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Title: Heterogeneous terahertz quantum cascade lasers
Author: Freeman, J. R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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Although terahertz quantum cascade lasers (QCLs) are promising devices for cheap, compact and coherent sources of terahertz radiation, the full potential of these lasers has not been realised. In this work we shall examine the active region design of THz QCLs and study the behaviour of heterogeneous active regions, where there are several quantum cascade designs combined in the same active region. We will present a study of the systematic design of THz QCLs and show that it is possible to systematically tune the frequency of these devices by simple modifications to the active region design. We then present some active region designs, together with results for some high-performance designs, operating around 2 THz. Two of these designs have shown high efficiency and high temperature performance at this frequency range. From this we move on to the subject of heterogeneous active regions, and present electrically switchable emission from heterogeneous THz QCLs; devices which emit at different, widely separated frequencies depending on the electrical conditions. This is the first reported electrically switchable emission from THz QCL devices without a magnetic field.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available