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

Derkowska B., Firszt F., Marasek A., Sahraoui B.

Opto-Electronics Review

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2010

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Vol. 18, No. 4

384-387

EN

The values of the nonlinear refractive index n₂ and the two-photon absorption coefficient ß 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 ß for these compounds. We also found that the values of the nonlinear refractive index n2 and the two-photon absorption coefficient ß 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 ß increases with increasing Mg or Be content.

2

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

Derkowska B., Firszt F., Sahraoui B., Marasek A., Kujawa M.

Opto-Electronics Review

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2008

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Vol. 16, No. 1

8-11

EN

Third order nonlinear optical susceptibilities χ³ 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 χ³ 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 Cd₁₋xMgxSe 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 χ³ for Cd₀.₇₀Mg₀.₃₃ 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 Zn₁₋x MgxSe 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.

3

Second harmonic generation in Ru-derivative chromophores incorporated within PMMA polymers stimulated by acoustic and optic fields

Migalska-Zalas A., Kityk I. V., Sahraoui B.

Opto-Electronics Review

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2005

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Vol. 13, No. 2

141-145

EN

We have demonstrated the co-existences of second harmonic generation (SHG) and χ (2) grating using acoustical and optical fields in Ru derivatives incorporated within the PMMA polymer matrices. The investigated compounds possess metastable trapping levels originated both from the d-states of Ru as well as the effective charge transfers due to the presence of p-conjugated states. The investigated compounds possess long-lived χ (2) grating which decreases less than 76% under 600 min of laser treatment. Electrostatic field causes additional reanimation of the SHG. Values of the acoustically induced optical second harmonic generation (AIOSHG) for the best Ru chromophres were substantially higher than for known pure inorganic materials. The effective value of the second-order optical susceptibility for the wavelength 1.89 um is about 1.94 pm/V. With increasing acoustical power, the AIOSHG for fundamental YAB-Gd laser light (λ = 1.76 um) increases and achieves its maximum value at acoustical power density of about 1.45 W/cm2.

4

Linear and nonlinear optical properties of Zn 1-xMgxSe layers grown by MBE and PLD methods

Derkowska B., Wojdyła M., Płóciennik P., Sahraoui B., Bała W.

Opto-Electronics Review

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2004

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Vol. 12, No. 4

405-409

EN

Ternary and quaternary AII BVI mixing semiconductors are very attractive materials for various optical devices. Their optical properties such as the energy gap, linear refractive index, absorption coefficient and lattice constant can be changed with increasing component. For the practical application linear and nonlinear optical characterizations such as the two-photon absorption (TPA), linear and nonlinear refractive indexes are an important aspect. A practical motivation to measure the magnitude of TPA coefficient is that the performance of a device based on nonlinear refraction is strongly affected by the eventual nonlinear absorption. The refractive index and TPA coefficient of Zn1-xMgxSe compounds grown on glass substrates by molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) methods were systematically investigated as a function of Mg composition. The linear optical properties have been studied using transmission, reflection, and photoreflection spectroscopy. The nonlinear optical properties of these materials were investigated by the nonlinear transmission. The energy gap and linear refractive index of these materials change with Mg content, hence the nonlinear optical processes such as TPA and nonlinear refraction index can be modified.

5

The IR photoinduced changes in the Y-Ba-Cu-O thin films

Sahraoui B., Derkowska B., Kryza A., Kityk I.V.

Optica Applicata

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2001

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Vol. 31, nr 2

445-451

EN

The Y-Ba-Cu-O thin films are promising materials because they have not only superconducting properties but also good optical properties, particularly in the IR spectral range. We investigate the photoinduced optical changes in the IR region for oriented Y-Ba-Cu-O thin films deposited on [left angle bracket]110[right angle bracket] surface of ZnSe single crystals, using differential IR spectroscopy Fourier technique in the spectral region between 100 cm/sup -1/ and 450 cm/sup -1/. We have also found the photoinduced photodarkening effect under the influence of the CO/sub 2/ pulse laser ( lambda =10.6 mu m). The possibility of using the above-mentioned materials as promising materials for IR optoelectronics and nonlinear optics is discussed.