This dissertation presents silicon-based integrated micro-resonators and waveguides as the key elements of photonic integrated circuits for on-chip optical communication and signal processing applications.; Electro-optic modulation plays a critical role in implementing space-, power- and spectrally efficient optical interconnection for high-capacity computing systems. Microring resonators exhibit a great potential to achieve compact, low power-consumption and high-speed modulators. In the first part of this dissertation, we briefly review our efforts on designing and analyzing the microring modulators. Three types of single-ring modulators are discussed, from device behavior to possible system impact. We then present a novel double-ring modulator, in which a passive ring resonator is added, enabling higher operation speed and lower power consumption. We also describe an opportunity of introducing phase modulation data formats into the on-chip communication environment. Our emphasis is placed on linking the devices’ physics to their system performance and providing potential technical solutions to physical-layer challenges of optical interconnection.; Integrated silicon waveguides not only serve as transmission medium of on-chip signaling but also form various types of devices for communication and signal processing applications. In the second part of this dissertation, we present some recent progresses in tailoring the physical properties of the silicon waveguides such as chromatic dispersion and nonlinearity. Using slot structures, the dispersion could be tailored by more than a few orders of magnitude, which is highly useful in many signal processing applications.