Degenerate two-photon absorption spectra in Bi2O3:B2O3 glasses

Degenerate two-photon absorption (TPA) spectra in binary xBi(2)O(3):(100 - x)B2O3 (x = 60, 70 and 80 mol%) glasses are measured by an open-aperture Z-scan technique. The degenerate TPA coefficient, beta, obtained at a fixed photon energy increases with Bi2O3 content (e.g., 12.8 +/- 2.1 and 17.7 +/- 3.0 cm/GW at 2.34 eV for x = 60 and x = 80, respectively), while beta becomes larger at higher photon energy (e.g., 3.2 +/- 0.5 cm/GW at 1.81 eV and 15.1 +/- 2.5 cm/GW at 2.51 eV for x = 70). The degenerate TPA spectra are reproduced by using a simple formula based on a two-parabolic band model for the electronic structure of the glasses containing heavy metal oxides. (C) 1999 Elsevier Science B.V. All rights reserved.