Photorefractive response at high modulation depths in Bi_12TiO_20

Millerd, James E.; Garmire, E.; Klein, Martin; Wechsler, B. A.; Strohkendl, F. P.; Brost, George A.

doi:10.1364/josab.9.001449

Cited by 56 publications

(12 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result, one gets complex amplitudes of the space-charge field: For t→∞ function H n (t) tends to a value given by (11). The testing of H 1 (t) reveals that increasing fringe contrast increases the recording time of the grating, which is in agreement with experimental observations [4]. The time evolution of the first three harmonic amplitudes of E sc for the modulation depth m = 0.9 and material parameters listed in Table 1 calculated from (14) are presented in Fig.2.…”

supporting

confidence: 86%

Analytical solution for temporal photorefractive response in the diffusion regime

Weinert-Rączka

Wichtowski

2009

Photon. Lett. Poland

View full text Add to dashboard Cite

Abstract-The evolution of a space-charge field during photorefractive two wave mixing in unbiased sample is considered. An approximate analytical solution describing the photorefractive material response to the interference pattern of arbitrary fringe contrast is presented. Obtained solutions are compared with the results of numerical simulations.The photorefractive (PR) effect relies on the refractive index changes induced by non-uniform illumination in the photoconductive and electro-optic material. The PR effect is commonly explained in the framework of the band transport model [1], which assumes photogeneration of free carriers, their transport and trapping in dark regions. The redistribution of carriers generates the space-charge electric field (E sc ) inside the crystal. The material equations of this model are nonlinear and coupled, therefore they do not have an exact analytical solution in a general case. One of the most often investigated geometries is the two-wave mixing (TWM) configuration where interfering waves create a sinusoidal distribution of light intensity. Several methods of the space-charge field determination in such a case were developed. The majority of research is devoted to the study of steady state solutions. The dynamics of PR grating is essentially described in the frames of two approaches. For a small contrast of interference fringes, a linearization of material equations can be made. A high fringe contrast case is usually studied by means of numerical methods. To date very few attempts to find an analytical solution for the transient response of a photorefractive crystal have been taken. For example, an approximate analytical solution for space-charge field evolution given in [2] is valid only for the grating period much larger than the Debye length. In our paper we present an alternative time-dependent analytical solution applicable for arbitrary modulation depth of the interference pattern. The relationship that describes directly the grating formation dynamics in TWM geometry without external electric field was found. The applied approach is based on the idea presented in the work [3]. * E-mail: ewa.raczka@ps.plWe consider the band transport model with one type of charge carriers (electrons), and one photoactive donor level of dopants with concentration N D which are partially compensated by shallow fully ionized acceptors with concentration N A = N A − = constant. In the considered case no external electric field is applied to the crystal, so the electron transport is caused only by diffusion. A photorefractive transport model is described by the following set of equations:where n, N D , N D + , N A are electron, donor, ionized donor and acceptor densities, respectively. S describes photoexcitation cross section, I -light intensity, γ -recombination constant, j -current density, µ -electron mobility k B -Boltzmann's constant, T -absolute temperature, ε = ε 0 ε r an electric permittivity and) charge density. Additionally, we have the external condition:The photorefractive respon...

show abstract

supporting

confidence: 86%

Analytical solution for temporal photorefractive response in the diffusion regime

Weinert-Rączka

Wichtowski

2009

Photon. Lett. Poland

View full text Add to dashboard Cite

show abstract

“…This is manifested, in particular, in a decrease in the first-harmonic amplitude, an increase in high space-harmonic amplitudes, and, in some cases, in the generation of space subharmonics of the photoretractive grating [7][8][9][10][11][12][13][14]. A meander alternating field applied to the crystal has a most pronounced effect on the nonlinearity of response [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Multiwave Interaction of Light in a Bismuth Silicon Oxide Crystal in an Applied Meander Electric Field

Mandel

2004

Russ Phys J

View full text Add to dashboard Cite

An analysis is made of photorefractive nonlinearity resulting from the interaction between the charge gratings formed in a bismuth silicate crystal in an applied meander electric field under illumination by a strong reference and two signal light beams. It is shown that the nonlinear cross interaction between the primary holographic gratings recorded in the crystal should be taken into account where the intensities of the reference and signal light beams differ from one another in magnitude (less than 300 times).

show abstract

“…The effects of material nonlinearity lying outside the linear approximation can become decisive in this region. Previous theoretical attempts [5,6,15] to enter the nonlinear domain have shown some modification of the ac response but they have not found its new general qualitative features.…”

mentioning

confidence: 97%

“…Although it was found [5][6][7] that the linear approximation in the ac case is restricted to values of the light modulation considerably smaller than 1, the concept of gradient response has been overwhelmingly used for the arrangement and interpretation of a large number of ac-photorefractive experiments; see, e.g., [2,[8][9][10] and references therein. These experiments deal not only with the recording of spatial gratings but also with nonlinear beam propagation [9][10][11], which has become topical during recent years in connection with photorefractive solitons [2,12] and possible applications [13,14].…”

mentioning

confidence: 99%

Singular Behavior of Light-Induced Space Charge in Photorefractive Media under an ac Field

et al. 2000

View full text Add to dashboard Cite

We show that a photoconductive crystal, placed in a rapidly alternating ac field and exposed to nonuniform light, exhibits singularities of the induced space charge and discontinuities of the corresponding space-charge field. The singularities appear at the local intensity maxima when the curvature of the intensity profile exceeds a certain (often very low) threshold value. We analyze the characteristic features of the singular ac response and consider its possible optical manifestations.

show abstract

Photorefractive response at high modulation depths in Bi_12TiO_20

Cited by 56 publications

References 11 publications

Analytical solution for temporal photorefractive response in the diffusion regime

Analytical solution for temporal photorefractive response in the diffusion regime

Multiwave Interaction of Light in a Bismuth Silicon Oxide Crystal in an Applied Meander Electric Field

Singular Behavior of Light-Induced Space Charge in Photorefractive Media under an ac Field

Contact Info

Product

Resources

About