Figure 2
From: Shaping a Subwavelength Needle with Ultra-long Focal Length by Focusing Azimuthally Polarized Light
Characterization of the planar metalens focusing. (a) Schematic of the experimental setup. Abbreviations for optical components: HWP: half wave plate. HFG: holographic fork grating. SWP: S-waveplate. OBJ: objective lens. QWP: quarter waveplate. POL: linear polarizer. The helical structures represent the vortical phase. The two components QWP and POL inside the green dash box are only used to measure the stocks parameters. (b) Experimentally recorded diffraction pattern of linear polarized beam with vortical phase, which was created by the holographic fork grating. (c) Experimental intensity pattern of the APV beams after being modulated by the S-waveplate. The green arrows indicated the polarization states of the light beam. (d) The field pattern of the APV beam after being filtered by a linear polarizer at different angles. The orientations of the polarizer are indicated by the green arrows. (e) Intensity distribution at the focal plane which locates at 150 μm away from the metalens.
