The absorption and dispersion behaviors of an asymmetrically coupled quantum well (ACQW) structure are studied based on V-type system. We show that the quantum-confined Stark shift due to an electric field applied along the growth direction of ACQW leads to the detuning absorption, and the corresponding linear refraction is dramatically decreased in a smaller negative-bias voltage region. This means that refraction quenching induced by an external electric field can occur in an ACQW structure. However, the absorption and the dispersion behaviors become the same as those of the lowest excitonic state in a single quantum well structure as the negative-bias voltage further increases due to the disappearance of quantum-confined Stark effect. This means that the ACQW structure has controllable dispersion by using an external field.