Large Amplitude Photocurrent In Photo-emf Experiments In Pure And Doped Absorbing Photorefractive Crystals

We report a mathematical formulation that successfully describes the holographic photocurrent produced in photo-emf experiments, with large oscillation amplitudes, in strongly absorbing photorefractive materials. The large amplitude produces a sensible enhancement of the photocurrent signal and in this way facilitates measurements. Accounting for bulk light absorption of the sample is essential in order to adequately describe the experiment. We measure pure and doped photorefractive Bi12TiO20 (BTO) crystals and show that these data are in excellent agreemnt with theory. From data fitting we are able to determine some material's parameters.4829 II953954Trofimov, G.S., Stepanov, S.I., (1986) Sov. Phys. Solid State, 28, pp. 1559-1562Petrov, M.P., Sokolov, I.A., Stepanov, S.I., Trofimov, G.S., (1990) J. Appl. Phys., 68, pp. 2216-2225Bittner, R., Meerholz, K., Stepanov, S., (1999) Appl. Phys. Lett., 74, pp. 3723-3725Korneev, N.A., Stepanov, S., (1993) J. Appl. Phys., 74, pp. 2736-2741Bryushinin, M.A., Dubrovsky, G.B., Sokolov, L.A., (1999) Appl. Phys. B, 68, pp. 871-87

Fringe-locked Running Hologram And Multiple Photoactive Species In Bi 12tio20

Fringe-locking techniques ar used for the recording of stable 90 °phase-shifted running holograms in photorefractive crystals. The use of this technique permits the characterization of a fast and a slow photoactive species in Bi12TiO20. We compare our results with those obtained from other methods and discuss the practical interest of this technique.6873104310

ANALYSIS OF A PHASE-MODULATING RECORDING MECHANISM IN NEGATIVE PHOTORESIST

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Enhanced photocurrent in photo-emf experiments in pure and doped absorbing photorefractive crystals

We report a mathematical formulation that successfully describes the holographic photocurrent that is produced, in strongly absorbing photorefractive materials, by the action of a pattern of interference fringes of light vibrating sinusoidally with large amplitude. The large vibrating amplitude produces a sensible enhancement of the photocurrent signal and in this way facilitates measurements. We also show that taking account of the bulk light absorption of the sample is essential for adequately describing the experiment. We measure the first temporal harmonic of the photocurrent, without an externally applied field, as a function of the amplitude and the temporal frequency of the vibrating pattern of fringes and show that these data fit our theoretical model well. From this fit we are able to determine some material parameters for pure and doped photorefractive Bi12TiO20 crystals. (C) 2002 Optical Society of America.19122904291

PHOTOREFRACTIVE RESPONSE-TIME MEASUREMENT IN GAAS CRYSTALS BY PHASE MODULATION IN 2-WAVE MIXING

We describe a new method for photorefractive response time measurement in fast photorefractive crystals based on continuous phase modulation in two-wave mixing. We report experimental results for undoped semiinsulating GaAs that are in good agreement with theory. Values obtained for the response time and photoelectron generation quantum efficiency are consistent with previously published data.19211702170

ADJUSTABLE PHASE-CONTROL IN STABILIZED INTERFEROMETRY

We report an optoelectronic feedback loop that permits the active stabilization of an interferometric setup for any chosen Value of the phase between the interfering beams. This method is based on phase modulation and homodyne detection techniques. The phase can be stabilized with a precision of better than 1 deg for our experimental conditions.20663563

Ronchi-grating-based measurement of photorefractive recording response time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We report on a simple technique for the measurement of the recording response time in photorefractive materials. Three different material samples were successfully measured, and their response times, as well as their dependence upon the recording/measurement light irradiance, were also determined and compared with available data in the literature in order to assess the reliability of this technique. (C) 2012 Optical Society of America372277279Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundo de Apoio ao Ensino, Pesquisa e Extensao (FUNCAMP-FAEPEX-PAPDIC), BrazilConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Photoinduced Schottky Barrier in Photorefractive Materials

We report on the first experimental evidence of a Schottky barrier effect produced by the action of light in an otherwise purely Ohmic contact between a nominally undoped photorefractive titanosillenite Bi(12)TiO(20) crystal and a transparent conductive SnO(2) electrode. The photorefractive crystal is sandwiched between two transparent electrodes and a Schottky barrier is built up in the illuminated crystal-electrode interface under the action of light with photonic energy large enough to excite charge carriers from the Fermi level into the conduction band. The contact remains purely Ohmic under illumination with photonic energy below that of the Fermi gap and the photoinduced barrier almost disappears if the photonic energy is large enough to produce electron-hole pairs.1041