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The Z-scan experiment is the fastest method to determine non-linear optical (NLO) coefficients of materials. Classic Z-scan technique described by Sheik-Bahae et al. (1989) and Wang et al. (1994) uses pulsed or CW lasers with the Gaussian beam profile. As long as the Gaussian profile is not diffused by the examined materials, this method can be used. However, by extending the classic Z-scan technique using a CCD beam profiler and analyzing the beam deviation from the Z axis, the NLO coefficients can be estimated even for a highly diffused Gaussian beam. The method proposed in this paper tracks the centroid position of the diffused beam and on this basis the two photon absorption coefficient β and the nonlinear refractive index n 2 are obtained. The accuracy depends on the samples geometry and the CCD detector used. The new approach presented in this paper can be used in substitution to the classic technique for the materials which strongly diffuse the Gaussian beam.

This paper presents studies on the impact of the erbium ions Er3+ on the properties of magneto - optical of the tellurite glasses Magneto-optical properties were investigated based on measurements of the Faraday effect and magnetic susceptibility as well as optical properties of the glasses, i.e. transmission in the visible range. The tests were carried out for clean glass matrices synthesized using various modifiers and glasses additionally doped with erbium ions Er3+. The aim of doped with ions of the paramagnetic element from the lanthanide group was to try to obtain higher Verdet constant values in the examined materials. The dominant type of magnetic ordering was determined on the basis of measurements of the permanent magnetic susceptibility using a vibration magnetometer. The obtained results indicate the paramagnetic nature of the magnetic order in the examined glasses. Glass doped with paramagnetic ions Er3+ resulted in the increase of their magnetic susceptibility, which suggests the possibility of observing better magneto-optical properties. The magneto-optical properties of tellurite glasses were determined based on measurements of the Faraday effect and calculation of the Verdet constant for different wavelengths of polarized light. The obtained results confirm the improvement of the magneto-optical properties of the examined glasses under the influence of doped with erbium ions. The obtained optical parameters are interesting from the point of view of the design of optoelectronic systems. The results of transmission tests showed high permeability of the examined tellurite glasses. The presented results may be important for the development of new materials based on tellurite glasses for applications in optoelectronic devices.

A systematic characterization of optical and chemical properties of fluorotellurite glasses based on 70TeO2-5 M x O y -10P2O5-10ZnO-5PbF2 glasses as function of alkaline earth metals as network modifiers were studied and analysed. The Z-scan results show that all the compounds have NLO properties such as nonlinear refractive index ( n 2 ) and two photon absorption ( β ). Finally, using ( n 2 ) and ( β ) we also determined the third-order nonlinear optical susceptibility χ 〈 3 〉 . It was found that the alkaline earth metals elements, have an influence on such NLO properties. Based on the ability of the lattice modifiers to decrease the band-gap energy while simultaneously increasing the linear refractive index of the TeO2-based glass, we investigated how these modifiers affect the non-linear refractive index.

This paper reports the second- and third- order nonlinear properties of Er3+/Yb3+ -doped PbO-GeO2-Ga2O3 glasses with Au nanoparticles. The glasses were prepared by the melt-quenching technique, followed by annealing for the nucleation of gold nanoparticles. A 200 kV high-resolution transmission electron microscope (HR-TEM) was used to verify the presence of Au nanoparticles and estimate their sizes. The role of annealing on the possible variation of the third-order nonlinear electric susceptibility is studied in details following the possible changes in the Au nanoparticle concentration. Two-photon absorption (TPA) coefficient (β) and nonlinear refractive index (n2) was measured by the conventional Z-scan method at 532 nm wavelength. The highest values were obtained for the sample with gold nanoparticles annealed for 52 h. Second harmonic generation (SHG) measurements were also performed and showed low conversion efficiency.

The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology. The quantum chemical calculations were performed for isolated monomers of lenses compounds as well as for their dimers and trimers to elucidate the effect of Omafilcon A polymerization and the role of an individual components.

A series of lithium niobate LiNbO3 (LN) single crystals doped with Er3+ were grown under the same conditions by melt-quenching method. The distribution coefficients of rare-earth (RE) elements in the ”crystal-melt” system of LN were determined at the beginning of the crystal growth. Their dependence on the dopant concentration in melt for 0.4 and 0.8 wt % was investigated. The procedure is applied to RE-doped lithium niobate (LiNbO3), a material of great interest for optoelectronic applications. We have obtained the real χ R ( 3 ) and imaginary parts χ I ( 3 ) of the third-order, nonlinear optical susceptibility to the nonlinear refractive index n2 and the nonlinear absorption coefficient β that are valid for absorbing systems. We show that nonlinear refractive or absorptive effects are the consequence of the interplay between the real and imaginary parts of the third-order susceptibilities of the materials. The method for measuring non-linear absorption coefficients and nonlinear refractive index based on well-known Z-scan is presented.

Studies of third-order nonlinear optical phenomena on Yb 3+ /Tm 3+ co-doped PbO-GeO 2 glasses containing different concentration of silicon nanoparticles are presented. The well-known melting-quenching technique was used for the production of the samples. Measurements were performed using conventional Z-scan, SHG and ESHG methods with Q-switched mode-locked ns scale Nd-YAG lasers, intensities in the 0.8–1.2 GW/cm 2 power density range and repetition rate of 10 Hz. Maximum third-order susceptibilities and second harmonic generation were found for the sample prepared with 1 wt% of Si powder.

Gold-nanoparticles (NPs) embedded in a germanate glass system were prepared and their linear and nonlinear optical properties were studied and analyzed. The glasses were produced using the melt-quenching technique and the NPs were synthesized using thermal reduction. Materials were prepared using 0.5 wt% of Er 2 O 3 and other concentrations (1.0/3.0 wt%) of Yb 2 O 3 and Au 2 O 3 . The data article reports the optical properties such as Urbach energy ( E U ), energy gap ( E g ) and linear refractive index ( n ). We showed that the linear refractive index for tested glasses is in the range 2.12 ÷ 2.33. Urbach energy and energy gap were determined using Tauc method. The result showed that E U are in the range 0.066 ÷ 0.150 [eV] and E g are 2.945 ÷ 3.006 [eV]. The nonlinear optical properties (NLO), such as nonlinear refractive index ( n 2 ), nonlinear absorption coefficient ( β ) and third-order nonlinear susceptibilities ( χ 3 > ), were also determined. Measurements were made using the Z -scan technique (wavelength λ = 532 nm, 1 Hz repetition rate). The magnitude of these parameters were found to be 1 0 − 6 cm 2 /GW, 1 0 − 9 cm/W and 1 0 − 20 m 2 /V 2 , respectively. The most increased TPA coefficient during the annealing process is observed in the material containing the largest amount of gold (PGG + 0.5%Er-1.0%Yb-3.0%Au). The annealing process is correlated with the reduction of gold ions and mainly influences the TPA results. The effect is stronger for samples containing higher quantities of gold.

Composites containing nanocrystallites of novel rare earth doped borate δ-BiB3O6 and polyvinyl alcohol (PVA) polymer are reported. Experimental studies of the third-order nonlinear refractive index n2, absorption coefficient β and second-order nonlinearity for δ-BiB3O6:Pr3+(7.5 at.%) large-size nanocrystallites embedded into PVA polymer matrices and deposited on gallium-doped zinc oxide substrates modified with silver nanoparticles (Ag-NPs) using Z-scan technique and second harmonic generation (SHG) method were performed. The complex SHG and Z-scan measurements for different sizes of Ag-NPs were done. It was shown that the polymer composite of PVA containing particles of orthorhombic bismuth triborate doped with praseodymium (7.5 at.%) reveals optically nonlinear response. It was shown that the studied composites possess both coherent and non-coherent component of nonlinear optics. The Z-scan measurements were done with use of 5 ns Nd:YAG laser and the second harmonic generation was measured using the 25 ns Nd:YAG laser with frequency repetition about 10 Hz. The measurements showed that both second as well as third-order susceptibilities are sensitive to the sizes of the Ag-NPs. The obtained results confirm a principal role of the Ag-NPs in influencing the output susceptibilities.

A study has been conducted in order to determine presence of free volume gaps in the structure of structure of polymer hydrogel contact lenses made in phosphoryl choline technology and of the degree of defect of its structure. The study was made by means of positron annihilation lifetime spectroscopy. As a result of the conducted measurements, curves were obtained, which described numbers of counts of the acts of annihilation in the time function. The conducted studies revealed existence of three components τ(1), τ(2) and τ(3). The τ(3) component is attributed to the pick-off annihilation of o-Ps orthopositronium trapping by free volume gaps and provides information about geometrical parameters of the volumes. At the same time, the UV-vis-NIR spectrometry examination was conducted on the same samples in the spectral range 200-1,000 nm.

The topography of indium tin oxide (ITO) films with incorporated silver nanoparticles and irradiated by single pulses of 18 ns Nd:YAG laser has been investigated. The study was carried out with two Ag/ITO films having resistances of 50 Ω and 4 Ω/square sheet resistances. The periodic structures in both samples were created after the laser treatment. The photo-induced periodic structures have a different character while the sheet resistance plays a major role in the growth process of these structures. The results of optical and non-linear optical investigations lead us to the conclusion that the temporary polarization of samples and high temperature of illuminated spot during laser treatment is responsible for the shape of periodic structures. This conclusion has been also confirmed by local permittivity measurements using evanescent microwave microscope and theoretical calculations concerning the temperature distributions during laser illumination.

We have found photoinduced second harmonic generation at wavelength 1064 nm during bicolor Nd:YAG laser coherent treatment of TeO2–ZnO and GeO2–PbO amorphous films. The maximally achieved second order susceptibility was equal to about 1.02 pm/V. Correlation of the induced second order susceptibility with local sample heating and induced birefringence may indicate an occurrence of local phase transitions from amorphous glass-like phase to non-centrosymmetry metastable phases.

The topography of indium tin oxide (ITO) films with incorporated silver nanoparticles and irradiated by single pulses of 18 ns Nd:YAG laser has been investigated. The study was carried out with two Ag/ITO films having resistances of 50 Ω/ITO sheet and 4 Ω/ITO sheet. The periodic structures in both samples were created after the laser treatment. The photo-induced periodic structures have a different character while the sheet resistance plays a major role in the growth process of these structures. The results of optical and non-linear optical investigations lead us to the conclusion that the temporary polarization of samples during laser treatment is responsible for the shape of periodic structures.

A principal role of the nanocrystallites of La2CaB10O19 on single pulse photoinduced changes of the liquid crystals was shown. It was established that the effect of the photoinduced changes is sensitive to the concentration of the nanocrystallites and to the type of liquid crystalline matrices. The principal role in the observed effects should play local thermoheating which determines effective exchange of energy between the nanocrystallites and the polymer matrices.

Measurements of three different stilbene derivative molecules incorporated into the PMMA and polycarbonate (PC) matrices using 10 ns Nd:YAG nanosecond laser λ = 1064 nm) as the fundamental ones were done. The chromophore molecules were incorporated into the corresponding matrices and aligned by the dc-electric field up to 4 kV/cm during the spin coating. We have established that the optimal content of the chromophore corresponded to the concentration of about 8.9% in weighting units. The samples had a thickness of about 0.5 mm. Theoretical quantum chemical simulations of the theoretical hyperpolarizability tensor β (SHG) and the magnitude polarizability tensor α for various excitation energies for the three modified stilbenes principally confirm the obtained results.

An efficient photoinduced method to operate by average sizes and heights of silver nanoparticles deposited on transparent and conductive substrates by seed-mediated growth method is proposed. The study is carried out with indium tin oxide (ITO) and fluorine doped tin oxide (FTO) substrates having 4 and 14 Ω/square sheet resistance, respectively. These two substrates determine different photoinduced aggregation of silver nanoparticles. The substrate resistance appears as the principal origin of the observed photoinduced aggregation features. The nanosecond kinetics of phototransparency engenders temporary oscillations in the range of nanosecond time. Several roles of the local overheating occurring through the electron–phonon interactions are evidenced.

A new promising organic chromophore for two-photon laser absorption at 1064 nm with 1,4-diethoxy-2,5-bis[2-(5-methylthien-2-yl)ethenyl]benzene (A-C) was synthesized. We have performed evaluations of the two-photon absorption for these chromophores incorporated into the polymer matrices. Following the obtained quantum chemical data, we have performed quantum chemical simulations of the third-order susceptibilities for the investigated chrompophore incorporated into the PMMA matrices. The calculations were done within the three-level model. We have established that the experimentally calculated data are a bit less than theoretically calculated; however, the general tendency of their changes shows a good coincidence. The maximally achieved value of the TPA is equal to about 59.2 cm/GW at wavelength 1064 nm, which, together with their high photothermal stabilities, make them good candidates for optical-limiting processes.

Electron beam induced second harmonic generation (SHG) is studied in Er3+ doped PbO–GeO2 glasses containing silver nanoparticles with concentrations that are controlled by the heat-treatment of the samples. The SHG is observed at T = 4.2 K using a p-polarized laser beam at 1064 nm. Enhancement of the SHG is observed in the samples that are submitted to electron beam incidence. The highest value of the nonlinear susceptibility, 2.08 pm/V, is achieved for the sample heat-treated during 72 h and submitted to an electron beam current of 15 nA. The samples that were not exposed to the electron beam present a susceptibility of ≈0.5 pm/V.

Photoinduced linear electrooptics effect (EOE) was discovered for three push-pull benzoxazole based stilbenes with different electron withdrawing and donating substituents at the phenylene and methane groups. The ground state geometry optimization for trans-stilbene has been performed using molecular mechanic geometry optimization within a framework of MM + force field method. We have done simulations of the optical absorption spectra and we have compared them with the experimental spectra. Quantum chemical simulations of UV-absorption spectra were done within a framework of semi-empirical restricted Hartree-Fock level (RHF) by AM1 (Austin Model 1) and PM3 (Parametric Method 3) methods. In addition, semi-empirical quantum mechanical calculations were carried out to verify reliability of theoretical simulations with respect to experimental data. Furthermore, semi-empirical quantum mechanical calculations indicated substantial difference of absorption obtained for the stilbenes possessing the in-plane and out-of-plane benzoate complexes. The maximally achieved value of photoinduced EOE coefficient was equal to 11.7 pm/V during illumination by λ = 1060 nm and λ = 530 nm coherent wavelengths. Correlation between the AFM morphological structure and EOE coefficients for the three investigated stilbenes was demonstrated.

We have studied thin nanolayers (with thicknesses of about 1–2 nm) between In2O3:Sn (indium–tin oxide (ITO)) crystalline films and glass substrates using the photo-induced optical second harmonic generation (PISHG) method. The maximal PISHG response observed for the pump–probe delay times was about 26 ps. The performed experimental measurements and quantum chemical theoretical simulations show that the observed effects are caused by two factors. The first is caused by the film–glass interface potential gradient and the second is a consequence of additional trapping levels appearing in the energy gap, particularly due to Sn doping. PISHG may be considered as a sensitive tool for such kinds of semiconductors.

We have found that the optical treatment by bicolor two laser beams at 1064 and 532 nm, at energy densities 80–120 mJ/cm2 originating from the same 10 ns Nd3+ garnett lasers causes the occurrence of the piezooptical effect in 50–80 nm γ-glicyne polymer nanocomposites at nanoparticle content about 6.5% in weighting unit. We propose to use this effect for optical triggers.

We have established a principal role of the polarity of polymer matrices on the piezooptical dispersion of the γ-glycine nanocrystallites embedded into the polymethymethacrylate (PMMA) and polycarbonate (PC) matrices. We found that the optical treatment by bicolor two laser beams at 1064 nm and 532 nm which are originating from the same 10 ns Nd:YAG laser, causes occurrence of the piezooptical effects. The optimal content of the γ-glycine nanocrystallites with respect to the magnitude of piezooptical coefficients was within the range of size 50–80 nm, corresponding to the 6.5 wt.%. We studied relaxation and spectral dependence of the corresponding coefficients of the piezooptic tensor.

An influence of the cw laser treatment at 660 nm (red), 532 nm (green) and 405 nm (blue) wavelengths on the absorption in l -alanine crystals was studied. We have established that increasing time of illumination for red laser wavelength leads to slight changes of absorption backgrounds without changes in the spectral features. The drastic changes are observed after illumination by green laser leading to occurrence of two clear and several less clear bands correlating well with increasing illumination time. Their intensities are only slightly dependent on time of optical treatment. The remaining part of the spectra demonstrates substantially less changes. Increasing optical SHG show clear correlation with the behavior of the red laser induced absorption. The effect demonstrates slow time decay.

We have observed a several times enhancement of the optical second harmonic generation in newly synthesized Europium doped PbO–Bi2O3–Ga2O3–BaO glasses for the fundamental wavelength 1320 nm during optical treatment by coherent fundamental and doubled frequency beams with a pulse duration about 15 ns. We have found that the maximal optical second harmonic generation was achieved for the Eu content of about 1.4% at fundamental beam average power equal to about 3 GW/cm2 , temperature of about 300 K and intensity ratio between the fundamental and doubled frequency beams of about 9. Frequency repetition of the optical pulses was equal to about 10 Hz. It was shown that doping by other rare earth ions, particularly by Dysprosium does not give a sufficient contribution to the effect.

RbNd(WO 4 ) 2 single crystals with different concentrations of Yb 3+ have been grown using the top seeded solution growth. Room-temperature absorption spectra were assigned on the basis of the Dieke's diagram for Nd 3+ ion and analyzed by means of the standard Judd–Ofelt theory. It was shown that the increase of the Yb 3+ concentration and corresponding decrease of the Nd 3+ concentration leads to the increase of the corresponding Judd–Ofelt intensity parameters, which suggests significant contribution of the Yb–Nd energy transfer in the formation of the absorption spectra.

The Z-scan measurements for the non-centrosymmetric optical crystals β-BaTeMo 2 O 9 (BTMO) were performed. The corresponding experiments were carried out using the 5 ns pulses of the second harmonic of a nanosecond Nd:YAG laser at the 532 nm wavelength. It was shown that the studied crystals possess promising third-order optical susceptibilities, which allow to use the crystal as optical limiters. The comparison with other oxide materials is presented. To clarify the origin of the observed effect, the electronic and optical properties of BTMO were calculated using the density functional theory (DFT)-based method. The performed calculations of the electronic and optical properties revealed certain peculiar features that can be suitable for the nonlinear optical applications. The relation between the observed nonlinear optical features and the calculated band structure is emphasized. The values of the calculated band gap and refractive index for β-BaTeMo 2 O 9 are also reported.

We have established an occurrence of modulated surface structures that are more marked on Ag than Au nanoparticles (NP) respectively deposited on indium tin oxide (ITO) substrates. It has been observed that the period of the structure features strongly depends on the resistivity of the substrate involved. AFM investigations showed that the structure period changes between 1.15 and 3.39 µm and substantially depends on the pulse frequency and the wavelength of the irradiation light. The origin of the phenomenon observed is given in the framework of the photo-thermal effects.

Absorption spectra and surface topography of optically modified silver nanoparticles grown on ITO thin layers are here investigated. The study is carried out with two ITO layers respectively having 50 Omega/square and 4 Omega/square sheet resistivity. The surface of the Ni samples are treated by one, three and five single pulses of 20 ns Nd:YAG laser. After the irradiation processes, the grating-like structures of various periods are observed. The result obtained is mainly assigned to the concentration of free electrons that is responsible for the surface plasmon resonance and the heat transfer phenomenon.

International audience; Palladium nanoparticles deposited on SnO2-doped In2O3 substrate show substantial optical second harmonic generation (SHG) in the spectral range (λ = 120–160 nm) which is a part of the vacuum ultraviolet (VUV) spectrum. A single crystalline Li2 B4 O7 optical parametric generator (OPG) pumped by nanosecond xenon–fluorine excimer laser (EMG 500/218 (Lambda Physics)) with the wavelength 218 nm, pulse duration about 6–8 ns; pulse rate about 80 hz, average pulse power about 0.2 MW and beam diameter varying within the 1.3–7.5 nm was used to form the fundamental beam. The OPG Li2 B4 O7 single crystal was cut in the XZ optical plane. We have tuned the fundamental wavelengths within the 250–320 nm spectral range varying the angle of the plane with respect to the incident pumping beam. Maximal SHG output (in the reflected SHG geometry) is observed for the incident angles 75○–80○ with respect to the surface normal and p-polarized incident fundamental ultraviolet beams. Spectral separation between the vacuum ultraviolet (VUV) SHG intensities and the fundamental beams was performed using a VUV Seya-Numioka vacuum monochromator with spectral resolution 6 nm in the investigated spectral range. We have found that decreasing mean average palladium nanoparticle sizes favour substantial enhancement of the output SHG within the 120–160 nm spectral range. A layer of platinum nanoparticles coated on a layer of palladium nanoparticles suppresses the SHG effect indicating a quenching of the surface plasmon excitation originating from the palladium nanoparticles. The observed effect allows utilizing the palladium nanoparticles as an efficient material for frequency transformation of the UV nanosecond pulses (spectral range 240–310 nm) into the nanosecond laser pulses with wavelengths 120–160 nm.

For the first time we have discovered drastic photoinduced effects in the transparency for the pyrrole films. Photoinduced investigations of transparency were performed for the polypyrroles with different number of the pyrrole rings. We have established a considerable increase of the transparency from 70–75% up to 82–84% for the wavelengths of the probing lasers operating within the 530–1040 nm spectral range. The photoexcitation was performed by nanosecond pulsed polarized Nd-YAG laser generating at 1.34 μm. The phototransparent changes are completely reversible and disappear after switching off the laser treatment. The typical relaxation time for the photoinduced transparency is equal to about 10–20 μs and the changes of the transparency are strictly related with the values of state dipole moments of the polypyrroles. As a possible mechanism for explanation of the observed dependences one can consider existence of the charged trapping levels intra the forbidden energy gaps which effectively interact with the electric strength of the external polarized optical field and state dipole moments of the particular polymers.

We have discovered a strong influence of the ZnO grain sizes on the output second harmonic generation stimulated by nanosecond pulses of 371 nm nitrogen laser during simultaneous superposition of the electrostatic electric field with electric strength about 2 kV/cm. To explore an influence of film morphology on the second order optical susceptibility we have explored the films prepared by electron sputtering with averaged grain sizes about 1000 nm and films synthesized by rf-magnetron sputtering on the two different substrates – glass and amorphous quartz with average grain sizes about 137 nm and 29 nm, respectively. Comparing the UV-induced optical second harmonic generation for the ZnO films with different grain sizes we have concluded that the samples with nanorods are characterized by considerably larger second order susceptibility (up to 5.7 pm/V at 1064 nm fundamental wavelength) compared to those for the films with smaller grain sizes (1.5 pm/V). This may be caused by a fact that UV-illumination deals only effectively with simultaneous electric field treatment enhancing the second order optical susceptibility. A correlation between the temperature of local laser thermo-heating and the output optical second harmonic generation may indicate on principal role of the local thermal expansion in the observed output second harmonic generation.

We have observed an appearance of clear morphological structure in composites containing In2O3 nanocrystals (NCs) incorporated into polymethyl methacrylite (PMMA) matrices under optical treatment by a polarized femtosecond laser. The initial photoinduced treatment was carried out using a Ti:sapphire femtosecond laser emitting 140 fs p-polarized light at a maximum spectral wavelength 775 nm with pulse repetition 1 kHz. It was found that the average morphological radius is varied maximally only during illumination at liquid helium temperature (T = 4.2 K). The morphological average mean radius is strictly dependent on the sizes of incorporated In2O3 NCs. Afterwards we measured the linear electrooptic effect at cw He–Ne laser wavelength 633 nm during simultaneous treatment by 1060 and 530 nm coherent beams of a Nd–YAG picosecond laser. We have established that a decrease of the average morphological mean radius favours an increase of the optically poled linear electrooptic coefficient. The diameters of In2O3 NCs were evaluated using transmission electron microscopy (TEM) and light-scattering techniques, whereas the NC sizes and morphological average mean radius of formed nanocomposites were estimated by atomic force microscopy (AFM). A relationship between the diameter of the NC, composite morphological mean average radius and effective linear electrooptic coefficient was established. (Some figures in this article are in colour only in the electronic version)