Silicon Micro and Nano Photonic Devices for Photonic Integrated Circuits

Abstract

Silicon photonics has the potential to provide compact sized, high performance photonic devices to enable low cost photonic integrated circuits for telecom, datacom and other high data rate applications. Silicon as a material has a mature fabrication process developed over the years from the electronics industry, leading to smaller device sizes of the order of micrometers with precise control and lower costs compared to other photonic materials such as III/V group semiconductors and optical crystals such as Lithium Niobate.

In this thesis, silicon photonic devices on micron and 220 nm scale thicknesses are described. A novel shallow etch polarization beam splitter in micron scale silicon photonics has been designed. The nominal design has excellent device performance of low excess loss below 0.4 dB for TE and TM polarizations and polarization extinction ratio greater than 15 dB over the telecom C band of 1530-1565 nm. In addition, the nominal design is robust to fabrication error of +/- 10 nm in etch depth variation and +/- 50 nm in waveguide width variation. In nanometer scale silicon photonics, novel design of a high performance electro-optic modulator using the ultrafast electro-optic Kerr effect in silicon nanocrystals is described. Analysis of the modulator indicates a high data rate transmission of 90 Gb/s with low energy consumption of 25.13 fJ/bit and a compact ring resonator structure having a diameter of 40 micrometers. In addition, theory, design simulation, fabrication and experimental characterization of Mach Zehnder Interferometer (MZI) circuits and slot waveguide Bragg grating structures have been described on 220 nm silicon thickness. A novel slow light propagation loss of 5.1 dB/mm with group index of 12.38 near 1555 nm wavelength has been experimentally obtained in slot waveguide Bragg gratings with internal corrugation. This leads to an excellent phase shifter performance for high performance electro-optic modulators and integrated-optic sensing applications.