This thesis investigates two systems in chip-based nonlinear optical microresonators. First is the generation of broadband frequency combs through parametric four-wave mixing and the associated phenomenon of cavity soliton formation in micro-resonators. We begin by investigating the relationship between cavity soliton based modelocking and traditional saturable absorber based modelocking. We find that a saturable absorber based modelocked laser with stimulated emission gain on only one cavity mode is dynamically equivalent to a parametrically driven cavity soliton comb. We also study the phase dynamics of the cavity soliton formation process for which we derive a set of phase equations from the governing Lugiato-Lefever equation which exhibit synchronization mechanisms akin to the Kuramoto model for coupled oscillators. These equations predict that phase anti-symmetrization preceeds phase synchronization in the cavity soliton formation process and explains the origin of the pump phase offset seen in parametrically driven cavity solitons. We then extend the concept of synchronization to systems of multiple cavity soliton frequency combs. We show that cavity solitons in evanescently coupled micro-resonators can synchronize to one another, generating synchronized pulses in the time domain and frequency locked combs lines in the spectral domain. Second is the demonstration of all-optical switching using nonlinear loss in micro-resonators. We achieve this through two means. The first is through the stimulated Raman response of silicon. Here we fabricate a silicon micro-ring that is co-resonant with both a pump field and the anti-Stokes field of the silicon material. The presence of the pump field stimulates optical loss at the antiStokes field, modulating the cavity resonance across all three regimes of coupling and demonstrating a single resonance all-optical switch. Secondly we use the two-photon absorption process of highly nonlinear organic dye molecules embedded in a polymer host. We achieve nonlinear loss induced decoupling of a cavity resonance of more than 7 dB and demonstrate the on-chip nonlinear loss of 18 cm/GW of the organic polymer.