Third-order optical nonlinearities and their ultrafast response in Bi2O3-B2O3-SiO2 glasses

Nonresonant-type homogeneous Bi2O3-B2O3-SiO2 glasses were prepared by melting. The third-order optical nonlinear susceptibility chi((3)), which was determined by measurement of third-harmonic generation, increased with increasing concentrations of Bi2O3 in the glass. The maximum chi((3)) estimated was 9.3 x 10(-12) esu in glass that contained 92 wt. % of Bi2O3. chi((3)) values of these glasses mere enhanced by the small optical bandgap. These glasses also exhibited an ultrafast response time, less than 200 fs, when a degenerate four-wave mixing method with a femtosecond laser was used. indicating that the nonlinearity of these glasses originated mainly from pure electronic polarization. (C) 1999 Optical Society of America [S0740-3224(99)02711-3].