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69
Determining the loss for the short-wavelength band from the transmission data proved
somewhat futile due to lack of resolvable Fabry-Perot peaks. However, it’s clear from the
data that the peak-to-valley ratios are smaller for the short-wavelength band than for the
long-wavelength band, meaning the structure is has higher propagation loss on the high
frequency side of the spectrum.
3.5 Suspended Membrane W1 Type-A Directional Couplers
It is a well understood phenomenon that a lightwave propagating in an optical
waveguide can, under phase matching conditions, transfer its energy to another
waveguide when the two devices are in close proximity. Based on this principle of
coupled power, directional couplers have become an important component of optical
communication systems and integrated optics. If the modes of the individual
waveguides have equal phase velocities, i.e. equal propagation constants, complete
power transfer is possible and any desired ratio of coupling can be achieved by properly
selecting the coupling distance or wavelength of operation. This characteristic has
extended the capabilities of coupled-waveguide systems to include power division and
narrow-band wavelength filtering. Furthermore, if either or both of the waveguides
consist of materials whose refractive index can be locally manipulated through some
electro-optic effect [6], [8], [11], [16], [42] or free carrier modulation [36], it is possible
to create variable power splitters, optical switches, and optical modulators by exercising
control over the individual propagation constants.
The equations that govern the amplitude of the fields in coupled waveguide systems are
canonical and their derivation will not be repeated here. Marcuse [30] has an excellent
treatment of coupled mode theory applied to directional couplers formed from dielectric
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 80 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 69 Determining the loss for the short-wavelength band from the transmission data proved somewhat futile due to lack of resolvable Fabry-Perot peaks. However, it’s clear from the data that the peak-to-valley ratios are smaller for the short-wavelength band than for the long-wavelength band, meaning the structure is has higher propagation loss on the high frequency side of the spectrum. 3.5 Suspended Membrane W1 Type-A Directional Couplers It is a well understood phenomenon that a lightwave propagating in an optical waveguide can, under phase matching conditions, transfer its energy to another waveguide when the two devices are in close proximity. Based on this principle of coupled power, directional couplers have become an important component of optical communication systems and integrated optics. If the modes of the individual waveguides have equal phase velocities, i.e. equal propagation constants, complete power transfer is possible and any desired ratio of coupling can be achieved by properly selecting the coupling distance or wavelength of operation. This characteristic has extended the capabilities of coupled-waveguide systems to include power division and narrow-band wavelength filtering. Furthermore, if either or both of the waveguides consist of materials whose refractive index can be locally manipulated through some electro-optic effect [6], [8], [11], [16], [42] or free carrier modulation [36], it is possible to create variable power splitters, optical switches, and optical modulators by exercising control over the individual propagation constants. The equations that govern the amplitude of the fields in coupled waveguide systems are canonical and their derivation will not be repeated here. Marcuse [30] has an excellent treatment of coupled mode theory applied to directional couplers formed from dielectric |
