Silicon-based Photonic, Plasmonic, and Optomechanic Devices a Dissertation Submitted to the Department of Electrical Engineering and the Committee on Graduate Studies of Stanford University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

The integration of optical devices and electronic devices on the same platform is currently a gateway into many research and practical applications. Because silicon and silicon compatible materials have dominated electronic development, optical devices must also conform to the silicon platform. One of the greatest challenges in building such an integrated opto-electronic system is the development of an efficient Si-compatible light emitter. In this thesis, we develop several Si-based nano-photonic devices for the control of light at the nano-scales. However, several Si-compatible materials and light emitters have low index of refraction (n), and high degrees of confinement using only index contrast and total internal reflection is difficult. We design high quality (Q-) factor photonic crystal nanobeam cavities for a variety of materials with low index, such as SiO2 (n = 1.46), silicon rich oxide (n = 1.7), and silicon nitride (n = 2.0), all with Q > 5, 000 and mode volumes Vm < 2.0(λ/n) . We employ these cavity designs to a variety of active materials, including Si-nanocrystal doped silicon oxide, Erdoped amorphous silicon nitride (Er:SiNx), and InAs quantum quantum dots (QDs) in GaAs. By placing emitters in these ultrasmall, high-Q cavities, we demonstrate that the cavity enhances emission processes. We show that the free carrier absorption processes are greatly enhanced in the Si-nanocrystal nanobeam cavities at both room and cryogenic temperatures, up to an order of magnitude compared to bulk. In addition, we demonstrate that nanobeam cavities made of Er:SiNx have enhanced absorption and gain characteristics compared to earlier designs that included silicon in the cavity. Because of the reduced losses stemming from absorption, we observe