Ultrashort Gaussian pulse-width expansion and shape deformation induced by group velocity dispersion

摘要

Pulse-width expansion and pulse-shape deformation of an ultrashort Gaussian pulse induced by both low and high order group velocity dispersion were theoretically analyzed in terms of energy conservation and coupled equations for three wave radiations. As an example, the optical parametric interaction processes in a negative uniaxial crystal of CsLiB6O10 with 50 fs of ultrashort Gaussian pulse were simulated. The results indicate that the degree of the pulse expansion induced by low and high order group velocity dispersion is determined by both the wavelength of the incident wave and the crystal length. A pulse could be expanded to 1.41 times its initial value as a crystal length equals the dispersion length and further heavily expanded with decreasing wave-length and increasing crystal length. The pulse expansion induced by high order group velocity dispersion using an incident wavelength of 213 nm is 1.6 times that when using 532 nm in a 50 fs pulse width without chirp modulation, and the symmetry deformation and the frequency pushing phenomena of the ultrashort pulse shape are also found.