. The molecular charge transfer on the material is studied from density functional theory. The various intermolecular interactions existence in the crystal is explored from Hirshfeld surface analysis. Finally, the Z-scan parameters expose that title crystal is a potential material for third-harmonic generation applications. The overall structural studies and functional properties disclose that the grown crystal is well suitable for harmonic generation applications.

Effects of an External Magnetic Field on the Interband and Intraband Optical Properties of an Asymmetric Biconvex Lens-Shaped Quantum Dot

The theoretical investigation of interband and intraband transitions in an asymmetric biconvex lens-shaped quantum dot are considered in the presence of an external magnetic field. The selection rules for intraband transitions are obtained. The behaviors of linear and nonlinear absorption and photoluminescence spectra are observed for different temperatures and magnetic field strengths. The second and third harmonic generation coefficients as a function of the photon energy are examined both in the absence and presence of an external magnetic field.

Third harmonic generation of a relativistic self-focusing laser in plasma under exponential density ramp

Present study focuses on self-focusing and its effect on third harmonic generation (THG) of a Gaussian laser beam in plasma under the influence of exponential density ramp. Relativistic nonlinearity has been taken into account which is aroused due the modification of electron’s mass in the presence of high intensity laser. Under strong ponderomotive force, electrons acquire very high quiver velocity and mass variation takes place. Equations for beam width parameter of incident laser and the amplitude of THG have been derived under WKB and paraxial ray approximation, and solved them numerically. It is found that the presence of exponential plasma density ramp results strong self-focusing of laser which further leads to enhance the efficiency of THG. Wiggler magnetic field adds an additional momentum to the photons of third harmonic due to which appreciable gain is observed in the normalized amplitude of THG. Significant enhancement in the THG amplitude has been reported in the presence of exponential density ramp for optimum values of intensity of incident laser, wiggler magnetic field and plasma frequency.

Third Harmonic Generation by Focusing Femtosecond Radiation with a Wavelength of 1032 nm in Air

In open publications the results of research on the third harmonic generation in the air by femtosecond laser radiation are presented. Most of the studies have been carried out using a titanium-sapphire laser with a central emission wavelength of 800 nm. This work presents for the first time the results of studies of the third harmonic generation in the air from laser radiation with a wavelength of 1032 nm. The source of the laser radiation was an ytterbium femtosecond laser which generated pulses with duration of ~ 250 fs and a repetition rate of 1 kHz. The average output power of the laser reached 1750 mW. Maximum peak intensity of excitation laser radiation was up to 10 TW/cm2. When focusing the laser radiation its filamentation took place and was accompanied by generation of the third harmonic radiation at wavelength of 344 nm. Spectral, energy and spatial characteristics of the generated third harmonic radiation were investigated. Energy measurements were carried out up to the threshold power of pump radiation at which the competing nonlinear processes in the circuit optical elements of the experimental setup began to occur. The maximum average third harmonic emission power was 1.52 mW with a third harmonic conversion efficiency of about 0.085 %. The far-field beam pattern had a symmetric Gaussian profile with a radiation divergence of 0.11 mrad which corresponds to the diffraction quality of the beam (M2 ≈ 1)