Femtosecond optical Kerr effect measurements in silicate glasses

Abstract

The optical Kerr effect was measured with 130-fs laser pulses for a variety of metal-doped silicate glasses, including pairs of glasses with comparable refractive index and Abbe number but different dopant cations. The nonlinear response appeared to be instantaneous within the resolution of the experiment, matching the measured autocorrelation function of the incident laser pulses, and therefore potentially useful in ultrafast photonic switching applications. We explain the absence of any detectable slow nuclear components through a detailed time-domain analysis of the contributions to an optical Kerr effect measurement made with ultrashort pulses. This analysis describes nonresonant vibrational contributions that are temporally indistinguishable from electronic contributions. The measured third-order susceptibilities of the Ti-, Nb-, and La-doped glasses were significantly overestimated by semiempirical models based on linear material parameters, such as the model developed by Lines [J. Appl. Phys.69, 6876 (1991)] and the equation given by Boling–Glass–Owyoung [IEEE J. Quantum Electron.QE-14, 601 (1978)].