Electrical and Computer Engineering ETDs

Publication Date

Spring 4-12-2021

Abstract

Silicon photonics is an attractive approach to cost-effective integrated optics due to the infrastructure established for silicon CMOS electronics. The material properties of silicon however are not ideal for optical devices. Specifically, silicon lacks the ability to easily produce light-emitting devices due to its indirect bandgap, and has a centro-symmetric crystal structure which does not facilitate the Pockels effect required for linear modulation. Conversely, lithium niobate is an excellent optical material due to its strong Pockels effect but, is a notoriously difficult material to process. One method of simultaneously overcoming the material limitations of silicon and the fabrication limitations of lithium niobate is the heterogeneous integration of the two platforms. In this dissertation we review an architecture which integrates thin-film lithium niobate and silicon photonics via bonding to simultaneously address the manufacturing difficulties associated with lithium niobate, and material property limitations associated with silicon. In this architecture, integrated systems are completely fabricated in a CMOS foundry with the exception of the final bonding step, and no etching of lithium niobate is required. An electro-optic modulator is fabricated using this architecture and characterized.

One of the primary advantages of silicon photonics is the high-yield and high-volume manufacturing integrated systems, and as such the systematic uniformity of devices and systems using this bonded, integrated architecture is also addressed. Variation in the bonding surface is discussed, and mitigation strategies are implemented to improve uniformity. Characterization methods of waveguide based devices are explored as well in order to identify systematic process variations.

Keywords

TFLN; Electro-optic modulator; Fabrication uniformity; heterogeneous integration

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

First Committee Member (Chair)

Daniel Feezell

Second Committee Member

Anthony Lentine

Third Committee Member

Mansoor Sheik-Bahae

Fourth Committee Member

Marek Osinski

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