Silicon optical micro-resonators for optical information processing and communications applications

Optical micro-resonators with high quality factors and small mode volumes can find wide applications in nonlinear optics, quantum optics, optical information processing and communications. Silicon, the material of choices for integrated electronics, opens a door for low-cost and power-efficient photonic integrated circuits. At the 1.55 μm tele-communication window, the large refractive index and low linear absorption coefficient of silicon enables compact photonic devices. The strong optical nonlinear effects in silicon enable on-chip all-optical signal processing. This dissertation focuses on the design of silicon micro-resonators and their applications in optical information processing and communications. A coupled-mode theory (CMT) for nonlinear micro-resonators is first developed based on perturbation theory, which provides the fundamental for the design and analysis of optical devices. In Chapter 4, an optical diode for optical nonreciprocity is discussed and demonstrated. Optical nonreciprocity (ONR) is essential for the implementation of optical isolators and optical circulators. Here ONR is realized based on the optical nonlinear effects in an asymmetric optical structure that consists of cascaded two silicon microrings. The design represents a new, non-magnetic approach to on-chip ONR. One-way information transmission through the optical diode is also demonstrated based on the strong dispersion associated with microring\u27s resonance. Silicon micro-resonators also serve as building blocks for photonic integrated circuits that provide advanced functionalities. The last two chapters cover discussions on multi-channel reconfigurable microring filter bank for ultrafast optics and RF photonics applications. In Chapter 6, a 4-channel silicon nitride filter bank based on-chip pulse shaper is designed and demonstrated, which is capable of 2π-phase tuning and 30dB-amplitude control of individual frequency components in the input optical signal. In Chapter 7, an 8-channel silicon microring filter bank is developed for time-domain synthesis of RF waveforms based on silicon tunable optical delay lines. Nanosecond-reconfigurable RF waveforms are also achieved through integrating a silicon modulator with the shaper. This represents a big step towards an integrated photonic solution for RF arbitrary waveform generation