Mid-infrared free space wavelength beam splitter based on dual frequency reflective metalens

We present a reflective metalens with a hybrid antenna structure, which can realize the beam splitting function of two wavelengths in free space. A key feature of our design is the presence of phase-independent regulation at two different wavelengths in each nanoresonator, which can generate a specific phase or a continuous sweep in the range of 0° to more than 300°. To demonstrate the wavefront manipulation ability of the array, we simulated the characteristics of wavelength beam splitting, especially the free space wavelength beam splitter with a focal length of 300 μ m and a relative focal position of 100 μ m.