A Switchable Metasurface Between Meta-Lens and Absorber

Here, we propose a metasurface based on the phase change material vanadium dioxide (VO2), which can switch between the meta-lens and the absorber by controlling temperature. Before phase change, VO2 is in the insulating phase and the metasurface proposed here works as a focusing lens near the wavelength of 10.6 mu m. When the temperature rises above the phase change point (341 K), VO2 becomes metallic and the metasurface will change into a good absorber, which absorbs more than 90% of the incident light energy. Moreover, in this case, the metasurface still has a meta-lens feature that will operate on the residual light. The special application of our metasurface as a light-dose sensitive smart meta-lens for bio-imaging is discussed.