Reconfigurable silicon photonic devices for optical signal processing.

摘要

In this Ph.D. work, a low-power, low-loss, fast, and CMOS-compatible reconfiguration technology in developed for large-scale silicon photonic devices.;In Chapter 3, material and structural optimizations are carried out on the commonly used metallic microheaters to improve their reconfiguration speed. By appropriate pulse-excitation of these devices, sub-microsecond reconfiguration time is achieved. For the analysis of these devices, heat transport is modeled using finite-element method. Our numerical modeling results are in good agreement with our experimental results, suggesting that our modeling tool is reliable for extensive optimization purposes. We have also developed a system-level model that can describe the response of the microheater with very good accuracy. This model is a powerful tool for system-level studies of the microheater.;In Chapter 4, a new microheater architecture is proposed in which the microheater is directly fabricated over the silicon layer to utilize its high thermal conductivity for heat conduction. In this design, microheater is placed on the microdisk toward the center, and far from the optical mode. This device is fabricated on an silicon-on-insulator (SOI) wafer and the experimental results showed ≈80 ns heat propagation delay. With pulsed-excitation of these microheaters, sub-100-ns reconfiguration of the photonic device is demonstrated. The power consumption of this device with a 4 mum diameter microdisk is measured to be 1 mW per 2.4 nm resonance wavelength shift (or 265 GHz resonance frequency shift). To the best of our knowledge, this is the fastest thermal reconfiguration speed reported to this date with this level of power consumption and insertion loss.;The other major focus of this Ph.D. work, is on the design and demonstration of novel resonator-based reconfigurable photonic devices for nonlinear optics applications. In Chapter 5, a temporal coupled-mode theory is developed for four-wave mixing (FWM) in TWRs to model the performance of the proposed devices for nonlinear optics experiments. Here, a quasi-phase-matching theory in microresonators is developed for the first time that is applicable to complicated coupled-resonator structures.;In Chapter 6, a coupled-resonator device consisting of two resonators that are coupled through a Mach-Zehnder interferometer is proposed and experimentally demonstrated. This device enables the tuning of the resonance-frequency spacing up to one whole free-spectra range. This is achieved by tuning of the mutual coupling of the resonators through the interferometer coupling the two resonators. To the best of our knowledge, this the first integrated device that enables this level of tuning of the resonance frequency spacing. This device is also designed for a FWM experiment and it is shown that the resonance condition for an efficient FWM process can be fine tuned using integrated microheaters over the interferometer.;In Chapter 7, a three-element coupled-resonator device is proposed and demonstrated for FWM in silicon. This device enables the design of the frequency detuning of the signal/idler modes from the pump mode through the mutual coupling of resonators and not their length. This allows us to utilize ultra-small microdisks with very large field enhancement forFWMapplication for the first time. Wavelength conversion is demonstrated in this device and the experimental results are in good agreement with the theoretical predictions of the developed coupled-mode theory in Chapter 5.;Another design issue in the resonator-based nonlinear optics devices is the different bandwidth requirements of the interacting waves. In Chapter 8, a new interferometric coupling scheme is proposed and demonstrated that enables designing the optimum bandwidth (and coupling) condition for all the interacting waves. Microheaters are incorporated in this device to accurately adjust the coupling condition. To the best of our knowledge, this is the first design addressing this issue in resonator-based nonlinear optics on chip. (Abstract shortened by UMI.)