We theoretically study the effects of bias-controlled interdot tunneling in
vertically coupled quantum dots on the emission properties of spin excitons in
various bias-controlled tunneling regimes. As a main result, for strongly
coupled dots we predict substantial reduction of optical fine structure
splitting without any drop in the optical oscillator strength. This special
reduction diminishes the distinguibility of polarized decay paths in cascade
emission processes suggesting the use of stacked quantum dot molecules as
entangled photon-pair sources.Comment: 12 pages, 4 figures, submitted to a APS journa
