Defects and photorefraction: A relation with mutual benefit

Abstract

Intrinsic and extrinsic defects are at the origin of photorefraction. Donor and acceptor defects define the properties of the photorefractive response in particular its dispersive behavior. This enables, e.g., targeted material design by incorporation of extrinsic defects in photorefractive media. Vice versa, defect physics benefits from photorefraction, i.e., photorefraction is successfully applied in defect studies and material analysis. Concepts for investigations make use of the great variety of nonlinear photorefractive phenomena. These include the appearance of a transient light‐induced absorption, two‐wave mixing at one‐dimensional photonic gratings, photo‐assisted self‐assembly of photonic gratings and space‐charge waves originating from oscillating photonic gratings. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optically generated small electron and hole polarons in nominally undoped and Fe-dopedKNbO3investigated by transient absorption spectroscopy

“…5 On the other hand, the analysis of light-induced formation and decay processes, monitored by the related optical absorptions, allows one to gain insight into the number densities of the metastably trapped carriers, the paths covered before recombination, the hopping of the free-electron polarons, and the detrapping of the bound hole polarons. 6 The lifetime of metastable small polarons depends, among others, on the hopping-transport length, the temperature, and the stabilization energy of the lattice deformation. Here, the hoppingtransport length equals the sum of elementary hopping steps between neighboring B cation sites spanning the distance from creation to recombination.…”

Trap saturation in InP:Fe by optical interband excitation

“…At the same time, optical formation of charge gratings is of extreme importance for optical excitation and the study of space-charge waves ͑SCW͒ in these and other semiconductor materials. 4 Let us remind the simplest, but most commonly used, monopolar model of charge grating formation ͑Fig. 1͒.…”

Thickness dependence of photo-induced light scattering in photorefractive ferroelectrics

“…For instance, it allows us to elaborate methods to either suppress or to enhance the scattering [11][12][13]. At the same time, it enables a deep macro-and microscopic insight into major properties of nonlinear optical materials [14][15][16][17]. Moreover, it can be applied to determine the conditions for an optical amplification in the frame of 2WM and 4WM, respectively [8,10].…”