Electrorefraction associated with Wannier-Stark localization instrongly coupled three-quantum-well structures

摘要

Wannier-Stark localization of heavy holes and the associatednrefractive index changes in a strongly coupled GaAs-Al0.75Gan0.25As three-quantum-well structure have been investigated.nElectroabsorption has been measured for TE polarization and the resultsncompared with simulations performed by the exciton Green's functionnmethod to reveal the dominant contributions to the differentialnabsorption at low applied electric field. The refractive index changesncalculated by Kramers-Kronig transformation are large compared withnthose arising from the quantum-confined Stark effect in conventionalnsquare quantum wells and are shown to derive from the emergence of onlynfirst-order ladder states due to the strong localization of heavy holes.nPreliminary experimental confirmation of strong electrorefractionnassociated with heavy-hole state localization is obtained at 80 meVndetuning. This effect is potentially useful for electrooptic devicenapplications