Effect of oscillator strength and intermediate resonance on the performance of resonant phonon-based terahertz quantum cascade lasers

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DOIResolve DOI: http://doi.org/10.1063/1.4795614
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TypeArticle
Journal titleJournal of Applied Physics
ISSN0021-8979
Volume113
Issue11
Article number113109
SubjectDensity matrix formalism; Device optimization; Devices under tests; Electric field domain; Electrical instability; Oscillator strengths; Radiative transitions; Terahertz quantum-cascade lasers; Optimization; Design
AbstractWe experimentally investigated the effect of oscillator strength (radiative transition diagonality) on the performance of resonant phonon-based terahertz quantum cascade lasers that have been optimized using a simplified density matrix formalism. Our results show that the maximum lasing temperature (T max) is roughly independent of laser transition diagonality within the lasing frequency range of the devices under test (3.2-3.7 THz) when cavity loss is kept low. Furthermore, the threshold current can be lowered by employing more diagonal transition designs, which can effectively suppress parasitic leakage caused by intermediate resonance between the injection and the downstream extraction levels. Nevertheless, the current carrying capacity through the designed lasing channel in more diagonal designs may sacrifice even more, leading to electrical instability and, potentially, complete inhibition of the devices lasing operation. We propose a hypothesis based on electric-field domain formation and competition/switching of different current-carrying channels to explain observed electrical instability in devices with lower oscillator strengths. The study indicates that not only should designers maximize Tmax during device optimization but also they should always consider the risk of electrical instability in device operation.
Publication date
LanguageEnglish
AffiliationInformation and Communication Technologies; National Research Council Canada
Peer reviewedYes
NPARC number21270465
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Record identifier42a89c03-276e-440f-9310-9f2e21b6b756
Record created2014-02-12
Record modified2016-05-09
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