K. Ozga

Quantum chemical simulations of solvent influence on UV–vis spectra and orbital shapes of azoderivatives of diphenylpropane-1,3-dione

The DFT modeling of novel synthesized azoderivatives of β-diketones - 2-(2-(2-hydroxyphenyl)hydrazono)-1,3-diphenylpropane-1,3-dione (1), 2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1,3-diphenylpropane-1,3-dione (2), 3-(2-(1,3-dioxo-1,3-diphenylpropan-2-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzene sulfonic acid (3), 2-(2-(1,3-dioxo-1,3-diphenylpropan-2-ylidene)hydrazinyl)benzenesulfonic acid (4), 2-(2-(1,3-dioxo-1,3-diphenylpropan -2-ylidene)hydrazinyl)benzoic acid (5), 2-(2-(2-hydroxy-4-nitrophenyl)hydrazono)-1-phenylbutane-1,3-dione (6) were performed. The collected information confirms that 1-5 exist in hydrazo form, being stabilized by the intramolecular hydrogen bonds in DMSO solution and solid phase, while 6 exists in mixed enol-azo and hydrazo tautomeric forms, the latter dominating in more polar solvents. The relative stability of various tautomeric and izomeric forms of the symmetric 1-5 and unsymmetric 6 azoderivatives of β-diketones is calculated based on the density functional theory (DFT). Polarizable Continuum Model was used to simulate solvatochromic effects. Solvents of different polarities were used to collect experimental spectra, and the same solvents were chosen for the PCM calculations. The optical properties of 1-6 have been investigated by density functional theory and its electronic absorption bands have been assigned by time-dependent density functional theory (TD-DFT).

All-optical operation by optical susceptibilities of Ca4NdO(BO3)3:Yb single crystals

We have found substantial enhancement of the optical second harmonic generation (SHG) in Ca4NdO(BO3)3:Yb (1.9% of Yb in weight units) crystals after 10 min optical treatment by the continuous wave (cw) laser at 532 nm and after 15 min treatment by blue 405 nm cw laser. Treatment by a red laser (660 nm) leads to the suppression of this effect. Principally the effect is only slightly reversible and the successive illumination of the same sample leads to the enhanced SHG, which correlates with changes in the principal absorption bands around 300–330 nm and 400–430 nm corresponding to the optical transitions between the energy levels of Nd3+ ions. The effect does not depend on the photoinducing light polarization. The principal origin of the observed photoinduced optical SHG is caused by photopolarization of the Nd localized levels and formation of the stable polarized states.

Non-Linear Optical Effects in Au Nanoparticle-Deposited ZnO Nanocrystalline Films

Applying a bicolor coherent treatment of a Nd-YAG laser with wavelength 1.32 μm and its second harmonic generation, we have investigated photoinduced SHG in Au nanoparticledeposited ZnO nanocrystallinne (NC) films. We have established that coexistence of the such crystallites gives substantially better results compared to the pure ZnO NC deposited onto the glass substrate. It was shown that the value of the second order susceptibility obtained for the large incident angles of the fundamental and writing beams is equal to about 23 pm/V. The better results are obtained during the phototreatment at temperatures near the 60 oC for the Au doped samples and is almost non-sensitive to temperature for the pure samples. The further increase of the temperature leads to decay of the optical second harmonic generation

A novel approach for tailoring structural, morphological, photoluminescence and nonlinear optical features in spray coated Cu:ZnO nanostructures via e-beam

In this article, we present the investigations on modification of structural, morphological, and optical properties of spray coated Cu doped ZnO (CZO) thin films by electron beam. Glancing angle X-ray diffraction reveal polycrystalline nature of the CZO films and indexed to hexagonal wurtzite structure. Notable reduction in FWHM values upon e-beam treatment is attributed to the irradiation induced reorientation of grains. The Gaussian deconvolution at ambient temperature photoluminescence (RTPL) spectra demonstrates broad visible bands for all the spectra which is caused by presence of various structural and native defects like oxygen, zinc, zinc interstitials and antisite oxygen defects. The increase of the electron beam dosage from 0 kGy to 20 kGy results in the decrement of the PL intensity endorsing the fact that e-beam irradiation can act as a luminescent activators which can effectively regulates the luminescence behavior of CZO thin films. The Raman spectra of CZO show a successive reduction in the intensity of Raman peaks especially for the dominant peak around ∼439 cm−1 upon e-beam treatment. Increase in localized defect states results in decreasing energy band gap magnitudes for the nanostructures. The third order nonlinear optical properties of the films have been studied using Z-scan and laser stimulated third harmonic generation technique (LITHG). Enhancement of third harmonic frequency conversion efficiency of CZO nanostructures is caused by electron beam induced photoexcitation and relaxation processes. The transition properties of saturable absorption (SA) and reverse saturable absorption (RSA) mechanism upon e-beam irradiation for the CZO films can be used for production of optical limiters, all-optical logic gates, optical triggers, mode storage and fast optical switchers etc.

Influence of pressure on optical absorption of triglycine selenium single crystals

For the first time we have shown that increasing uniaxial pressure on the triglycine selenium single crystals leads to the occurrence of several spectral maxima below the energy gap. It is principal that after interruption of the applied uniaxial pressure one observes remarkable spectral shifts up to 20 nm of the principal spectral maxima at 280 nm and 340 nm. The effect is caused by the changes of inter-molecular interactions of the van der Waals type in such kinds of crystals and occurrence of in elastic interactions. The effect has irreversible character and after applying of uniaxial pressure several times we see that there occur several strains which may be considered as the remaining infer-molecular stresses. The observed phenomenon may be used for creation of the optoelectronic tensors of the pressure with the forces up to 4 kG. The performed investigations have shown that the spectral broadening is not sensitive to the pressure, however their spectral shifts are substantially sensitive to the applied pressure. The observed effect possess a long time reversibility (up to one month). Additional studies of piezooptical effects have shown its sensitivity to the external cw green laser light at power 300 mW. Using the thermoluminescence we have established that the crystals are very sensitive to the number of trapping levels within the energy gap. Additionally there were performed studies of electrooptical effects for the pulsed 10 ns Nd:YAG laser.

Piezooptical materials doped by silver nanoparticles for telecommunications

We present a new technological approach of using the known piezooptical glasses for telecommunications by introduction of the silver nanoparticles. The main principle consists of existence of the surface plasmon resonances of the silver nanoparticles in the spectral range 480 nm - 530 nm. The latter one favors an increase of their elastooptical properties closely connected with the acoustooptical efficiencies. Principal parameters of the silver nanoparticles, e.g. their concentration, nanoparticle sizes and type of the glasses is discussed.

Acoustically operated optically transparent nanocomposites

In this report we present principal results of synthesis of different kinds of nanocrystallites incorporated into the photopolymer matrices for the operation by their parameters using acoustooptical effects. The technological details of their synthesis are given. Principal results of the acoustooptical quality versus the properties of the nanocomposites are studied. The dependences show high sensitivity of the materials to the nanocrystallite, their sizes and to the content. The possible acoustooptical modulators based on the nanocrystals incorporated into the photopolymer composites are given. Dependence on the time of UV-solidification is given.

Photopolymerized Optical Fiber Technology

A method of formation of oligoetheracrylate photo-solidified fibers is proposed. The solidification process is performed by UV-nanosecond 337 nm nitrogen laser. Using different profiles of the light masque the optical fibers with the operated birefringence are formed with averaged diameter about 80- 100 mum. Two principal mechanisms of the observed changes are discussed: reorientation of the non-solidified liquid oligoetheracrylate composites and topochemical photo-polymerization reactions. Substantial anisotropy of the transmitted polarized light at 694 nm and 1040 nm with respect of the UV-solidified beam is obtained.