Over the course of this project, we have made advances in several key areas 1. Controlling spin-photon interactions using narrow-linewidth optical signals. We achieved the optimal balance between the competing needs for high speed and narrow linewidth by modulating a narrow-linewidth laser with only the frequency components needs for interaction with coherent spin dynamics. 2. Understanding fundamental spin-photon interactions in semiconductor nanocrystals. We studied the initialization and evolution of coherent spin states at room temperature, yielding a guide towards possible applications. These results were compared to theory to provide a detailed understanding of spin pumping, dynamics, and decoherence in these structures. 3. Integration of semiconductor nanocrystals in photonic systems for enhanced spin-photon interaction. We have taken a multi-pronged approach to exploring possible systems for enhancing interactions between light and spins, and integrating these systems into devices, ranging from macroscopic optical cavities, to arrays of microlens cavities, to quantum dot-impregnated integrated polymer waveguides.