Accession Number : ADP006777

Title :   Two-Center Model Explains Photorefractive Properties of KNbO sub 3:Fe,

Corporate Author : OSNABRUECK UNIV (GERMANY F R) FACHBEREICH PHYSIK

Personal Author(s) : Holtmann, L. ; Kuper, G. ; Buse, K. ; Loheide, S. ; Hesse, H.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : KNbO3 has favourable photorefractive properties for applications in fast nonlinear optics such as image processing, coherent light amplification, or self-pumped phase conjugation. Desirable is the optimization of the sensitivity connected with the response time and the refractive index change. Only little is known about the centers involved in the photorefractive effect of KNbO3. Previous models were based on the assumption of iron impurities occuring in two valence states, Fe(2+) and Fe(3+), as sources and traps for the redistribution of charges. But these models cannot explain a nonlinear response of photoconductivity on light intensity already observed earlier. Measurements of photoconductivity, light-induced absorption, refractive index change and grating phase shift in a KNbO3:Fe crystal are carried out. As suggested for BaTiO3 we use a charge transport model including deep and shallow traps to explain both the photoconductivity and light-induced absorption in KNbO3:Fe looking for a complete set of model parameters.

Descriptors :   *PHOTOCONDUCTIVITY, *NONLINEAR OPTICS, ABSORPTION, AMPLIFICATION, CRYSTALS, IMAGE PROCESSING, IMAGES, IMPURITIES, INTENSITY, IRON, LIGHT, MEASUREMENT, MODELS, NONLINEAR OPTICS, OPTICS, OPTIMIZATION, PARAMETERS, PHASE SHIFT, PROCESSING, REFRACTIVE INDEX, SENSITIVITY, TRANSPORT, TRAPS, VALENCE, REFRACTION, POTASSIUM, OPTICAL IMAGES, ARGON LASERS, HOLOGRAMS, SYMPOSIA.

Subject Categories : Optics
      Holography

Distribution Statement : APPROVED FOR PUBLIC RELEASE