2026-09-19T12:57:42Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/624562022-01-13T07:54:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Qing Hu.
Chan, Chun Wang Ivan
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2011-04-25T16:01:50Z
2011-04-25T16:01:50Z
2010
2010
http://hdl.handle.net/1721.1/62456
711180404
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 153-157).
The as yet unattained milestone of room-temperature operation is essential for establishing Terahertz Quantum Cascade Lasers (THz QCLs) as practical sources of THz radiation. Temperature performance is hypothesized to be limited by upper laser level lifetime reduction due to non-radiative scattering, particularly by longitudinal optical phonons. To address this issue, this work studies highly "diagonal" QCLs, where the upper and lower laser level wave functions are spatially separated to preserve upper laser level lifetime, as well as several other issues relevant to high temperature performance. The highly diagonal devices of this work performed poorly, but the analysis herein nevertheless suggest that diagonality as a design strategy cannot yet be ruled out. Other causes of poor performance in the lasers are identified, and suggestions for future designs are made.
by Chun Wang Ivan Chan.
S.M.
157 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
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http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
Characterization and analysis of highly diagonal Terahertz Quantum Cascade Lasers
Thesis
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Publication
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<Abstract>The as yet unattained milestone of room-temperature operation is essential for establishing Terahertz Quantum Cascade Lasers (THz QCLs) as practical sources of THz radiation. Temperature performance is hypothesized to be limited by upper laser level lifetime reduction due to non-radiative scattering, particularly by longitudinal optical phonons. To address this issue, this work studies highly "diagonal" QCLs, where the upper and lower laser level wave functions are spatially separated to preserve upper laser level lifetime, as well as several other issues relevant to high temperature performance. The highly diagonal devices of this work performed poorly, but the analysis herein nevertheless suggest that diagonality as a design strategy cannot yet be ruled out. Other causes of poor performance in the lasers are identified, and suggestions for future designs are made.</Abstract>
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