Electric-field-induced anti-Stokes photoluminescence in an asymmetric GaAs/(Al,Ga)As double quantum well superlattice

We have used photoluminescence (PL) spectroscopy to study the population pr operties of an asymmetric GaAs/(Al,Ga)As double quantum well superlattice, which represents a simplified version of the active region of a quantum cas cade laser. The investigation focuses on the anti-Stokes PL signal of the n arrower well, which is observed for excitation between the excitonic states of the two quantum wells and sufficiently high electric field strengths. I n this case, the photocarriers are only excited in one of the two wells, an d the signal gives direct evidence for transport of electrons and holes thr ough the (Al,Ga)As barriers. An analysis of the electric-field dependence o f conventional PL as well as anti-Stokes PL demonstrates that population in homogeneities for the electronic states can be determined. [S0163-1829(99)1 6547-0].