Order Nonlinear Absorption Coefficient Research Articles

Second and third order nonlinear optical studies of a novel thiophene substituted chalcone derivative

A noncentrosymmetric chalcone derivative (E)-1-(thiophen-2-yl)-3-(3, 4, 5-trimethoxyphenyl) prop-2-en-1-one (TTMP) was synthesized using Claisen Schmidt condensation approach and single crystals were grown using slow evaporation method. The grown TTMP crystals crystallizes in orthorhombic structure with Pna21 space group. The intermolecular interactions of the TTMP crystals were envisioned by Hirshfeld surface analysis (HSA). Further, the structural conformations of the crystal were carried out by using 1H NMR, FTIR, and FT-Raman spectral analysis. The UV–Vis–NIR spectrum of the sample clearly shows the prime transparency in the entire visible and near infrared region. Thermal studies (TG/DTA/DSC) of the TTMP sample shows excellent thermal stability and phase transition and also noticed that crystal was most stable up to 152.65 °C. The second harmonic generation efficiency was obtained for the crystals using Nd:YAG laser and is to be 1.93 times that of urea. The third order nonlinear absorption coefficient (β), nonlinear refractive index (n2), third-order nonlinear susceptibilities (χ (3)), second order hyper polarizability (γh) and optical limiting thresholds were determined by Z-scan technique using the Diode-Pumped Solid State (DPSS) Continuous Wave (CW) laser. The results suggest that the TTMP molecules are promising materials for optoelectronic device applications.

Spectroscopic and nonlinear optical properties of alkyl thio substituted binuclear phthalocyanines

This work presents the spectroscopic and nonlinear optical properties of metal free binuclear and monomeric 4-(pentylthio)phthalocyanine and cobalt 4,5-(bipentylthio)phthalocyanine. Second order nonlinear absorption coefficient (β) values for the complexes were determined and compared.

Synthesis, optical, experimental and theoretical investigation of third order nonlinear optical properties of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate single crystal

Single crystals of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate (8HQNP) were obtained from slow evaporation solution growth method using methanol-water (1:1) as a solvent. Powder X-ray diffraction was utilized to compute the unit cell parameters and dislocation density of 8HQNP crystal. The crystalline perfection of the as-grown crystal was investigated by high-resolution X-ray diffraction at room temperature. The molecular structure was analyzed by identifying the functional groups from FT-IR and FT-Raman spectra. The cut-off wavelength and the corresponding optical band gap obtained from an optical spectrum were 376 nm and 3.29 eV respectively. The dispersion nature of refractive index was investigated by the single-oscillator Wemple and Di-Domenico model. Red emission was observed in the photoluminescence spectrum when excited with 376 nm. The low birefringence and high laser damage threshold (8.538 GW/cm2) values dictate the suitability of the crystal for optical devices. Z-scan studies revealed the third order nonlinear absorption coefficient (β) and refractive index (n2) of the 8HQNP crystal. The theoretical value of third order nonlinear susceptibility obtained from density function theory is good accordance with the experimental value. The frontier molecular orbital energy gap decreases with increasing external electric field in different directions which attributed to the enhancement of the second hyperpolarizability. The grown title crystal is thermally stable up to 102 °C which was identified using thermal analysis. Mechanical strength of 8HQNP was estimated by using Vicker's microhardness studies.

Optical properties of the Tietz-Hua quantum well under the applied external fields

In this study, the effects of the electric and magnetic fields as well as structure parameter-γ on the total absorption coefficient, including linear and third order nonlinear absorption coefficients for the optical transitions between any two subband in the Tietz-Hua quantum well have been investigated. The optical transitions were investigated by using the density matrix formalism and the perturbation expansion method. The Tietz-Hua quantum well becomes narrower (wider) when the γ - structure parameter increases (decreases) and so the energies of the bound states will be functions of this parameter. Therefore, we can provide the red or blue shift in the peak position of the absorption coefficient by changing the strength of the electric and magnetic fields as well as the structure parameters and these results can be used to adjust and control the optical properties of the Tietz-Hua quantum well.

The effects of pressure and hydrogenic donor impurity on the linear and nonlinear optical properties of a GaAs/GaAlAs nanowire superlattice

The combined effects of hydrostatic pressure, presence and absence of hydrogenic donor impurity are investigated on the linear and nonlinear optical absorption coefficients and refractive index changes of a GaAs/Ga1−xAlxAs nanowire superlattice. The wave functions and corresponding eigenvalues are calculated using finite difference method in the framework of effective mass approximation. Analytical expressions for the linear and third order nonlinear optical absorption coefficients and refractive index changes are obtained by means of compact-density matrix formalism. The linear and third order nonlinear absorption coefficient and refractive index changes are presented as a function of photon energy for different values of hydrostatic pressure, incident photon intensity and relaxation time in the presence and absence of hydrogenic donor impurity. It is found that the linear and third order nonlinear absorption coefficients, refractive index changes and resonance energy are quite sensitive to the presence of impurity and applied hydrostatic pressure. Moreover, the saturation in optical spectrum and relaxation time can be adjusted by increasing pressure in presence of impurity whereas the effect of hydrostatic pressure is negligible in the case of absence of hydrogenic impurity.

Crystal structure and nonlinear optical properties of centrosymmetric Schiff base material: 4-Chloro-4′nitro bwenzylideneaniline

In this work one of the novel Schiff base materials, 4-chloro-4′nitro benzylideneaniline (CNBA) compound has been synthesized by the condensation reaction method and the slow evaporation solution growth technique is adopted to grow single crystals of CNBA. The three dimensional X-ray crystal structure elucidated at 173K reveals that CNBA crystallizes in the monoclinic crystal system with centrosymmetric P21/c space group. The placement of protons is identified by 1H nuclear magnetic resonance analysis. Functional groups present in the CNBA compound have been identified by Fourier transform (FT) infrared and FT Raman spectral analyses. From thermal analyses, the melting point of the CNBA material is found to be about 133°C. Linear optical properties are studied using UV–vis–NIR and fluorescence spectral analyses. Nonlinear optical properties such as powder second harmonic generation (SHG) efficiency and third order nonlinear absorption coefficient have been measured using the Kurtz and Perry method and open aperture Z-scan technique respectively. The powder SHG efficiency is found to be about 1.3 times that of potassium dihydrogen orthophosphate and the third order nonlinear absorption coefficient measured is 1.8×10−10m/W.

Laser radiation effect on the optical properties of a spherical quantum dot confined in a cylindrical nanowire

An investigation is done in order to calculate the linear, third-order nonlinear and total optical absorption coefficient and refractive index changes of an impure GaAs spherical quantum dot placed at the center of a Ga1−xAlxAs cylindrical nano-wire. In this regard, the finite difference approximation is considered to calculate electronic structure as well as compact density-matrix approach is applied to investigate optical properties. In this study the effects of laser-field radiation along with aluminum (Al) concentration on optical properties are examined for three transitions between four first lower-lying electronic levels, i.e. 1→2, 2→3 and 3→4 transitions. Also the effect of relaxation time on saturation is studied and compared for these transitions. It is found that the magnitude of linear and third order nonlinear absorption coefficient and refractive index changes as well as the optical saturation can be modified by both Al concentration and the amplitude of laser-field radiation. Moreover, for 1→2 transition (3→4 transition) the effect of quantum dot (nano-wire) is dominant whereas for 2→3 transition Al concentration is a major determinant factor. Additionally, for all transitions by increasing the value of laser field a red shift appears in optical spectrum where the extent of this red shift depends on the Al concentration and the energy levels between which the transitions occur. Finally, in contrast to QDs, a red shift appears in absorption spectrum as going up the transitions between higher energy levels.

Linear and nonlinear optical absorption coefficients and refractive index changes of a spherical quantum dot placed at the center of a cylindrical nano-wire: Effects of hydrostatic pressure and temperature

The combined effects of hydrostatic pressure and temperature on the optical absorption coefficients and refractive index changes of an InAs spherical quantum dot which is located at the center of a GaAs cylindrical nano-wire have been investigated. The wave functions and corresponding eigenvalues are calculated using finite element method in the framework of effective mass approximation. Analytical expressions for the linear and third order nonlinear optical absorption coefficients and refractive index changes are obtained by means of the compact-density matrix formalism. The linear and third order nonlinear absorption coefficient and refractive index changes are presented as a function of the photon energy, dot radius, pressure, temperature, incident photon intensity and relaxation time. It is found from our calculations that the linear and third order nonlinear optical absorption coefficients, refractive index changes and resonance energy are quite sensitive to the dot size, applied hydrostatic pressure and temperature.