TUNNELING ASSISTED MODULATION OF THE INTERSUBBAND ABSORPTION IN DOUBLE QUANTUM-WELLS

We present a new efficient modulator structure in which electron tunneling between asymmetric coupled quantum wells is used to populate or deplete the ground level for the infrared (IR) absorption, leading to externally controlled IR absorption at two different wavelengths (here 10.2 and 11.4-mu-m). The temperature dependence of the modulation depth is measured. We have used photoluminescence and photoluminescence excitation spectroscopies to analyze the space charge effects in the double quantum wells, and to estimate the carrier concentration in each well as a function of bias. The behavior of the device has been simulated using a self-consistent model.