Abstract
We report the experimental evaluation of the intensity-dependent index of refraction of a new class of third order nonlinear materials, side chain polymers containing 4-dialkylamino-4'-nitro-stilbene and 4-dialkylamino-4'-nitro-diphenylbutadiene as side groups. The measurements, based on nonlinear grating coupling into planar waveguides with 30 ps pulses at 1.064-mu-m, showed large electronic nonresonant n2 Kerr coefficients.

Abstract
The growth dynamics of UV induced IR absorption and related refractive index change in hydrogen loaded GeO2-doped fibers have been studied. We report a higher initial rate and strong saturation for Ge-OH generation compared with Si-OH formation under UV exposure. A close correlation was found between the Ge/Si-OH groups concentration and the induced index change as a function of the UV exposure time. (C) 1998 American Institute of Physics.

Abstract

Abstract
The bottom electrode crystallization method was used for the heat-treatment of amorphous Pb(Zr-0(52)., Ti-0.48)O-3 thin films deposited by radio-frequency magnetron sputtering on Pt/Ti/SiO2/Si substrates. Two different heating and cooling rates were applied and two different contact wires (W and Pt) were alternately used for the Joule heat generation in the Pt bottom electrode. The dielectric and ferroelectric properties of the films were compared with the properties of the films crystallized using halogen lamp annealing in the same conditions. All the PZT samples showed similar ferroelectric properties at room temperature, with high dielectric constant and remanent polarization values as well as good resistance to ferroelectric fatigue, the Al/PZT/Pt/Ti/SiO2/Si capacitors having low leakage currents. The experimental results obtained show that the bottom electrode crystallization method is a cheap and low power consumption method which can successfully replace the classical crystallization methods.

Abstract
A simple method for crystallizing amorphous thin films was developed using platinum bottom electrodes as heating elements. A current was applied to tungsten wires in contact with the platinum and the temperature was measured using a type-K thermocouple. A proportional feedback algorithm was used for controlling the process. The performance of different platinum electrodes was studied. Pt films with different thicknesses were alternatively deposited over Ti and Zr at 700degreesC. Applying currents up to 2 A to the Pt films, the resistance dependence of temperature was studied. The maximum temperature, 675degreesC, was obtained when using 200 nm Pt films deposited at 700degreesC over Ti, with a power consumption of 16 W. The method was applied to the crystallization of PbZr0.52Ti0.48O3 thin films using Pt films deposited at 500degreesC over Ti and at 700degreesC over Zr. The results obtained for heat treatments at 650degreesC with 10degreesC/s heating and cooling rates showed a pure perovskite phase; the ferroelectric properties were comparable with those from films crystallized by rapid thermal annealing. (C) 2004 American Institute of Physics.

Abstract
Third-order nonlinear and linear optical properties of nickel(II) and copper(II) complexes with salen ligands, functionalised with electron donor/acceptor groups (DA-salen), have been investigated in solution by the Z-scan technique using an Nd:YAG laser (lambda(inc) = 1064 nm) and UV/Vis spectroscopy. The [M(DA-salen)] complexes exhibit positive nonresonant nonlinear refractive indexes (net) in the range 27.0-8.50 center dot 10(-21) m(2)W(-1) and nonlinear absorption coefficients (a(2)(I)) within the range 1.80-26.0 center dot 10(-17) mW(-1). The latter values correspond to less than 10% of the overall magnitude of the third-order susceptibility, vertical bar chi(3)vertical bar, which is the result of the absence of electronic transitions near lambda(inc) = 1064 nm. For the group of N-II complexes, the highest net values are exhibited by the complexes with aromatic diimine bridges and large pi-electron delocalisation, which leads to intense electronic charge-transfer bands (epsilon > 16000 mol(-1) dm(3) cm(-1)) in the region lambda = 275-500 nm. The complexes that exhibit charge-transfer bands near lambda(inc)/2 = 532 nm, also show the highest a(2)(I) values, a consequence of multiphoton absorption processes. For the group of Cult complexes, the highest net value is also observed by the complex that exhibits the most intense charge-transfer bands in the region lambda = 275-475 nm. Between Ni-II and Cu-II complexes with the same DA-salen ligands, those of copper show always higher net values, indicating that NLO responses can also be fine-tuned by the metal centre. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)