2026-09-19T08:53:34Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1293652021-07-05T14:03:20Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Qing Hu.
Uyehara, Elise(Elise A.)
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2021-01-11T17:19:47Z
2021-01-11T17:19:47Z
2020
2020
https://hdl.handle.net/1721.1/129365
1227278167
Thesis: S.M. in Computer Science and Engineering, Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, September, 2020
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 69-70).
Terahertz radiation exhibits unique properties that make it an attractive candidate for safe imaging. Current barriers to its commercial implementation include the shortage of efficient terahertz detectors and convenient, high-powered terahertz sources. These factors combined with the strong atmospheric absorption of terahertz radiation necessitate the development of an imaging system capable of extracting small terahertz signals from the background noise. This can be achieved using a combination of heterodyne detection and a phase-locked loop to selectively lower the system noise floor while preserving signal power. In this thesis, an optical phase-locked loop using a Schottky diode mixer and 3rd order DFB QCLs is implemented to achieve a maximum SNR of 60 dB, limited by residual phase error from the high free-running linewidth of the QCLs. System limitations and alternative phase-locking configurations are discussed towards the ultimate goal of achieving a 110 dB dynamic range terahertz QCL imaging system..
by Elise Uyehara.
S.M. in Computer Science and Engineering
S.M.inComputerScienceandEngineering Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
70 pages
eng
Massachusetts Institute of Technology
MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.
http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
Phase-locking terahertz quantum cascade lasers for high dynamic range heterodyne imaging
Thesis
application/pdf
2021-01-11T17:19:46Z
Publication
Master
EECS
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="64fdde5a-63db-430c-a58b-fa821e495114">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Phase-locking terahertz quantum cascade lasers for high dynamic range heterodyne imaging</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2020</PublicationDate>
<Authors>
<Author>
<DisplayName>Uyehara, Elise(Elise A.)</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Electrical Engineering and Computer Science.</Keyword>
<Abstract>Terahertz radiation exhibits unique properties that make it an attractive candidate for safe imaging. Current barriers to its commercial implementation include the shortage of efficient terahertz detectors and convenient, high-powered terahertz sources. These factors combined with the strong atmospheric absorption of terahertz radiation necessitate the development of an imaging system capable of extracting small terahertz signals from the background noise. This can be achieved using a combination of heterodyne detection and a phase-locked loop to selectively lower the system noise floor while preserving signal power. In this thesis, an optical phase-locked loop using a Schottky diode mixer and 3rd order DFB QCLs is implemented to achieve a maximum SNR of 60 dB, limited by residual phase error from the high free-running linewidth of the QCLs. System limitations and alternative phase-locking configurations are discussed towards the ultimate goal of achieving a 110 dB dynamic range terahertz QCL imaging system..</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>