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dc.contributor.advisorQing Hu.en_US
dc.contributor.authorKhalatpour, Ali.en_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.en_US
dc.date.accessioned2021-01-06T19:35:55Z
dc.date.available2021-01-06T19:35:55Z
dc.date.copyright2020en_US
dc.date.issued2020en_US
dc.identifier.urihttps://hdl.handle.net/1721.1/129256
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, September, 2020en_US
dc.descriptionCataloged from student-submitted PDF of thesis.en_US
dc.descriptionIncludes bibliographical references (pages 103-113).en_US
dc.description.abstractTerahertz (THz) frequencies (0.5-10 THz) are among the most underdeveloped electromagnetic spectra, even though their application potentials are great in imaging, sensing, and communications. This underdevelopment is primarily due to the lack of compact and powerful THz sources. The invention of THz quantum cascade lasers (QCL) held great promise to bridge the gap between semiconductor electronic and photonic devices. However, the demanding cooling requirements for THz QCL have been a hard brake in the race for achieving compact and portable systems, and they have confined THz QCL systems to a laboratory environment. Therefore, raising the maximum operating temperature to above that of a compact cooler (>/= 235 K for single-stage thermoelectric coolers), has been a paramount long-term goal in the THz field. In this thesis, THz QCLs (at ~~ 4 THz) with a maximum operating temperature T[subscript max]= 250 K has been developed. This operating temperature enabled the construction of coherent THz radiation sources using cheap commercial single-and multi-stage thermoelectric coolers, yet with power levels sufficient for real-time imaging of beam pattern and fast spectral measurements without requiring expensive cryogenically cooled detectors. The combination of TEC-cooled THz QCLs with room-temperature cameras and detectors enables portable systems that are operable outside the laboratory environment. Furthermore, and perhaps more importantly, the demonstrated significant increase in T[subscript max] and the preservation of room-temperature NDR pave a clear path toward further increases in T[subscript max]: designing clean n-level systems based on the direct-phonon scheme with tall barriers.en_US
dc.description.statementofresponsibilityby Ali Khalatpour.en_US
dc.format.extent113 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT 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.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectElectrical Engineering and Computer Science.en_US
dc.titleNew frontiers in THz quantum cascade lasersen_US
dc.title.alternativeNew frontiers in Terahertz quantum cascade lasersen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Scienceen_US
dc.identifier.oclc1227520186en_US
dc.description.collectionPh.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienceen_US
dspace.imported2021-01-06T19:35:54Zen_US
mit.thesis.degreeDoctoralen_US
mit.thesis.departmentEECSen_US


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