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55
(a) (b)
Figure 3.12: Top view SEM images showing the difference between (a)
Type-A and (b) Type-B geometries. Note that only Type-A has mirror
symmetry about the defect mid-plane.
The lattice-shifted or Type-B geometry forces the radiation fields under the two cladding
sections to be perfectly out of phase, resulting in destructive interference and therefore
decreasing the out-of-plane radiation loss. Additionally, this geometry effectively
eliminates the Fourier component of the lattice in the Γ-Κ direction in k-space, further
reducing the radiation loss. The Fourier transform for the in-plane dielectric
distribution of Type-A and Type-B geometries is shown in Figure 3.13. Wan’s calculation
compared the propagation losses of Type-A and Type-B PCWGs in GaAs slab structures
with epitaxially grown, AlxGa1-xAs alloy lower claddings. He calculated a minimum loss
of 174nm-1 for the Type-A geometry, whereas the Type-B geometry had 68nm
transmission band in which the loss was predicted to be less than 30cm-1.
Object Description
| Title | Silicon-based photonic crystal waveguides and couplers |
| Author | Farrell, Stephen G. |
| Author email | stephenf@usc.edu; sgfarrell@yahoo.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Electrical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2008-09-05 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-20 |
| Advisor (committee chair) | O'Brien, John D. |
| Advisor (committee member) |
Dapkus, P. Daniel Steier, William Haas H., Stephan |
| Abstract | Most commercial photonics-related research and development efforts currently fall into one or both of the following technological sectors: silicon photonics and photonic integrated circuits. Silicon photonics [18] is the field concerned with assimilating photonic elements into the well-established CMOS VLSI architecture and IC manufacturing. The convergence of these technologies would be mutually advantageous: photonic devices could increase bus speeds and greatly improve chip-to-chip and board-to-board data rates, whereas photonics, as a field, would benefit from mature silicon manufacturing and economies of scale. On the other hand, those in the photonic integrated circuit sector seek to continue the miniaturization of photonic devices in an effort to obtain an appreciable share of the great windfall of profits that occur when manufacturing, packaging, and testing costs are substantially reduced by shrinking photonic elements to chip-scale dimensions. Integrated photonics companies may [12] or may not [34] incorporate silicon as the platform.; In this thesis, we seek to further develop a technology that has the potential to facilitate the forging of silicon photonics and photonic integrated circuits: photonic crystals on silicon-on-insulator substrates. We will first present a brief overview of photonic crystals and their physical properties. We will then detail a finely-tuned procedure for fabricating two-dimensional photonic crystal in the silicon-on-insulator material system. We will then examine transmission properties of our fabricated devices including propagation loss, group index dispersion, and coupling efficiency of directional couplers. Finally, we will present a description of a system for adiabatically tapering optical fibers and the results of using tapered fibers for efficiently coupling light into photonic crystal devices. |
| Keyword | photonics; photonic crystal; silicon; integrated photonics; SOI; optoelectronics; waveguides; couplers; optical fiber; tapered fiber; evanescent coupling; adiabaticity; silicon photonics |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1681 |
| Contributing entity | University of Southern California |
| Rights | Farrell, Stephen G. |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Farrell-2433 |
| Archival file | uscthesesreloadpub_Volume32/etd-Farrell-2433.pdf |
Description
| Title | Page 66 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 55 (a) (b) Figure 3.12: Top view SEM images showing the difference between (a) Type-A and (b) Type-B geometries. Note that only Type-A has mirror symmetry about the defect mid-plane. The lattice-shifted or Type-B geometry forces the radiation fields under the two cladding sections to be perfectly out of phase, resulting in destructive interference and therefore decreasing the out-of-plane radiation loss. Additionally, this geometry effectively eliminates the Fourier component of the lattice in the Γ-Κ direction in k-space, further reducing the radiation loss. The Fourier transform for the in-plane dielectric distribution of Type-A and Type-B geometries is shown in Figure 3.13. Wan’s calculation compared the propagation losses of Type-A and Type-B PCWGs in GaAs slab structures with epitaxially grown, AlxGa1-xAs alloy lower claddings. He calculated a minimum loss of 174nm-1 for the Type-A geometry, whereas the Type-B geometry had 68nm transmission band in which the loss was predicted to be less than 30cm-1. |
