Characterization of silicon micro-optical waveguides

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Journal Title
Journal ISSN
Volume Title
Faculty of Electronics, Communications and Automation | Master's thesis
Date
2008
Major/Subject
Photonics
Optoelektroniikka
Mcode
S-104
Degree programme
Elektroniikan ja sähkötekniikan tutkinto-ohjelma
Language
en
Pages
iv, 54
Series
Abstract
In modern electronic circuitry, electrical interconnects have not kept pace with increasing electronic processing speed. Various drawbacks of electrical domain viz. bandwidth limitation, signal delay, electromagnetic wave phenomenon propelled the use of optical fibers. Optical waveguides provide a novel solution because of the absence of these phenomena in the optical domain. Various materials like polymers, III-V semiconductor compounds, LiNbO3 etc. have been analyzed for fabricating optical waveguides. We have chosen silicon as a material for optical waveguides. Silicon is extensively used for complimentary metal oxide semiconductor (CMOS) transistor fabrication. Thus, to use silicon for fabricating optical components is highly favorable from a technological standpoint. In this thesis, we characterize silicon optical waveguides. Loss in 10µm wide hydrogenated amorphous silicon (a-Si:H) strip optical waveguides is estimated to be 1.5dB/cm and 0.1dB/cm in rib type silicon on insulator (SOI) optical waveguides. Reflectivity of Bragg mirror on a-Si:H strip waveguides is in the range 49-86%. We measured 0.5-1dB loss per etched mirror section for fundamental transverse electric (TE) and transverse magnetic (TM) modes propagating in SOI rib waveguide. A setup to measure birefringence in optical waveguides is discussed and its results are analyzed. Ellipsometry of 260nm thick layer of a-Si:H, deposited by plasma enhanced chemical vapor deposition (PECVD), is done to ascertain the material refractive index. Spectral behavior of a-Si:H waveguides using a supercontinuum source is also studied.
Description
Supervisor
Honkanen, Seppo; Prof.
Thesis advisor
Säynätjoki, Antti; TkT
Keywords
silicon, optics, silicon photonics, attenuation, Bragg mirror, birefringence, transmission spectrum, amorphous silicon, strip waveguides, SOI waveguides
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Citation
Permanent link to this item
https://urn.fi/urn:nbn:fi:tkk-012416