  The luminescence spectra of a quantum cascade laser in a strong magnetic
field is influenced significantly by the presence of disorder (charged or
neutral) in the system. An externally applied magnetic field parallel to the
electron plane causes a red shift of the luminescence peak in the absence of
any disorder potential. Our results indicate that the disorder potential tends
to cancel that red shift and causes a rapid decrease of the luminescence peak.
A similar behavior was observed in a recent experiment on QCL in a parallel
magnetic field.
