1,721,117 research outputs found
Electrical and optical characterization of a Zn-implanted InP laser annealed in a nitrogen atmosphere
No full textSemi-insulating InP samples have been implanted with Zn in order to obtain p-type films. The implanted samples have been annealed by low-power pulsed-laser annealing in a N2 controlled atmosphere and in a vacuum. The Hall resistance measurements show that remarkable conductivity is obtained only in the case where the annealing is performed in a N2 atmosphere. The measured carrier activation energy evidences that the conduction is indeed due to the ionization of the implanted Zn atoms. Moreover, the mobility temperature behaviour has been used to evidence the carrier scattering mechanisms in the implanted and annealed layer. Lastly, the optical absorption coefficient of these samples has been measured by means of the photo-thermal deflection absorption technique in order to evidence the modification on the optical properties induced by the ion beam and laser irradiation
Lo studio delle proprieta' ottiche e termiche di materiali solidi con techniche laser
No full textDottorato di ricerca in elettromagnetismo applicato e scienze elettrofisiche. 7. cicloConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
A beam distorsion technique applied to the measurement of nonlinearities in CdSxSe1-x doped glasses
No full textRecently a single beam technique for measuring both the non-linear refractive index and non-linear absorption of transparent materials has been proposed by Sheik-Bahae et al. IEEE J. Quantum Electron., vol.26, p.760, 1990; in which the transmittance of a sample is measured through a finite aperture in the far field as the sample is moved along the propagation path of a focused Gaussian beam. The sign and magnitude of the non-linear refractive index and the value of absorption changes can be deduced from the transmittance curve. In the present paper this technique has been applied to evaluate both the thermal and electronic non-linear changes of refractive index and of absorption of some Schott semiconductor doped glasses by using the CW and pulsed regime
Reply to "Comments on 'The photothermal method applied to low thermal diffusivity measurements'"[Rev Sci. Instrum 66, 275 (1995)]
No full textExperimental evidence of the effect of nonlinear Fabry-Perot resonator response on Z-Scan measurements
No full textWe report experimental results of Z-scan investigations on the photoinduced nonlinear absorption and refractive index of submillimeter bulk samples of the III–V semiconductor InSb. The measurements were carried out in the cw regime at λ = 10.6 μm using a CO2 laser. The results put into evidence the contribution of the nonlinear Fabry-Pérot resonator, constituted by the high-refractive-index sample itself, to the transmittance of the system. Such contribution can lead to a wrong evaluation of the nonlinear optical coefficents in Z-scan experiments. The experimental data were fitted using a modified Z-scan theory in which the effect of the resonator is taken into account. The values for the nonlinear absorption and refractive index used in the fit are in good agreement with those reported in literature
Long-wave infrared emissivity characterization of vanadium dioxide-based multilayer structure on silicon substrate by temperature-dependent radiometric measurements
No full textThis paper studies the IR properties of a VO2-based multilayer structure with an emittance that increase with the temperature. A good tunability of the emissivity in long-wave infrared spectral region (8–12 μm) has been detected, with a positive emissivity differential of about 0.2. The transition of the long wave emissivity ε with the temperature is fully reversible according to a hysteresis cycle, with a transition temperature of 67 °C and a thermal bandwidth of only 8 °C. The multilayer structure also shows two emission peaks both in the heating cycle and in the cooling cycle. This emittance performance is promising for the future development of passive thermal control systems of spacecrafts
Analysis of defects in multilayers through photothermal deflection technique
No full textProduction and Testing of Optical Components and System
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