The constantly increasing volume of information in modern society demands a better understanding of the physics and modeling of optical phenomena, and in particular, optical waveguides which are the central component of information systems. Two ways of advancing this physics are to push current technologies into new regimes of operation, and to study novel materials which offer superior properties for practical applications. This dissertation considers two problems, each addressing the above-mentioned demands. The first relates to the influence of high-order nonlinear effects on pulse collisions in existing high-speed communication systems. The second part is a study of pulse dynamics in a novel nanocomposite medium which offers great potential for both optical waveguide physics and applications. The nanocomposite consists of metallic nanoparticles embedded in a host medium. Under resonance conditions, the optical field excites plasmonic oscillations in the nanoparticles, which induce a strong nonlinear response.Analytical and computational tools are used to study these problems. In the first case, a double perturbation method, in which the small parameters are the reciprocal of the relative frequency of the colliding solitons and the coefficient of quintic nonlinearity, reveals that the leading order effects on collisions are radiation emission and phase shift of the colliding solitons. The analytical results are shown to agree with numerics. For the case of pulse dynamics in nanocomposite waveguides, the resonant interaction of the optical field and material excitation is studied in a slowly-varying envelope approximation, resulting in a system of partial differential equations. A family of solitary wave solutions representing the phenomenon of self-induced transparency are derived. Stability analysis reveals the solitary waves are conditionally stable, depending on the sign of the perturbation parameter. A characterization of two-pulse interaction indicates high sensitivity to relative phase, and collision dynamics vary from highly elastic to the extreme case where one wave is immediately destroyed by the collision, depositing its energy into a localized hotspot of material excitation. This last scenario represents a novel mechanism for "stopping light".