Normal incidence intersubband transitions in Si-doped InGaAs multiple quantum wells

Angle- and polarization-resolved infrared techniques have been used to study the polarization selection rules of intersubband transitions in Si-doped InGaAs multiple quantum wells (MQWs). Intersubband transitions are found to be active for light, polarized both parallel and perpendicular to the MQW plane, and to show a strain dependent splitting between the corresponding transition energies. Previously reported intersubband data measured in the Brewster angle configuration for the same lattice-matched and strained Si-doped InGaAs MQWs were also reproduced.