Time-resolved buildup of a photorefractive grating induced in Bi_12SiO_20 by picosecond light pulses

Jonathan, J.M.C.; Roosen, Gérald; Roussignol, Philippe

doi:10.1364/ol.13.000224

Cited by 44 publications

(10 citation statements)

References 5 publications

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“…We previously predicted and experimentally demonstrated that photorefractive gratings in BSO crystals grow and develop after illumination by a picosecond interference pattern. 8 Our analysis is based on the consideration of the ratio of the diffusion time Td to the recombination time TR of the charge carriers. From the band-transport model, one obtains Td/TR = (A/2rL) 2 , where L is the diffusion length of the photoexcited charge carriers and A is the spacing of the grating induced by the interference of two coherent light beams.…”

Section: Preliminary Resultsmentioning

confidence: 99%

Photorefractive effect generated in sillenite crystals by picosecond pulses and comparison with the quasi-continuous regime

Pauliat

Roosen

1990

J. Opt. Soc. Am. B

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Section: Preliminary Resultsmentioning

confidence: 99%

Photorefractive effect generated in sillenite crystals by picosecond pulses and comparison with the quasi-continuous regime

Pauliat

Roosen

1990

J. Opt. Soc. Am. B

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“…3 It means that in the case of open-aperture z-scan experiments using 7-ns pulses we can expect the influence of both twophoton absorption and on-axis scattering from grating that causes a decrease of the overall radiation propagation in the far field. A spacecharge electrostatic field could be generated by pure diffusion of the excited charge carriers.…”

Section: Discussionmentioning

confidence: 99%

“…3 The transmission spectrum of BGO is presented in the inset of Fig. The sample investigated ͑crystal symmetry 23͒ has the sizes of 17ϫ 11ϫ 7.3 mm.…”

Section: Experimental Arrangementsmentioning

confidence: 99%

Third-order nonlinearities of Bi12GeO20 crystal measured by nanosecond radiation

Ganeev

Ryasnyansky²,

Palpant³

et al. 2005

Journal of Applied Physics

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Articles you may be interested inLarge femtosecond third-order optical nonlinearity of Bi3.15Nd0.85Ti3O12 ferroelectric thin films Negative nonlinear refraction is observed in the photorefractive crystal Bi 12 GeO 20 ͑BGO͒ using 7-ns, 532-nm pulsed radiation. The nonlinear refractive index of BGO is measured to be ␥ = −3.8 ϫ 10 −13 cm 2 W −1 using the z-scan technique. The self-defocusing of nanosecond pulses is attributed to the appearance of free carriers generated from defects, donors, and interband transitions. The nonlinear losses caused by two-photon absorption and self-scattering from dynamic grating are discussed. The nonlinear absorption coefficient is measured to be ␤ = 3.8ϫ 10 −8 cm W −1 . Moreover, a variation of ␥ and ␤ with intensity is observed. The comparison with self-focusing and two-photon absorption previously measured using 55-ps pulses is discussed.

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“…[25,26]. In both experiments it could be assumed that no transport took place during the photoexcitation pulse and a space-charge field buildup like that in Figure 4 was observed.…”

Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 91%

“…In Ref. [25] the observed signal was assigned to diffusion and a mobility was calculated from it, but the authors miscalculated the influence of the free-carrier lifetime, which in their case determined the exponential time-constant of the build-up, and the resulting mobility value was too large by more than an order of magnitude [20].…”

Section: Review Of Mobility Investigations Performed Using Htofmentioning

confidence: 99%

Holographic Time of Flight

Biaggio

Photo-Excited Processes, Diagnostics and Applications

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The Holographic Time of Flight (HTOF) method for the all-optical, contact-less investigation of charge transport in non-centrosymmetric insulators and semiconductors is based on the instantaneous photoexcitation of a spatially modulated distribution of charge carriers and on the linear electro-optic (Pockels) effect to visualize a charge-displacement by its associated refractive index change. It can be used with a free-carrier density so low that it does not otherwise have any detectable influence on the optical properties of a material, and with short free carrier lifetimes of the order of nanoseconds or less. HTOF is an especially striking example of how several independent linear and nonlinear light-matter interaction mechanisms can join to deliver a peculiar wave-mixing effect that is directly determined by a seemingly unrelated microscopic parameter: the free-carrier mobility. This chapter reviews the HTOF method and provides a detailed theoretical treatment that will be invaluable to experimentalists interested in applying this method to new materials. The author discusses the experimental parameters that influence the HTOF results and presents the basic assumptions and experimental conditions that allow the characterization of charge transport in the bulk of a material, with a sub-nanosecond time resolution only limited by the duration of the laser pulses, and for transport lengths down to a fraction of a micrometer. IntroductionBy illuminating a dielectric material with a pulsed laser it is possible to optically excite free electrons or holes, either from donor centers in the energy band gap between valence and conduction band, or directly by interband transitions. This leads to a transient increase in the number of free charge carriers, and therefore of the conductivity. Transient studies of current initiated by optical excitation of charge carriers lead to several ways to study charge transport processes in insulators and semiconductors.Homogenous charge-carrier photoexcitation in the bulk of a sample can be achieved by photoionization of impurity centers with energy levels inside the energy band gap. The analysis of such a homogenous photoconductivity transient gives some information on the charge transport properties, but generally delivers only indirect information on the charge-carrier mobility.On the other hand, the optical excitation of a packet of charges localized at the surface of a sample, either by interband excitation or by charge-carrier injection, is at the basis of conceptually simple methods to measure drift mobilities [1]. These methods rely on the observation of the drift of a charge-carrier packet in an applied electric field by its controlled photoexcitation and the detection of its time-of-arrival after a well-defined transport length. A well-established tool to CHAPTER 4

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Time-resolved buildup of a photorefractive grating induced in Bi_12SiO_20 by picosecond light pulses

Abstract: Photorefractive gratings are induced with picosecond light pulses in a BSO crystal. Both experiment and calculations show a buildup of the effect governed by a diffusion of the excited charge carriers that occurs after illumination.

Cited by 44 publications

References 5 publications

Photorefractive effect generated in sillenite crystals by picosecond pulses and comparison with the quasi-continuous regime

Photorefractive effect generated in sillenite crystals by picosecond pulses and comparison with the quasi-continuous regime

Third-order nonlinearities of Bi12GeO20 crystal measured by nanosecond radiation

Holographic Time of Flight

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