Wang, Mohan
(2021)
Three-Dimensional Integrated Photonics in Transparent Substrates Enabled by Femtosecond Laser Fabrication.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Unlike integrated electronic circuits that are built mostly on silicon wafers, integrated photonic devices involve a great variety of materials and platforms. The development of integrated photonic devices in both 2-D and 3-D architectures in each material and platform presents distinct fabrication challenges. The research in this dissertation explores the femtosecond laser as a versatile cross-platform manufacturing tool to fabricate 3-D photonic structures in transparent optical substrates.
This dissertation first presents the fabrication of multiplexable and distributed optical sensors in silica and sapphire optical fiber with high radius of curvature surfaces. Using a diffraction-limited oil-immersion fabrication setup, a reel-to-reel laser direct writing system was established to deposit laser energy inside optical fibers with micrometer precision. Through careful tuning of laser-matter interaction to form nanograting in fiber core, Intrinsic Fabry-Perot Interferometer arrays were fabricated with a high fringe visibility of 0.49 and low insertion loss of 0.002 dB per sensor. The temperature sensitivity, cross-talk, and spatial multiplexability of sensor arrays were investigated in detail. By continuously introducing nanograting as artificial Rayleigh scattering centers, femtosecond laser-fabricated Rayleigh scattering enhanced section could achieve an optimized propagation loss of 0.01 dB/cm with drastic improvement of the signal-to-noise ratio of over 35 dB for Optical Frequency-Domain Reflectometry-based distributed sensing. Long-term high-temperature performance was successfully demonstrated with improved thermal stability.
This dissertation also explores the fabrication of high-density 3-D topological photonic circuits in glass substrates with flat surfaces. Inspired from solid-state physics, topological photonics has found potential applications such as quantum information processing and defect-resistant lasing devices. Through careful control of the multiphoton laser-matter interaction in the femtosecond time scale and nanometer spatial scale, we demonstrate the fabrication of high-density coupled and low-loss 3-D waveguide arrays with varying index profiles. This dissertation presents the experimental verification of lattice braiding, Thouless pumping under the presence of disorder, and the topological pumping in a higher-order system.
In sum, the dissertation studies the optics science of femtosecond laser-matter interaction and unveil the potentials of femtosecond laser as a powerful fabrication tool for 3-D photonic device fabrication for studies in optics science and for photonics applications in communication and sensing.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
26 January 2021 |
| Date Type: |
Publication |
| Defense Date: |
26 October 2020 |
| Approval Date: |
26 January 2021 |
| Submission Date: |
1 October 2020 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
137 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Electrical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
femtosecond laser manufacturing; optical fibre sensor; device fabrication; extreme environment sensing |
| Date Deposited: |
26 Jan 2021 18:51 |
| Last Modified: |
26 Jan 2021 18:51 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/39715 |
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