Design and fabrication of thin-film lithium niobate photonic devices
| Author(s) | Nelan, Sean | |
| Date Accessioned | 2023-03-01T16:54:57Z | |
| Date Available | 2023-03-01T16:54:57Z | |
| Publication Date | 2022 | |
| SWORD Update | 2022-09-21T16:09:26Z | |
| Abstract | In the last decade, lithium niobate (LiNbO3) electro-optic (EO) modulators have emerged as an attractive alternative to III-V and silicon (Si) plasma dispersion and free-carrier absorption based modulation platforms. Commercially available bulk single-crystal LiNbO3 modulators demonstrate high optical power-handling capability, low optical absorption, zero chirping, high spurious-free dynamic range (SFDR), satisfactory environmental stability and low insertion loss. However, these devices rely on low index contrast (Δn < .02) titanium (Ti)-diffused waveguides (Ti:LiNbO3) that produce a large optical mode in the EO medium. Consequentially, bulk-LiNbO3 devices suffer from large optical bending-radii and unfavorable voltage-bandwidth performance. Moreover, these devices require individual tuning through micromachining to enable broadband operation which precludes efficient mass-production. Recently, the commercial availability of crystal-ion sliced (CIS) thin-film LiNbO3 on insulator (TFLNOI) has paved the way for the development of the TFLNOI modulator, representing a technological leap which rivals the transition from Si to bulk LiNbO3 modulators. ☐ TFLNOI devices use a ridge-etched or integrated strip-loaded waveguide to confine an optical mode which is nearly 20 times smaller than that of their bulk counterparts. With this, dense integration with tight optical bending radii leads to the realization and implementation of compact optical splitters, crossings, combiners, rings and grating couplers. Several discrete devices including Mach-Zehnder modulators (MZM), phase modulators, EO and thermo-optic (TO) optical switches, ring resonators and optical frequency comb (OFC) generators have already been demonstrated on the TFLNOI platform. These devices show improved voltage-bandwidth performance, lower half-wave voltages and substantially smaller footprints than bulk LiNbO3 modulators. ☐ This work focuses on the development, fabrication and characterization of TFLNOI photonic devices and investigates techniques to increase operational bandwidth, lower optical and RF insertion loss and reduce the overall device footprint of Mach-Zehnder intensity modulators. In this, discrete optical components are designed and used to demonstrate a compact, folded, modular broadband intensity modulator in the hybrid silicon nitride (Si3N4)-LiNbO3 material platform. The device is then modified for dual-output operation and improved optical extinction ratio to facilitate use in an RF photonic link that uses a balanced photo-diode (PD) receiver pair to eliminate common-mode noise for an extremely low noise floor and high spurious-free dynamic range (SFDR). Finally, RF slow-wave electrodes are investigated on the TFLNOI platform for RF and optical index matching and state-of-the-art voltage-bandwidth performance. | |
| Advisor | Prather, Dennis W. | |
| Degree | Ph.D. | |
| Department | University of Delaware, Department of Electrical and Computer Engineering | |
| DOI | https://doi.org/10.58088/9gvw-p882 | |
| Unique Identifier | 1371441967 | |
| URL | https://udspace.udel.edu/handle/19716/32369 | |
| Language | en | |
| Publisher | University of Delaware | |
| URI | https://login.udel.idm.oclc.org/login?url=https://www.proquest.com/dissertations-theses/design-fabrication-thin-film-lithium-niobate/docview/2737139845/se-2?accountid=10457 | |
| Keywords | Fabrication | |
| Keywords | Lithium niobate | |
| Keywords | Modulator | |
| Keywords | Photonic integrated circuit | |
| Keywords | Photonics | |
| Keywords | Thin-film | |
| Title | Design and fabrication of thin-film lithium niobate photonic devices | |
| Type | Thesis |