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theses

Integrated optical interconnect technology has reached a point in which academia and industry research are dedicating many of its resources to maturing the technology and developing it for large scalability. Silicon photonics and silicon photonic-related technologies are the main contenders in driving scalability due to silicon’s advantage in being a successful mature material in other large-scale developments such as in achieving highly dense transistors. Silicon’s past success has jumpstarted silicon photonics. However, there are still many hurdles to scaling up.
One of the biggest issues with silicon waveguides is that they can be quite lossy. Despite fabrication processes becoming more advanced, the losses of single-mode silicon waveguides are still several orders worse than that in silica-based optical fibers. Typically, to reach lower losses, designers can widen or thicken silicon waveguides. However, there are various multimode-related caveats that can make this non-trivial. As such, we explore waveguide losses with a multimode perspective and provide some insight to avoid intermodal waveguide scattering that might inadvertently increase loss rather than decrease it in wider waveguides.
Another issue with waveguides is the need to bend them back and forth when routing light to various parts of a photonic integrated circuit. Dense waveguides have been proven to demonstrate low crosstalk in straight sections by creatively engineering the relative width geometry between neighboring waveguides in the form of a waveguide superlattice. However, the bending of waveguide superlattices introduces bending-related physics that can increase the crosstalk. We explore the bending regime and demonstrate dense waveguide superlattice bends of small footprint and relative crosstalk no greater than -19.6 dB for a waveguide superlattice with a minimum bending radius of 5 µm.
We also explore the sensitivities of microring-based transceiver circuits, which can drastically be reduced in performance by fabrication deviations. Furthermore, with ambient conditions such as temperature constantly changing, the performance of microrings can be unstable. More than likely, photonic integrated circuits will be packaged in systems including electronic circuits that can tune the performance of their photonic counterparts. Thus, we provide various gradient-based algorithms to enable automated tuning and thermal adaptivity for multi-microring photonic integrated circuits.

ETD_10277

Ph.D.

Includes bibliographical references

doi:10.7282/t3-xgy6-3p84

ETD doctoral

The author owns the copyright to this work.