Abstract: Theoretical formulations based on a coupled-mode theory and a supermode theory are developed for discussing transfer efficiency of guided electron waves in coupled quantum well structures. We apply a coupled-mode theory to electron waveguide couplers in the weak coupling regime and show that the transfer efficiency will not be greater than 100%. In the strong coupling regime, we can appropriately handle the electron waves in coupled quantum well waveguide structures by introducing a supermode theory, and demonstrate that the transfer efficiency is always less than 100%. We discuss the underlying physics in an attempt to gain an insight into the transfer efficiency related issues. Calculations for specific semiconductor quantum well structures such as GaAs/AlGaAs quantum wells are given for quantitative illustrations. !18
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