F Wang, X G Guo, C Wang and J C Cao,
http://m.iopscience.iop.org/1367-2630/15/7/075009/pdf/1367-2630_15_7_075009.pdf
Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of
Microsystem and Information Technology, Chinese Academy of Sciences,
865 Changning Road, Shanghai 200050, People’s Republic of China
E-mail: jccao@mail.sim.ac.cn
New Journal of Physics 15 (2013) 075009 (12pp)
Received 18 April 2013
Published 16 July 2013
Online at http://www.njp.org/
doi:10.1088/1367-2630/15/7/075009
Abstract. The ultrafast population dynamics in electrically modulated threewell
terahertz quantum cascade lasers (QCLs) is studied by using the selfconsistent
Bloch–Poisson equations. In the modulation process, the nonequilibrium
oscillations of the population inversion are found before the
population equilibrium recovers. The equilibrium formation time increases
nonlinearly with the period number. This phenomenon stems from the nonuniform
distribution of the electric potential. In different periods, different
responses to the electrical modulation are also explored. An in-depth
understanding of electron transport in the cascade structure is obtained. Finally,
we demonstrate the feasibility of a modulation frequency up to gigahertz in
terahertz QCLs.
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