Abstract

Advances in the growth of ultrathin semiconductor layers have allowed to realize structures showing novel physical effects and device applications. One of the most exciting developments was the ability to grow heterostructures with barrier layers thin enough that tunneling becomes important. One particular structure which has recently found much interest is an asymmetric double quantum well structure (a-DQW), which is related to double well potentials important in many other fields of physics.[1] Figure 1 depicts schematically an a-DQW structure: Out of resonance (left), the electronic wavefunctions are localized in the respective well; at resonance (right), the levels anticross, and the wavefunctions are delocalized over both wells. If one excites resonantly the WW with a short pulse having a spectrum which covers transitions to both electronic levels, a wavepacket localized in the WW is created.

© 1991 Optical Society of America