Beata Derkowska

Third harmonic generation in undoped and X doped ZnO films (X: Ce, F, Er, Al, Sn) deposited by spray pyrolysis

There is a current interest in research of wide band gap semiconductor materials for the purposes of third order nonlinear optical properties in view of optoelectronics applications. Materials for nonlinear optics should present important changes of nonlinear intensity, dependence on changes of nonlinear refractive index, short response time, and weak absorption losses. We report the results of the third order nonlinear optical susceptibilities of undoped and doped (cerium, fluorine, erbium, aluminum, and tin) zinc oxide films using the third harmonic generation technique at 1064 nm wavelength region in picoseconds regime. Thin films were grown on glass substrate by the spray pyrolysis technique at different temperatures of substrates and characterized by using the x-ray diffraction, scanning electron microscope, transmission, and photoluminescence. A strong third harmonic signal was obtained from the studied films with a good crystallinity and roughness. We have found that at high conductivity, there is ...

Influence of different peripheral substituents on the nonlinear optical properties of cobalt phthalocyanine core

In this article, we show how the substituting different peripheral substituents around the cobalt phthalocyanine core correlate with nonlinear optical properties. We present the results on nonlinear optical properties of solution of cobalt phthalocyanine (CoPc), cobalt phthalocyanine with DNA-CTMA surfactant complex (CoPc-DNA-CTMA), and cobalt phthalocyanine with liquid crystal (CoPc-LC) measured by degenerate four-wave mixing (DFWM) method at the 532 nm wavelength region. We found that the values of third-order nonlinear optical susceptibility (χ⟨3⟩) of CoPc-LC and CoPc-DNA-CTMA increase in comparison with the value of the third-order nonlinear optical susceptibilities of CoPc. We supposed that this is caused by increase of the charge-transfer effects and of the dipole moments of the molecule with the increase of the chain length.

Stationary and modulated absorption spectroscopy of copper phthalocyanine (CuPc) layers grown on transparent substrate

Copper phthalocyanine thin films grown on glass and quartz substrates by the thermal evaporation method were investigated using stationary and modulated photoabsorption as well as photoreflectance spectroscopy. The stationary and modulated studies at room temperature were performed in the wavelength range 200–1200 nm and 400–1200 nm, respectively. The absorption coefficient of investigated layers was determined directly from the transmission spectrum and fitted in terms of the mixed Lorentz–Lorenz model, which assumed five oscillator components. Sensitive modulated spectroscopy, which enabled us to emphasize weakly visible transitions in the Q-band spectral region, was also performed to estimate the electronic structure of metallophthalocyanine layers. The complex nature of excited states of the metallophthalocyanine layers gave us abundant modulated spectra. These spectra were fitted using the third derivative line shape given by the Aspnes formula. Modulated photoabsorption and photoreflectance spectra for CuPc thin layers are presented for the first time in this paper.

Study of the third order nonlinear optical properties of Zn1−xMgxSe and Cd1−xMgxSe crystals

Third order nonlinear optical susceptibilities χ<3> of ternary Zn1−xMgxSe and Cd1−xMgxSe crystals have been measured using standard degenerate four-wave mixing (DFWM) method at 532 nm. The nonlinear transmission technique has been applied to check if our crystals exhibit two-photon absorption. The studied Zn1−xMgxSe and Cd1−xMgxSe solid solutions were grown from the melt by the modified high-pressure Bridgman method. For both crystals the energy gap increases with increasing Mg content.In the case of Zn1−xMgxSe, it was found that the value of third order nonlinear optical susceptibility χ<3> decreases with increasing Mg content. An explanation of this behaviour results from the dependence of optical nonlinearities on the energy band gap Eg of the studied crystals. In the case of Cd1txMgxSe with low content of Mg, no response was observed for the studied wavelength since the energy gap in such crystals is smaller than the photon energy of the used laser radiation.It was also found that the value of third order nonlinear optical susceptibility χ<3> for Cd0.70Mg0.30Se is higher than for Zn0.67Mg0.33Se. This behaviour can be understood if one take into consideration that the free carrier concentration in Cd1−xMgxSe samples is about four orders of magnitude higher than that in Zn1txMgxSe ones with comparable Mg content respectively. It is commonly known that when the electric conductivity increases, the values of nonlinear optical properties increase.From the performed measurements one can conclude that the incorporation of Mg as constituent into ZnSe and CdSe crystals leads to a change of the third order nonlinear optical susceptibilities.

New Methacrylic Oxazolone and Thiazolidinone Containing Polymers for Nonlinear OpticalApplications

Oxazalone and thiazolidinone derivatives were synthesized and their physicochemical properties are determined by absorption, HNMR spectroscopies. The third order nonlinear optical properties of oxazolone and thiazolidinone containing compounds were investigated in solutions using degenerate four wave mixing (DFWM) method at 532 nm.

Dependence of the Third Order Nonlinear Optical Susceptibility on Concentration and Peripheral Substituent of Metallophthalocyanines

Third order nonlinear optical properties of metallophthalocyanines (MPcs) were investigated using degenerate four wave mixing (DFWM) method. We also studied how the replacement of peripheral substituent around the MPcs cores correlates with nonlinear optical properties. Therefore third order nonlinear optical susceptibilities (χ<3>) of MPcs with liquid crystal (MPcs-LC) were investigated. We found that the χ<3> values of MPcs-LC increase in comparison with the corresponding values of MPcs. We supposed that this is caused by the increase of the charge transfer effects and change of the dipole moments of the molecule with the increase of molecules dimension.

Third-order nonlinear optical properties of CuPc: influence of thickness and concentration

The concentration dependence of third order nonlinear optical susceptibility ( χ<3> ) of copper phthalocyanine (CuPc) dissolved in tetrahydrofuran (THF) using the degenerate four wave mixing (DFWM) method at 532 nm was investigated. We present the linear dependence of the third order nonlinear optical susceptibility ( χ<3> ) as a function of different concentration for CuPc dissolved in THF. We also calculated the second order hyperpolarizability ( γ) of CuPc solutions. Third harmonic generation (THG) measurements at the 1064 nm performed on CuPc thin films are also presented. We found that the χ<3>DFWM values are larger than the χ<3>THG ones. This variation observed in χ<3> values, occurs probably due to the different resonance contributions in solution and solid state of CuPc. We show that in the case of DFWM measurements the one and two-photon resonant contributions at the Q and C-band increase χ<3>DFWM value of CuPc. In THG measurements, the three-photon resonance contribution at the Soret band gives rise to higher χ<3>THG value.

Grown of ZnO:Ce layers by spray pyrolysis method for nonlinear optical studies

We have investigated the linear and nonlinear optical properties of high quality cerium-doped zinc oxide films (ZnO:Ce). The layers were grown by the reactive chemical pulverization spray pyrolysis technique using zinc and cerium chlorides as precursors at temperature up to 450/spl deg/C. The influence of Ce concentration on the structural, linear and nonlinear optical properties of ZnO thin films is presented. The films were characterized by X-ray diffraction, scanning electron microscope and photoluminescence measurements. The X-ray diffraction analysis indicates that all films are polycrystalline in nature and clearly shows the appropriate incorporation of the Ce atoms in the ZnO films. The third order nonlinear optical properties, which are the main subject of this investigation, were studied. For this propose, the third harmonic degeneration (THG) technique has been employed. A laser source has been used for the fundamental beam at 1064 nm so that the generated third harmonic signal is made at 355 nm.

Dependence of nonlinear refractive index of ZnSe on Be and Mg content

The values of the nonlinear refractive index n2 and the two-photon absorption coefficient β of ternary and quaternary ZnSe-based mixed crystals were extracted from the standard backward degenerate four wave mixing (DFWM) and nonlinear transmission measurements at 532 nm, respectively. Studied crystals were grown by the modified high-pressure Bridgman method. We found that the value of the nonlinear refractive index n2 for Zn0.79Be0.21Se is higher than that for Zn0.80Mg0.20Se. However, the opposite behaviour was found in the case of two-photon absorption coefficient β for these compounds. We also found that the values of the nonlinear refractive index n2 and the two-photon absorption coefficient β for Zn0.83Be0.04Mg0.13Se are about five times lower and three times higher than that for Zn0.80Mg0.13Se, respectively. In the case of ternary ZnSe-based crystals we noticed that the value of the nonlinear refractive index n2 decreases with increasing Mg or Be content. However, the value of the two-photon absorption coefficient β increases with increasing Mg or Be content.

Experimental results of third order nonlinear optical susceptibility of oriented and annealed ZnSe crystals

The values of third order nonlinear optical susceptibility (χ‹3›) of ZnSe oriented [100] as well as oriented [111] and then annealed in the zinc air crystals were extracted from the standard backward degenerate four wave mixing (DFWM) and nonlinear transmission measurement at 532 nm. The studied crystals were grown by the modified high-pressure Bridgman method. We found that higher value of third order nonlinear optical susceptibility (χ‹3›) was obtained for oriented [100] ZnSe crystal and lower one for ZnSe oriented [111] and then annealed in the zinc air. To our knowledge the DFWM measurements were made for the first time in this kind of materials.