Coherent optical communications systems are of higher sensitivity than that in systems employing the direct detection. However, interferences such as the wavefront distortion and the random vibration of polarization caused by the turbulent atmosphere limit the development of terrestrial coherent wireless optical communications system. This paper presents a novel heterodyne optical wireless communications system and method based on the grating writing and reading of the multiple-quantum-we Udevice (MQW). The MQW, a new generation of photoelec-tric device developed in 1990's, is of the attractive features including high sensitivity and fast response. Compared with the conventional coherent detection method, our method eliminates the complicated intermediate-frequency tracking system. Experimental results show that our method can repress the wavefront distortion introduced in transmission through the atmosphere.