We realized In0.8Ga0.2As/AlAs/AlAs0.56Sb0.44 coupled double quantum wells with an extremely thin AlAs center barrier in order to decrease the energy of interband transitions to nearly 0.8 eV. By widening the In0.8Ga0.2As well for the extremely thin AIM center barrier, the interband transition energy was successfully decreased to nearly 0.8 eV while the energy of intersubband transitions was constant at 0.8 eV. Optical and structural characterizations revealed that the In0.8Ga0.2As/AlAs/AlAs0.56Sb0.44 coupled double quantum wells with the extremely thin AlAs center barrier had good optical and structural Properties. (C) 2008 Published by Elsevier B.V.