Design of polarization-independent reflective metalens in near infrared waveband

Metalens has received extensive concern in recent years. Design of a polarization-independent reflective metalens was proposed baesd on Au in infrared waveband. MgF₂ was chosen as the dielectric spacer of the metalens. All simulations were carried out by using the finite-difference time-domain(FDTD) software. Results show that the proposed metalens has the same effect on different polarized light and can work well in the range of 700 - 850 nm and one-focus works best in the range of 750 - 800 nm. When the incidence wavelength is chosen as 800 nm, the proposed metalens can also work well for one-focus and multi-focus. At that time, the focal length of one focus, dual focus and three focus are 9.6, 6.6 and 4.7 μm, respectively. Different focus requirements can be realized according to the characteristics of the metalens.