The objective of the research is to improve two disparate aspects of optical communication: multiplexing flexibility and bandwidth density of optical communication systems by developing and experimentally demonstrating power division multiplexing and high-speed integrated microring modulators. Power division multiplexing improves the multiplexing flexibility of the optical network by permitting optical communication signals that share the same carrier frequency to be added together at disparate transmitters that do not cooperate with each other. This work demonstrates such a signal can be demodulated at a single standard coherent transmitter, and analyzes the effect of differing polarization states, baud rates, and chromatic dispersion between the two signals. The bandwidth density of optical communication links is improved by characterizing space- and energy efficient high-speed microring modulators fabricated on a foundry platform. Several additional technologies including blind subcarrier demodulation, an integrated optoelectronic oscillator, and an integrated linearized modulator are also considered.