The conditions for the appearance of modulation instability of a two-wave p
acket formed by two unidirectional strongly interacting modes traveling in
a two-mode fiber waveguide are studied. The possibility of the existence of
modulation instability in the region of normal dispersion and the effect o
f the initial conditions of fiber excitation on the development of modulati
on instability are demonstrated. (C) 2000 MAIK "Nauka/Interperiodica".