Figure 1
From: Shaping a Subwavelength Needle with Ultra-long Focal Length by Focusing Azimuthally Polarized Light
Design and effect of the planar metalens. (a) Sketch of shaping subwavelength needle with planar metalens induced by azimuthally polarized beam with vortical phase. The light spot on the screen in the foreground is the real focal spot taken by a CMOS camera. The vortical wavefront is denoted by the helical structure inside the incidence beam and the polarization state is presented by the space-variant arrows. (b) Schematic configuration of the planar metalens. R1, Rn and RN represent the radius of the 1st ring, nth ring and the outmost ring, respectively and Δd represent the width of the rings which is fixed at 1.2 μm for all the rings. (c) Optical microscope image of the fabricated planar metalens. Inset: Sectional SEM image.
