| Free carrier based modulation mechanisms are investigated for application to compound semiconductor devices, and the limits of free carrier based tuning are examined. A GaAs based analog of silicon-on-insulator technology is proposed to address the issue of substrate leakage loss. Of particular interest are the material development and the lateral wet oxidation process to create vertical current apertures. Very low-loss GaAs on oxide waveguides are demonstrated. Heterogeneous wafer bonding is utilized to create a hybrid GaAs/InP device, with an InGaAsP active region optimized for use as a depletion mode modulator. Microdisk resonators with a Q of over 8000 are demonstrated.;Thermal tuning is proposed as an alternate mechanism for silicon based devices. A unique tunable resonator based mirror, the wavelength selective reflector, is simulated and characterized in detail, and this device could find application as a functional building block in a photonic integrated circuit or as a cavity mirror in a tunable laser. Extensive simulation and modeling of the efficiency of thermal tuning is performed, and a design with thermal tuning efficiency greater than 90% is proposed. Laterally coupled, high index contrast microring devices require very precise lithography, and a one-step dielectric masking process using the e-beam resist XR-1541 is developed. Silicon processing techniques are developed and optimized, and a ring resonator with Q of 96,000 is demonstrated. In order to address issues with traditional thermal tuning approaches, a process to create doped semiconductor heater elements is developed, and these heater elements are used to thermally tune several high-Q resonator devices. |
