Control of electron population by intersubband optical excitation in potential-inserted double quantum well structures

A remarkable change in photoluminescence spectra was observed when CO2 laser light was incident to induce an intersubband transition in a novel asymmetric double quantum well structure where the second subbands of both wells are resonantly coupled, while the ground subbands are not. It is found that the observed change originates from the CO2-laser-induced transfer of electrons from one well to the other, demonstrating the controllability of electron population by means of infrared light.