Photoluminescence and attenuation of spray-pyrolysis-deposited erbium-doped Y2O3 planar optical waveguides

Erbium-doped Y20 3 planar optical waveguides have been fabricated by spray-pyrolysis deposition. The attenuation spectrum of the waveguide shows peaks that are due to absorption of the erbium ions. The as-deposited layers also show photoluminescence sharply peaking at 1540 nm with additional Stark splitting. The thin layers of Er 3:Y 203 obtained are promising for the realization of integrated-optic amplifiers and lasers

Domain studies of CoCr with perpendicular anisotropy

R.F. Magnetron sputtered CoCr films (79/21 at%) with various thicknesses are magnetically characterized. The domain structure is observed by digitally enhanced Kerr microscopy and depends on the Hc/Hk values of the samples. For low and high coercivity films a comparison is made between the measured VSM hysteresis, domain period and a theoretical domain model. The domain shape is a function of the magnetic history of the sample and the bending created by the deposition process

R.F. planar magnetron sputtered ZnO films I: structural properties

The structural properties of r.f. planar magnetron sputtered ZnO films are studied as a function of deposition parameters: substrate type, substrate temperature, sputter gas pressure, growth rate and sputtering power.\ud \ud These films are applied as piezoelectric transducers in micromechanical sensors and actuators. The electric properties, and consequently the piezoelectric behaviour, depend strongly on the structural properties of the layers.\ud \ud All films are polycrystalline. The individual grains are highly oriented with their crystallographic c axis perpendicular to the substrate. Crystalline substrates such as silicon or SiO2 induce a growth of small grains, a few hundredths of a micron wide and long. Amorphous substrates such as metals or amorphous SiO2 induce a growth of broad columnar grains extending through the film thickness and a few tenths of a micron wide. Trends in density and grain size are in agreement with Thornton's structure zone model

Intrinsic angular investigations on metal evaporated tapes

Demagnetisation compensated torque- and angle-dependent remanence measurements are presented on commercial and experimental metal evaporated tapes. The latter have been prepared in our laboratory on a mini-roll coater system. From these results the easy axes have been determined

Simple technique for two-photon absorption measurements in polymeric waveguide channels

A simple technique for two-photon absorption measurements by pulse shape deformation in channel optical waveguides is described. Measurements on a ps time scale are performed. Results are in good agreement with literature value

Investigation on Co-Cr micro-strips for VBLM

Hard magnetic strips can be used for bit stabilization in a VBLM. For this stabilization the magnetic strayfield of the strips induce potential wells for the bits. However, by dimensioning a material into strips the magnetic properties and therefore the potential wells change. In this paper the relation between magnetic properties and shape of Co-Cr micro-strips is investigated. Furthermore the influence of both magnetic properties and shape of the strips on the magnetic strayfield is simulated

R.F. planar magnetron sputtered ZnO films II: Electrical properties

The electrical properties of r.f. planar magnetron sputtered ZnO films are studied by means of current-voltage, capacitance-voltage and Van der Pauw measurements.\ud \ud These films are applied as piezoelectric transducers in micromechanical sensors and actuators. Their piezoelectric behaviour strongly depends on the electric properties.\ud \ud A conduction model for the polycrystalline ZnO layers is presented. This model gives a good description of the electrical behaviour, and is useful in understanding the piezoelectric properties of the films studied

Characterization of optical third-order non-linearities by prism coupling and pulse shape analysis on a ps timescale

Materials with an intensity dependent index of refraction and absorption coefficient¿third-order optical non-linear (ONL) effects¿offer the possibility of all-optical signal processing. Prism coupling is a well-known tool to investigate the intensity dependent refractive index, however, such experiments are often obscured by thermal effects. To avoid these we have studied the influence of the ONL effects on the shape of 70 ps pulses in non-linear prism coupling. The full width at half maximum (FWHM) of the in and out coupled pulses is compared simultaneously with the FWHM of the pulses of a reference beam. By measuring at various angles of incidence around that for optimal coupling it is possible to measure the sign and value of the change in both the refractive index and absorption coefficient. As a function of the coupling angle, the first leads to an asymmetric line shape for the ratio of the two FWHMs mentioned above, whereas the second leads to a symmetric one. From a comparison of simulations with experimental data, the values of the non-linear constants can be derived

Granular YBaCuO films prepared by metalorganic chemical aerosol deposition technology

Fine-grain thin superconducting films can be prepared by metalorganic Chemical Aerosol Deposition Technology (CADT). In this paper, we present the preparation and properties of YBa2Cu3O7-x films on the different substrates, Si and SrTiO3 (100). It is shown that the zero-resistance temperature (Tc,0) of the films on SrTiO3 substrates is about 90 K, and the critical current density (Jc) at 77 K is above 104 A/cm2. In addition, these films exhibit significant grain-boundary weak link behaviour, which is very promising for applications in electronic devices