The capacity of photonic waveguides to guide and confine light allows for nonlinear interactions with modest power levels in a readily engineerable platform. Through design of the waveguide dispersion the phase-matching conditions for specific nonlinear interactions can be satisfied. Nonlinear interactions such as four-wave mixing, soliton fission, and Raman scattering allow for the generation of broadband spectra from a narrowband pump. This dissertation presents research into the generation of broadband spectra in dispersion engineered silicon nitride waveguides and microresonators. Utilizing continuous wave pumping we demonstrate parametric frequency comb generation in microresonators at repetition rates suitable for fast electronics. We explore the possibility of generating a modelocked comb spectrum in a microresonator pumped by an external cavity with an embedded optical amplifier. Coherent supercontinuum generation at 1-GHz repetiton rates is realized in silicon nitride waveguides utilizing a modelocked laser at 1 μm. We expand the limits of coherent octavespanning supercontinuum generation in silicon nitride waveguides to include low pump pulse energies and picosecond pulse durations for f-2f interferometry.