Fig. 1. Conceptual designs of diamond metalenses for solar-blind imaging. The left panel depicts bright-field imaging using a diamond metalens, and the right panel presents edge-enhanced imaging through a diamond vortex metalens. The insets show the corresponding phase profiles.

Fig. 2. Design principles of diamond metalens and vortex metalens. (a) Schematic illustration of the construction of diamond metalens using nanopillars with circular cross sections. (b) Absorption spectrum; the inset shows the plot of (αhv)12 as a function of photon energy (hv). (c) The refractive index (n) and extinction coefficient (k) of CVD single-crystal diamond. (d) Phase retardance and transmission of the light (λ=261  nm) modulated by diamond nanopillars with varying radii. (e) Atomic force microscope (AFM) image of a single-crystal diamond with a scanned area of 50  μm×50  μm.

Fig. 3. Fabrication and surface morphology characterization of the diamond metalens. (a) Flow chart for the nanofabrication of diamond metalenses; optical and SEM images of (b) the diamond focusing metalens and (c) the diamond vortex metalens.

Fig. 4. Focusing performance of diamond metalenses. (a) The experimental setup for the measurement of diamond metalens focusing performance. The intensity distributions of the 261 nm light after passing through the (b) diamond focusing metalens and (c) vortex metalens along the propagation direction and around the focal plane, respectively.

Fig. 5. Bright field and spiral phase contrast imaging using diamond metalenses. (a) The measurement setup for the test of imaging performance of diamond metalenses. (b) SEM images of the target samples containing various pre-defined patterns. (c) Bright field images and (d) spiral phase contrast images with edge enhancement of the same objects obtained using the diamond focusing metalens and vortex metalens, respectively, at the wavelength of 261 nm.