1,720,972 research outputs found
Chalcogenide glass thin films: Z-Scan measurements of refractive index changes
No full textNonlinear properties of chalcogenide glass As2S3 thin films have been measured with a self-diffraction (Z-Scan) technique. Photostructural changes and dynamical effects have been measured
Nonlinear Fabry-Perot cavity with chalcogenide glass thin films
No full textAn investigation of a chalcogenide glass thin‐film Fabry–Perot cavity has been performed in picosecond time regime. Nonlinear behavior of the structure derives from both nonlinear absorption of the material and changes in the resonance conditions of the cavity. The conditions to have bistable behavior have been established
On-off resonance femtosecond non-linear absorption of chalcogenide glassy films
No full textNon-linear absorption of chalcogenide thin films has been investigated with femtosecond pump-probe experiments. Different peculiarities of femtosecond pulse absorption have been found in the case of on- and off-resonance pumping and probing, due to either intraband or interband transitions. The physical mechanisms which can explain such different behaviours are discussed
Peculiarity of porous silicon formed in the transition regime
No full textElectrochemical anodization in the transition regime, between porous silicon formation region and electropolishing region, of monocrystalline silicon was investigated. Using this process bright and stable photoluminescence could be obtained on a very large range of substrate resistivities: p=12-0.005 Ωcm for p-type silicon and p = 20-0.001 Ωcm for n-type substrates.
Photoluminescence spectra, Fourier Transform IR (FTIR) absorbance and X-Ray Diffraction (XRD) measurements are reported. Investigations showed that anodic silicon suboxide was formed on the surface. The porous structure obtained in the transition regime is suggested to consist of silicon crystallites built inside an anodic oxide
Nonlinearity and photostructural changes in glassy As2S3 thin films
No full textMeasurements are reported of the refractive index and absorption coefficient changes of amorphous As2S3 (chalcogenide glass) thin films due to cw laser light irradiation. We have measured the transmittance through a thin film in the Z-scan technique configuration. Two different contributions to refractive index changes are demonstrated, showing the existence of a permanent and a dynamical effect. The first effect was demonstrated performing usual normal incidence transmittance measurements. The second dynamical change, revealed by the Z-scan technique, disappears once the light source is turned off: measured in the latter case is a maximum change of the refractive index Δn=-8×10-3 in the cw regime at λ=514.5 nm
Nonlinear propagation of nanosecond and picosecond light pulses in chalcogenide glasses
No full textN.D
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