Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical properties of bismuth-doped SiO2- or GeO2-based glass core
  optical fibers   A detailed study of optical properties of bismuth-doped fibers based on SiO2
and GeO2 glasses containing no other dopants has been carried out. To provide
important information about spectroscopic properties of IR bismuth-related
active centers (BAC) the excitation-emission fluorescence spectra for a
spectral region of 220-2000 nm have been measured. The obtained
three-dimensional spectra have been presented for different host glass
compositions: silicate, germanate, aluminosilicate and phosphosilicate.
Energy-level configuration and main radiative transitions associated with BACs
in GeO2 and SiO2 glasses have been revealed. Fluorescence lifetime analysis of
the basic radiative transitions of BAC have been carried out. It has been shown
that the energy-level schemes of BAC-Si and BAC-Ge (BAC associated with silicon
and germanium, respectively) are similar, corresponding BAC-Ge energy levels
lying 10-16% lower than those of BAC-Si. It has been determined that BAC-Si,
BAC-Ge and BAC-Si, BAC-P can exist simultaneously in bismuth-doped
germanosilicate and phosphosilicate fibers, respectively. Optical amplification
in the wavelength range 1410-1470 nm and lasing at 1460 nm in SiO2 glass fiber
doped with bismuth have been demonstrated for the first time. The optical gain
and lasing in this fiber were based on the radiative transition between the
first excited and ground energy levels belonging to BAC-Si. Anti-stokes
luminescence spectra of BAC-Si and BAC-Ge in optical fibers under the two-step
excitation have been measured and analyzed in detail.

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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph