Linear dynamics of a Gaussian frequency-modulated pulse in a single-mode fiber with a complex refractive index

By using a frequency-modulated Gaussian pulse as an example, it is shown within the framework of the linear model taking into account the second-order dispersion effects that the presence of the imaginary part of the dispersion parameter of the group velocity substantially affects the pulse dynamics in a single-mode optical fiber with gain. Absorption insignificantly influences the dispersion characteristics of the fiber and its transformation properties. The possibility of the realization of "supercompression," under which the pulse duration tau (p) --> 0, as well as of compression of a pulse without initial frequency modulation, is revealed. It is shown that in these fibers, the propagation of the pulse peak with a faster- than-light velocity and the wavefront reversal effect are possible. (C) 2001 MAIK "Nauka/Interperiodica".