The invention relates to the active optics phase conjugate method and the imaging device, the optical switch. It constructs the mode separation/integration convertor by the optical waveguide array which is set together at one end, the optics field couples with each other; it is set separately in the other end. It leads the optical wave into the separating optical waveguide by the separation/integration convertor, then to achieve the active optics phase conjugate by adjusting the phase and the swing. It can solves the imaging problem in many limit condition such as big size, high quality, super quick focal variation, long distance and so on. So it can be used in the field of the computer-human conversation, the robot optics, the integrate circuit photoetching, information storage, the military affairs, the energy source, the biology and the light communication network.