| In optical fibers and photonic integrated circuits (PIC's), the signal polarization can undergo random rotations. Since strong confinement (SC) microphotonic devices are polarization sensitive, a chip-scale polarization rotator is beneficial for the realization of chip-scale integrated optics. Moreover, control over polarization states of photon(s) is necessary for realization of quantum information technology in optical domain. Optical microdisks vertically-coupled to a waveguide bus due to the precise control over coupling distance in fabrication and relative ease of dense integration have become increasingly important as a building block for photonic integrated circuits. Both passive and active devices have been demonstrated including channel dropping filters, tunable resonant filters and switches, intensity modulators, phase modulators, laser sources, and WDM demultiplexers.; In this research it has been proposed and experimentally observed preferential polarization mode conversion and signal amplification due to the existence of non-zero, asymmetric, and geometry dependent cross-polarization coupling coefficients between non-orthogonal modes of the waveguide and the vertically-coupled active microdisk. A theory based on coupled mode theory (CMT) is developed to realize microdisk-waveguide system as a narrowband polarization rotator.; An integrated structure consisting of a polarization splitter, a microdisk as a narrowband polarization rotator and a combiner is proposed to be applicable in fiber communication and integrated optics. A broadband polarization rotator on ridge waveguides was designed. However, it is concluded that microdisk application for a polarization rotator is helpful to reduce the device size at the cost of bandwidth. Tuning of the microdisk resonance is required when the operating wavelength is changed.; By incorporation of the two properties of the active microdisk as a polarization rotator and tunable phase shifter, two-microdisk device is demonstrated as a narrow-band amplifier and also a potential candidate to control the polarization state of light through its ability to span the Poincare sphere. This will promise applications in quantum information technology.; At the end, active microdisk application in an optical code division multiple access (OCDMA) system and the necessity of inclusion of a polarization rotator in this system has been examined. |
