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 wi thin the framework of the linear model taking into account the second-order dispersion effects that the presence of the imaginary part of the dispersi on parameter of the group velocity substantially affects the pulse dynamics in a single-mode optical fiber with gain. Absorption insignificantly influ ences the dispersion characteristics of the fiber and its transformation pr operties. The possibility of the realization of "supercompression," under w hich 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 the se fibers, the propagation of the pulse peak with a faster- than-light velo city and the wavefront reversal effect are possible. (C) 2001 MAIK "Nauka/I nterperiodica".