This dissertation is driven by a vision to continue improvements in system functionality by alleviating bottlenecks in interconnects and enabling the processing of large amounts of information on a chip. Light was the key for achieving long-haul interconnects 35 years ago and is now becoming the key for achieving high speed data communications on smaller scales [1-3]. The ultimate goal of this research is continue this trend to the smallest possible scale by developing a complex integrated Silicon Nanophotonic chip. Here I will present some of the building blocks for such a chip. This dissertation is divided in five chapters, organized as follows. Chapter 1 gives an overview of why optical interconnects are needed on the chip scale. Then it discusses the challenges and the advantages of using a Silicon platform for such a photonic chip. We then provide a solution to the challenges by using compact resonators to dramatically increase light-matter interaction. In Chapter 2 we demonstrate one of the most basic building blocks of a silicon nanophotonic chip ? an all-optical modulator, where one beam of light controls the propagation of another. First we present low-powered all-optical modulation using a one-dimensional photonic crystal nanocavity. Then we demonstrate ultra-fast modulation using a ring resonator device with an integrated PIN diode. The diode is used to dramatically increase the speed of typical silicon modulators to at least 20 Gbit/s. In Chapter 3 we discuss using evolutionary algorithms to design silicon nanophotonic devices that outperform human designs. In order to demonstrate the promise of evolutionary algorithms we present an example that designs a photonic crystal with a bandgap that is larger than previous human designs.
In Chapter 4 we present a new technique for achieving wavelength conversion where the wavelength of light confined in a resonator is changed by dynamically tuning the resonator. We discuss theoretically how this occurs and then demonstrate it experimentally using a ring resonator device. Finally in Chapter 5, we demonstrate photonic transitions where light is transitioned between the discrete states of a resonator, in analogy to electronic transitions in an atom.