Silicon microring and microdisk-based active devices using integrated p-i-n diodes

Silicon-based integrated photonics and optoelectronics have attracted recent substantial research and development interests for integrated optical signal processing on the same material and technology platform as silicon microelectronics, compatible with the mature complementary metal-oxide-semiconductor (CMOS) fabrication technologies. Silicon photonics offer potentially low-cost building blocks for signal processing optoelectronic integrated circuits (OEICs). Among various integrated photonic device structures demonstrated on silicon to date, optical microring/microdisk resonators offer the key advantages of micrometer-scale compact size, narrowband wavelength selectivity, and can be readily coupled with integrated waveguides.;In this thesis, we propose and demonstrate a number of novel microring and microdisk-based active devices on silicon chips for optical signal processing functionalities including (i) optical modulators, (ii) electrically reconfigurable channel filters, and (iii) data format converters for clock recovery. All of these devices use silicon microring/microdisk resonators with integrated p-i-n diodes for carrier-injection based electro-optic tuning.;Silicon modulators, which encode electrical data onto a guided optical beam on a silicon chip, can be one of the key components for future optical interconnects on silicon ICs and for applications in access networks. We realize high-speed silicon microdisk resonator-based modulators using free-carrier plasma dispersion effect. The microdisk high-Q resonances enable the transmission intensity modulation upon a small free-carrier induced refractive index change. Our experiments on a 10-mum-diameter microdisk modulator demonstrate 3-dB modulation bandwidth of ∼500 MHz using a sharp resonance of Q∼17,000. GHz-speed modulation speed is expected upon optimizing the microdisk modulator structure.;Silicon reconfigurable channel filters and switches can be another key components for optical signal processing in next-generation wavelength-division-multiplexed (WDM) optical networks. We demonstrate two electrically reconfigurable channel filters using microring resonators with interferometric tunability. In one configuration, we couple a microring resonator to one arm of a Mach-Zehnder interferometer (MZI), resulting in a pair of complementary asymmetric resonance line shapes (known as Fano resonances) in the MZI output ports. We demonstrate Fano resonance line shape tuning, from resonance dips to resonance peaks in complementary manner between the two MZI output-ports, by electrically phase-tuning the other uncoupled MZI arm. Thus, the device offers a Fano resonance-based reconfigurable channel add-drop filter. In another configuration, we use an electrically tunable feedback waveguide to cross-couple with a microring resonator. This results in a two-port waveguide cross-coupled microring-based channel filter. We demonstrate tuning of the resonance wavelength, extinction ratio, and line shape by varying the feedback amplitude and phase.;Silicon microring filters also perform interesting functionality in the time-domain. Here, we demonstrate microring resonator-based data format converter for digital signal clock recovery. Our experiments show that microring filters with high Q and high extinction ratio can convert non-return-to-zero (NRZ) signals to pseudo-return-to-zero (PRZ) signals, an essential step for recovering the NRZ clock component.