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113
the pulling did not start until the 80th timestep. The power transmission curve has
several oscillations which appear near timestep 280. We attribute these to temporary
bowing of the taper waist caused by the gas flow and heat of the flame when the flame
was too close to the fiber. These oscillations were gradually damped as the flame
position was manually adjusted to avoid this problem. The transmission abruptly falls to
zero near timestep 770. This was due to the breaking of the fiber caused by a software
glitch. At the time the fiber broke its diameter was approximately 7.5Im. The power
collected just before the fiber broke was about 80% of its value before the taper began.
This could at least partly be attributed to bending losses in the fiber caused by the
displacement of the linear translation stages that occurred as the fiber was pulled. This
25% loss in power could also have been caused by reflections due to local index changes
of the silica taking place as a result of the extreme temperature increase during heating.
0 200 400 600 800
0.00
0.01
0.02
0.03
0.04
Power Out
Fiber Diameter
Time
Throughput Power, mW
TE Throughput Power of Tapered Fiber During Tapering Process
0
20
40
60
80
100
120
140
Diameter, um
Figure 5.8: Transmission of fiber during tapering process (left axis).
Diameter of fiber taper waist during taper process (right axis).
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 124 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 113 the pulling did not start until the 80th timestep. The power transmission curve has several oscillations which appear near timestep 280. We attribute these to temporary bowing of the taper waist caused by the gas flow and heat of the flame when the flame was too close to the fiber. These oscillations were gradually damped as the flame position was manually adjusted to avoid this problem. The transmission abruptly falls to zero near timestep 770. This was due to the breaking of the fiber caused by a software glitch. At the time the fiber broke its diameter was approximately 7.5Im. The power collected just before the fiber broke was about 80% of its value before the taper began. This could at least partly be attributed to bending losses in the fiber caused by the displacement of the linear translation stages that occurred as the fiber was pulled. This 25% loss in power could also have been caused by reflections due to local index changes of the silica taking place as a result of the extreme temperature increase during heating. 0 200 400 600 800 0.00 0.01 0.02 0.03 0.04 Power Out Fiber Diameter Time Throughput Power, mW TE Throughput Power of Tapered Fiber During Tapering Process 0 20 40 60 80 100 120 140 Diameter, um Figure 5.8: Transmission of fiber during tapering process (left axis). Diameter of fiber taper waist during taper process (right axis). |
