Tunneling-induced high efficiency four-wave mixing in an asymmetric   quantum wells
  An asymmetric double quantum wells (QWs) structure with resonant tunneling is suggested to achieve high efficient four wave mixing (FWM). We analytically demonstrate that the resonant tunneling can induce high efficient mixing wave in such a semiconductor structure with a low light pump wave. In particular, the FWM conversion efficiency can be enhanced dramatically in the vicinity of the center frequency. This interesting scheme may be used to generate coherent long-wavelength radiation in solid-state system. 
Hui Sun, Shuangli Fan, Hongjun Zhang, and Shangqing Gong
quant-ph cond-mat.other physics.optics