We investigate analytically the occurrence of modulation instability in doped fiber lasers and amplifiers using a Maxwell–Bloch description for the dopants and without making the usual parabolic-gain approximation. We find a new modulation instability occurring near the Rabi frequency, which is not predicted by the conventional complex Ginzburg–Landau model. We discuss the implications of this new instability for fiber amplifiers and lasers and analyze the effects of the saturable host absorption on the laser instabilities. Atomic detuning is shown to significantly enhance the new modulation instability, in both the normal- and the anomalous-dispersion regimes.
© 1997 Optical Society of America
Guido H. M. van Tartwijk and Govind P. Agrawal, "Maxwell–Bloch dynamics and modulation instabilities in fiber lasers and amplifiers," J. Opt. Soc. Am. B 14, 2618-2627 (1997)