Hybrid Nonlinear Metasurface Refractive Lens.

Nonlinear metasurfaces have been extensively studied, offering new capabilities to generate and control light. Usually, nonlinear metasurfaces are fabricated on planar substrates where the entire functionality is encoded in the metasurface design. Here, we study a new route to nonlinear metasurface-based optics by coating linear refractive elements with conformable nonlinear metasurface-skin, resulting in hybrid nonlinear refractive elements. We specifically demonstrate a hybrid nonlinear meta-lens composed of a plano-convex linear refractive lens coated with a 400 nm thick nonlinear metasurface membrane. We show that the resulting hybrid element produces light at the second harmonic frequency and focuses it according to the hybrid linear-nonlinear optical functionality. We study the spectral and polarization responses of the hybrid element and demonstrate its ability to generate an image at the second harmonic wavelength. We believe that this demonstration opens the door to a new family of hybrid nonlinear refractive elements for controlling light in new applications.