Factors affecting optical dispersion in borate glass systems

Manal Abdel-Baki, F. A. Abdel-Wahab, Amr Radi, Fouad El-Diasty*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

150 Citations (SciVal)


Series of ternary glass systems namely, Na2 O, B2 O3, and RO (R = Ba or Mg) doped with TiO2 are synthesized. The present glasses are dictated by requirement for a small refractive index and a small nonlinear coefficient needed for waveguide and laser fabrication requirements. The effect of MgO and BaO as alkaline earth metals on the optical properties of the glass systems is investigated. The dependence of the refractive index and extinction coefficient dispersion curves on composition is carried out over a wavelength range of 0.3-2.5 μ m. Applying a genetic algorithm technique, the parameters of Sellmeier dispersion formula that fit index data to accuracy consistent well with the measurements are given. The zero material dispersion-wavelength (ZMDW) and group velocity are also determined using the refractive index data. The Fermi level is calculated exploiting the extinction coefficient dispersion curves. The absorption coefficient, both direct and indirect optical energy gaps, and Urbach energy are evaluated using the absorption edge calculations. The different factors that play a role for controlling the refractive indices such as coordination number, electronic polarizability, field strength of cations, bridging and nonbridging oxygen, and optical basicity are discussed in accordance with the obtained index data. IR spectroscopy is used as a structural probe of the nearest-neighbor environment in the glass network.

Original languageEnglish
Pages (from-to)1457-1470
Number of pages14
JournalJournal of Physics and Chemistry of Solids
Issue number8
Publication statusPublished - Aug 2007
Externally publishedYes


  • A. Oxide glasses
  • D. Optical properties

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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