SMD PRO vs Published Data

The focusing results of a metalens simulated by SMD PRO is compared with measured data published in Ref. The intensity distribution on the focal plane (Fig. 2e in the Ref.) and FWHM (Fig. 2h in the Ref.) are in good agreement with our results (image below).

SMD PRO simulation results. Left: intensity on focal plane (I_xy). Right: intensity along the y-axis (I_y) on focal plane.

• Lens info

  • Diameter 300 µm

  • Focal length 200 µm

  • Wavelength 0.532 µm

  • Unit cell shape circle and polarization-independent

  • 1,440,000 unit cells

• Results comparison

SMD PRO

FWHM 0.46 µm

Ref.

FWHM 0.497 µm

• Parameters used in SMD PRO

  • BUILD module

    • Unit cell: SOI_TiO2_FusedSilica_wvl0.532_p0.25_cir_edge0

    • Unit cell arrangement conditions: transmittance min. 0.9 and phase error max 20 deg.

  • SIMULATE module (focusing)

    • I_xy: resolution 25 nm

    • I_y: resolution 5 nm (separate simulation to pick up FWHM at higher resolution )

    • Circular aperture used with diameter 300 µm

    • Gaussian incident beam used with diameter 300 µm

The intensity profile at the focal spot such as FWHM varies with the incident beam's intensity profile or diameter.

The authors of the Ref. used a fiber-coupled collimator to collimate a laser beam coming out of an optical fiber (see Fig. S2 in their supporting document). This collimated laser beam was incident on their metalens for focusing test. Since the authors do not provide information about the collimated laser beam, the following assumptions were made for simulation in SMD PRO.

1. The fiber used for laser beam delivery is a single-mode fiber, thus the beam profile is nearly Gaussian.

2. The diameter of the (nearly) Gaussian beam incident on the metalens is equal to the lens diameter.