The luminescence properties due to the delocalized exciton recombination in the asymmetric-coupled quantum well (ACQW) structure have been studied based on Ξ-type configuration.We show that the luminescence has mainly two emission peaks:one peak corresponds to the red shift relative to the central transition frequency and the other to the blue shift.Compared with the single quantum well,this quantum-confined Stark shift is very sensitive to electric field.This means that the coupling between two wells for an ACQW structure leads to the enhancement of the quantum-confined Stark effect.From this optical property of ACQW,novel ultrafast optical modulation devices and optical switch fabricated with ACQW structure can be expected in the future optical communication system.