| With the ever expanding demand for communication bandwidth,optical interconnections are gradually taking place of the traditional metalwires in both long and short distance communication. In today’s densewavelength division multiplexing systems, optical filters, as the essentialcomponent, with high order “box-like” frequency performance are in urgentdemand. An existing popular solution for high order reconfigurable filter isto employ the micro-ring resonators in cascaded or parallel coupledconfiguration. However, it is challenging for the device design andfabrication to precisely align all resonances, especially when the couplinginduces frequency shift has to be taken into consideration. In this thesis, twonovel structures of optical resonators based on self–coupled opticalwaveguides (SCOW) are proposed. The SCOW resonators are standing-wave resonators where both the clockwise and counterclockwise modes areco-excited and coherently interfered. In actively tunable configuration, theresonators can demonstrate versatile frequency performances. Split orenhanced resonance dips,“box-like” second-order response can begenerated in a single SCOW resonator. In the meantime, the bandwidth ofthe resonance is also tunable. The different resonance schemes will betheoretically discussed using transfer matrix, and validated throughexperimental results. Single channel, dual channel and broadened stopchannel are observed through active tuning of coupling parameters withinresonators. Due to their unique working scheme, compactness, andversatility in frequency domain, the SCOW resonator could be adapted inwide range of applications in integrated optical systems. A possible application as an all-optical temporal differentiator is experimentallydemonstrated. The asymmetric SCOW resonator can be reconfigured to givefirst-order or second-order differential performances, while the symmetricSCOW resonator can perform first-order differentiation and other formatconversion. |
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