Negative absorption coefficient of a weak electromagnetic wave caused by electrons confined in rectangular quantum wires in the presence of laser radiation
Analytic expressions for the absorption coefficient (ACF) of a weak
electromagnetic wave (EMW) caused by electrons confined in rectangular
quantum wires (RQWs) in the presence of laser radiation are calculated
using the quantum kinetic equation for electrons in the case of
electron-optical phonon scattering. The dependence of the ACF of a weak
EMW on the intensity E 01 and the frequency Ω1 of the external laser
radiation, the intensity E 02 and the frequency Ω2 of the weak EMW, the
temperature T of the system and the size L (L x and L y) of the RQWs is
obtained. The results are numerically calculated and discussed for
GaAs/GaAsAl RQWs. The numerical results show that the ACF of a weak EMW
in RQWs can have negative values. Thus, in the presence of laser
radiation, under proper conditions, a weak EMW is increased. This is
different from the similar problem in bulk semiconductors and from the
case without laser radiation.
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