25 research outputs found
Self-Consistent Theory of the Gain Linewidth for Quantum Cascade Lasers
The linewidth in intersubband transitions can be significantly reduced below
the sum of the lifetime broadening for the involved states, if the scattering
environment is similar for both states. This is studied within a nonequilibrium
Green function approach here. We find that the effect is of particular
relevance for a recent, relatively low doped, THz quantum cascade laser.Comment: 3 pages, figures include
Quantum-mechanical wavepacket transport in quantum cascade laser structures
We present a viewpoint of the transport process in quantum cascade laser
structures in which spatial transport of charge through the structure is a
property of coherent quantum-mechanical wavefunctions. In contrast, scattering
processes redistribute particles in energy and momentum but do not directly
cause spatial motion of charge.Comment: 6 pages, 5 figures included in tex, to appear in Physical Review
Evaluation of morbidity, mortality and outcome following cervical spine injuries in elderly patients (S. A. Malik et al.)
Contains fulltext :
71260.pdf (publisher's version ) (Closed access
Theory of the ultrafast nonlinear response of terahertz quantum cascade laser structures
Using density matrix theory, the linear and ultrafast nonlinear optical properties of a recently developed terahertz quantum cascade laser are investigated. All relevant excitation regimes, from coherent Rabi flopping up to the scattering dominated stationary response, are covered by the theory. It is shown that the coherence transfer between different periods is important to describe optical effects