Abstract

This work is devoted to the investigation of modulational instability (MI)¹ and self-phase-modulation-induced (SPM-induced) modulational instability² in the region of minimum group velocity dispersion in single-mode optical fibers. We performed theoretical calculations using an extended nonlinear Schrödinger equation, taking into account up to fourth-order dispersive effects. Our calculations show that the modulation frequency saturates at a value determined by the fourth-order dispersive parameter when the second-order dispersion approaches its minimum value. Although third-order dispersive effects do not contribute to the MI frequency,³ they introduce amplitude modulation on the pulse envelope. This leads to asymmetric behavior of periodic pulse train breakup when a long pulse undergoes SPM-induced modulational instability.

© 1991 Optical Society of America