Accurate Nanofabrication Techniques for High-Index-Contrast Microphotonic Devices
Name
Barwicz TR# 717.pdf
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24.37 MB
Format
Adobe PDF
Checksum (MD5)
81cbac189357173a284e2a308633b7cc
Author(s)
Barwicz, Tymon
Date Issued
August 25, 2006
Series/Report no.
Technical Report (Massachusetts Institute of Technology, Research Laboratory of Electronics);
717
Abstract
High-refractive-index-contrast microphotonic devices provide strong light confinement
allowing for sharp waveguide bends and small dielectric optical resonators. They allow
dense optical integration and unique applications to optical filters and sensors but present
exceptional complications in design and fabrication. In this work, nanofabrication
techniques are developed to address the two main challenges in fabrication of high-indexcontrast
microphotonic devices: sidewall roughness and dimensional accuracy.
The work focuses on fabrication of optical add-drop filters based on high-indexcontrast
microring-resonators. The fabrication is based on direct-write scanning-electronbeam
lithography. A sidewall-roughness characterization and optimization scheme is
developed as is the first three-dimensional analysis of scattering losses due to sidewall
roughness. Writing strategy in scanning-electron-beam lithography and absolute and
relative dimensional control are addressed.
The nanofabrication techniques developed allowed fabrication of the most advanced
microring add-drop-filters reported in the literature. The sidewall-roughness standarddeviation
was reduced to 1.6 nm. The field polarization and the waveguide cross-sections
minimizing scattering losses are presented. An absolute dimensional control accuracy of
5 nm is demonstrated. Microring resonators with average ring-waveguide widths matched
to 26 pm to a desired relative width-offset are reported.
Description
Thesis Supervisor: Henry I. Smith
Title: Joseph F. and Nancy P. Keithley Professor of Electrical Engineering
Thesis Supervisor: Harry L. Tuller
Title: Professor of Ceramics and Electronic Materials
MIT Department
Massachusetts Institute of Technology. Research Laboratory of Electronics
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