Quantum-confined Stark effects in coupled InAs/GaAs quantum dots

We report the effects of tunnel coupling on the Quantum-Confined Stark Effect (QCSE) for excitons in InAs/GaAs coupled quantum dots (CQDs). As the barrier separating the dots is reduced, the zero-field dipole moment and the polarizability are both found to increase. This systematic variation as a function of barrier thickness is due to factors including the formation of molecular wavefunctions, the electron/hole effective masses, and the CQD structural properties. The dipole moment for the interdot exciton is found to be up to 100 times larger than that of the intradot exciton resulting in a predominantly linear shift with field. The ability to control the QCSE of the exciton in a single CQD could be useful for a new class of single photon optical switches and tunable emitters.