HOW GOOD IS THE POLARIZATION SELECTION RULE FOR INTERSUBBAND TRANSITIONS

Using GaAs based quantum well infrared photodetectors (QWIPs) with eit her GaAs or InGaAs wells, we experimentally investigate the accuracy o f the polarization selection rule for conduction band intersubband tra nsitions. We employ a device structure and a light coupling geometry w here the parasitic light scattering is negligible. The experiments imp ly that the selection rule is followed to an accuracy of 0.2% for a 8. 1 mu m QWIP with GaAs wells; this degrades to 3% for a 4.6 mu m QWIP w ith In0.1Ga0.9As wells. (C) 1998 American Institute of Physics. [S0003 -6951(98)00114-4].