  Solitons, as stable localized wave packets that can propagate long distance
in dispersive media without changing their shapes, are ubiquitous in nonlinear
physical systems. Since the first experimental realization of optical bright
solitons in the anomalous dispersion single mode fibers (SMF) by Mollenauer et
al. in 1980 and optical dark solitons in the normal dispersion SMFs by P.
Emplit et al. in 1987, optical solitons in SMFs had been extensively
investigated. In reality a SMF always supports two orthogonal polarization
modes. Taking fiber birefringence into account, it was later theoretically
predicted that various types of vector solitons, including the bright-bright
vector solitons, dark-dark vector solitons and dark-bright vector solitons,
could be formed in SMFs. However, except the bright-bright type of vector
solitons, other types of vector solitons are so far lack of clear experimental
evidence. Optical solitons have been observed not only in the SMFs but also in
mode locked fiber lasers. It has been shown that the passively mode-locked
erbium-doped fiber lasers offer a promising experimental platform for studying
the scalar optical solitons. Vector solitons can also be formed in mode locked
fiber lasers. In this dissertation, the author presents results of a series of
theoretical and experimental investigations on the vector solitons in fiber
lasers.
