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107
stationary burner system in which heat distribution is unpredictable and depends on
several factors such as flame composition, gas flow rate, and inherent temperature
gradients of the heat source. The uniform hot-zone assumption eliminates the need for
complicated fluid mechanics analysis as the taper transition follows the very simple
formula:
( ) 0 [ 0 ] r z = r exp − z L (5.6)
where r0 is the initial fiber diameter and again z is the distance along the taper. The
advantage of this taper transition is that the taper angle decreases approximately linearly
on a log scale and is therefore somewhat coincident with the local taper angle calculated
by Love and Henry. Thus, tapers with this geometry are readily made adiabatic.
Villatoro, et al. [48] reported an experiment in which fibers were tapered using the flame
brush technique. They report that 80% of the tapers fabricated in their experiment had
less than 0.15dB loss. Figure 5.5 shows the taper angle calculated for fibers with taper
transitions as described in Equation 5.6 and for those whose taper transitions are
sinusoidal in nature. All fiber tapers were assumed to transition from an initial diameter
of 125Im to a final diameter of 1Im. It is clear from the figure that for a given “hot-zone”
length, fibers with exponential transitions have shallower taper angles, and therefore
lower excess loss, than their sinusoidal counterparts.
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 118 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 107 stationary burner system in which heat distribution is unpredictable and depends on several factors such as flame composition, gas flow rate, and inherent temperature gradients of the heat source. The uniform hot-zone assumption eliminates the need for complicated fluid mechanics analysis as the taper transition follows the very simple formula: ( ) 0 [ 0 ] r z = r exp − z L (5.6) where r0 is the initial fiber diameter and again z is the distance along the taper. The advantage of this taper transition is that the taper angle decreases approximately linearly on a log scale and is therefore somewhat coincident with the local taper angle calculated by Love and Henry. Thus, tapers with this geometry are readily made adiabatic. Villatoro, et al. [48] reported an experiment in which fibers were tapered using the flame brush technique. They report that 80% of the tapers fabricated in their experiment had less than 0.15dB loss. Figure 5.5 shows the taper angle calculated for fibers with taper transitions as described in Equation 5.6 and for those whose taper transitions are sinusoidal in nature. All fiber tapers were assumed to transition from an initial diameter of 125Im to a final diameter of 1Im. It is clear from the figure that for a given “hot-zone” length, fibers with exponential transitions have shallower taper angles, and therefore lower excess loss, than their sinusoidal counterparts. |
