Experimental effects of light intensity modulation on the recording and erasure of holographic gratins in BSO crystals

Alvarez-Bravo, J.V.; Carrascosa, M.; Arizméndi, L.

doi:10.1016/0030-4018(93)90636-j

Cited by 19 publications

(6 citation statements)

References 22 publications

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“…The theoretical interest in justifying the E 1 alinearity is based on experimental results on the nonlinear m dependence for several materials. 7,8 Nevertheless, from the dependence law ͑16͒ we assure that these experimental results cannot be explained by this early Kukhtarev model. We believe that the validity of those results could rely on additional processes that take place in the material, for instance others active impurities or bipolar transport.…”

Section: Harmonic Gratings Dependence On Modulation Depthmentioning

confidence: 58%

“…However, if one likes to obtain highest index changes, then the modulation depth m must be increased and diffraction by harmonic gratings would appear. [6][7][8] Each harmonic grating represents a sinusoidal independent diffraction grating of spatial frequency K, K being the grating vector of the excitation pattern. The amplitude of each harmonic component that synthesize the spacecharge field is related with each -harmonic diffraction grating.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the steady-state photorefractive harmonic gratings

1999

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The steady-state exact solution for the higher harmonic gratings that synthesize the space-charge field are derived without restrictions within the Kukhtarev model. This allows us to know exactly the behavior of the harmonic amplitudes in terms of main parameters and the space-charge field spatial distribution. The amplitudes of the several gratings were found not to depend on the mean intensity of the fringe pattern in a typical cw range. With respect to the modulation depth m, the dependence of each -order harmonic amplitude is rigorously established as m . Also, regions of quite different behavior in terms of the grating spacing are identified and analyzed. From this analysis, it is emphasized that the higher gratings tend to appear more strongly for materials with smallest ratio of donors traps, and for increasing values of both modulation depth, and spacing grating. Also, the higher gratings behavior in terms of applied field is analyzed. The relative importance of high harmonics is more evident for smallest values of the external field.

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Section: Harmonic Gratings Dependence On Modulation Depthmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Analysis of the steady-state photorefractive harmonic gratings

1999

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“…, where is the wavelength employed and is the angle between the incident wave vectors. The 1-D distribution intensity is (1) where and are the incident beam intensities, is the modulation depth, and is the spatial variable.…”

Section: Electron-hole Transport Modelmentioning

confidence: 99%

“…T HE STUDY of nonlinear effects in photorefractive materials is of great interest because of its potential applications in optical and optoelectronic devices. Experimentally, it is well established that the nonlinearity appears at large modulation depths of the excitation intensity [1] and the nonlinear phenomena are related to the loss of the sinusoidal profile of the refraction index grating, which was attributed to the formation of harmonic gratings in addition to the fundamental grating [2]. Each harmonic grating satisfies the Bragg condition for its fringe spacing and has been observed in several photorefractive materials, such as barium titanate (BaTiO ) [3], [4], strontium barium niobate (SBN), barium strontium potassium sodium niobate (BSKNN) [3], bismuth oxide titanium (BTO) [5], and bismuth oxide silicon (BSO) [1], [6], [7].…”

Section: Introductionmentioning

confidence: 99%

An electron-hole transport model for the analysis of the photorefractive harmonic gratings

Vaveliuk

Ruiz²,

Matos³

et al. 2001

IEEE J. Quantum Electron.

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The steady-state exact solution for the higher harmonic gratings that synthesize the space-charge field is derived without restrictions within an electron-hole transport model which allows the behavior of these harmonic gratings to be determined rigorously in terms of the main photorefractive parameters. The model predicts the independence of the fundamental and harmonic amplitudes on the average excitation intensity. With respect to the modulation depth , the dependence of each -harmonic order is established as which is the result obtained in the single-level model. In terms of the grating spacing, three regions of quite different behavior are identified as the linear, transition, and nonlinear regions. The extent of each region in terms of 3 strongly depends on the acceptor density relative to the donor density. If the acceptor density is much greater or smaller than the donor density, the linear region spreads out toward the lowest spacing, the nonlinear region extends toward the highest spacing, and the intermediate region is located in-between, as in the Kukhtarev model. But, for similar concentrations, the nonlinear region is shifted toward smaller spacing with respect to the linear region. On the other hand, the electron-hole competition can be deleterious for recording the grating, due to the charge compensation produced by the additional charge carrier that screens the internal space-charge field. Also, the relative importance of the higher harmonics is apparent for the smallest values of the external field as in the single-level model.

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“…Por otro lado, también se observó difracción en redes de indice armónicas, en condi ciones experimentales que producen elevados valores en el factor de modulación. Las redes armónicas fueron observadas en diversos materiales fotorrefractivos como titanato de bario (BaTiOa) (15), (16) niobato de bario y estroncio (SBN) (15), niobato de bario, estroncio, pota sio y sodio (BSKNN) (15), óxido de bismuto y titanio (BTO)(17) y óxido de bismuto y silicio (BSO) (18), (19), (20). Cada una de las u-ésimas redes armónicas fotorrefractivas representa una red de difracción sinusoidal de frecuencia espacial v K con v E N y siendo K la frecuen cia espacial de la red fundamental, tal que cada v-ésima red armónica difracta un haz de lectura en ángulo de incidencia que satisface la condición de Bragg para su periodo espacial.…”

Section: Antecedentes Y Objetivosunclassified

Redes fotorrefractivas armónicas en el marco del modelo Kukhtarev y sus extensiones

Vaveliuk¹

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El conocimiento del régimen no lineal, donde se generan las redes fotorrefractivas armónicas está prácticamente limitado a un conocimiento aproximado del modelo de Kukhtarev. A esto se agrega la inexistencia casi total de un análisis teórico del régimen no lineal para materiales en los cuales existen trampas superficiales eficientes, ó un mecanismo de transporte electrón-hueco. Por lo tanto, dicho desconocimiento limita el análisis de las redes fotorrefractivas armónicas a situaciones casi ideales: un reducido número de materiales fotorrefractivos que no presentan procesos dinámicos adicionales a los postulados por el modelo de Kukhtarev y bajo condiciones de excitación muy restrictivas que no tienen en cuenta el régimen no lineal. Estas limitaciones nos han motivado a investigar el comportamiento teórico de las redes fotorrefractivas armónicas estacionarias en un marco global, es decir, resolviendo en forma exacta y sin simplificaciones las ecuaciones materiales dentro del modelo de Kukhtarev y las mencionadas extensiones: el modelo de trampas superficiales y el modelo de trasporte bipolar de carga, en un rango muy amplio de variación de los parámetros experimentales que incluye el régimen no lineal. Ello permite analizar las redes armónicas en términos de la intensidad media de excitación, la profundidad de modulación, el espaciado de red y el campo eléctrico aplicado. También, a partir del riguroso conocimiento de las amplitudes y fases de las redes fotorrefractivas armónicas, es posible obtener la precisa distribución del campo espacial de carga dentro del cristal en conjunción con la cantidad de componentes armónicas necesarias para su convergencia. Todo ello permite identificar las diferentes regiones de comportamiento lineal y no lineal. Todos los resultados han sido comparados para los modelos dinámicos aquí estudiados.

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Experimental effects of light intensity modulation on the recording and erasure of holographic gratins in BSO crystals

Cited by 19 publications

References 22 publications

Analysis of the steady-state photorefractive harmonic gratings

Analysis of the steady-state photorefractive harmonic gratings

An electron-hole transport model for the analysis of the photorefractive harmonic gratings

Redes fotorrefractivas armónicas en el marco del modelo Kukhtarev y sus extensiones

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