Calculation of temporal spreading of ultrashort pulses propagating through optical glasses

Abstract

The chromatic dispersion of optical materials causes an optical pulse to spread as it propagates through the material. The pulse spreading is produced by the dependence of the group velocity on the frequency. In this paper we evaluate the temporal spreading of a pulse as it propagates through optical glass. We evaluate the dependence of group velocity on frequency in terms of the dependence of the phase refractive index of the glass on the wavelength of light. The dependence of the refractive index on the wavelength in glass is well known through the Sellmeier formula. Results are presented for 50, 80 and 100 fs pulses propagating a distance $L$, in BK7, SF14 and Fused Silica Schott optical glasses and verified by a model of the sum of Gaussian modulated frequencies.