ISSN:
1432-0649
Schlagwort(e):
PACS:42.40.Pa; 42.70.Gi; 42.70.Ln
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Abstract. Phase and amplitude gratings in the visible and near-infrared spectral range can be written in SodiumNitroPrusside (SNP), $\rm Na_2[Fe(CN)_5NO] \cdot 2H_2O$ , single crystals by optical excitation of infinitely long-living metastable electronic states, localized in the $\rm [Fe(CN)_5NO]^{2-}$ anions. Hence, its photorefractive effect does not depend on dopants or defects. The refractive index is modulated by more than $\Delta n = 1 \times 10^{-3}$ in the red $(632.8$ nm) and $\Delta n = 5 \times 10^{-4}$ in the near-infrared region $(1047$ nm). The absorption coefficient is modulated by about $\Delta \alpha = 100$ m $^{-1}$ at $632.8$ nm and 40 m $^{-1}$ at 1047 nm. The wavelength dependence of $\Delta n$ can be explained by strong absorption bands in the ultraviolet considering Kramers-Kronig dispersive analysis. The time constant of the write-read-erase processes and the diffraction efficiency $\eta$ depend on light intensity, wavelength and polarization of the light with respect to the crystallographic axes. After excitation of the metastable states the indicatrix is modulated only along the $a$ - and $b$ -axis of the orthorhombic system.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01833793
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