Metamaterials for High-Efficiency Photonic Integrated Circuits with Multiband Applications in Quantum and Fibre Communications

The invention of the laser in the early 1960s catalyzed the emergence of a new branch of electrical engineering now known as photonics. Since then, rapid population growth, the accelerated expansion of communication infrastructure, and the development of novel computing architectures have pushed classical electronics to their fundamental limits. Integrated photonics offers a path to faster, more efficient solutions that meet the demands of modern technologies through the generation and manipulation of optical signals. In particular, the silicon-on-insulator and silicon nitride photonic integration platforms have supported a range of applications due to their compatibility with mature complementary metal-oxide-semiconductor fabrication processes. While silicon-on-insulator enables ultra-compact devices, fast active signal modulation, and efficient coupling interfaces, silicon nitride provides low-loss waveguiding over a broad spectral range and favourable nonlinear properties. To fully benefit from the potential of these platforms, decades of research have led to the development of a library of design strategies for improving the performance of components in photonic integrated circuits. Among these, metamaterials have been established as a versatile tool that can be applied to all photonic devices. In this thesis, we leverage refractive index and dispersion engineering enabled by these subwavelength periodic structures to demonstrate significant performance gains in two critical components that can often be major sources of loss in optical circuits. First, we present a novel metamaterial waveguide architecture to demonstrate a compact and low-power thermal phase shifter for silicon-on-insulators chips. With this, we achieved a power consumption as low as 3.82 mW representing a more than five-fold improvement over regular waveguide heating. The second targeted component is grating couplers for silicon nitride waveguides. Two sets of devices are presented that cover multiple key spectral bands and both the transverse-electric and transverse-magnetic polarizations. The first was developed following a single-etch fabrication with no post-processing steps and the second uses a high-index amorphous silicon overlay to enhance the performance. Metamaterials were implemented in apodized-focalizing designs to achieve state-of-the-art coupling efficiencies. The devices presented in this thesis have strong potential in next-generation photonic integrated circuits for short-reach communication in hyperscale datacentres, global telecommunication networks, photonics manufacturing, and quantum computing.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Engineering, Electrical and Computer

Grantor dc:publisher

Carleton University

Year dc:date.issued

2026

Author dc:creator

• Fraser, William

Statement dc:rights

• Copyright © 2026 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, distribution to students, research and scholarship. Theses may only be shared by linking to the Carleton University Institutional Repository and no part may be copied without proper attribution to the author; no part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.

Language dc:language.iso

en

DOI

10.22215/etd/2026-16920

OAI identifier oai:identifier

oai:carleton.scholaris.ca:20.500.14718/45077