  The existing metasurfaces with ultrathin volume for asymmetric transmission
were often constructed by metal with low efficiency in optical frequency, and
could not realize the optical asymmetric transmission and focusing
simultaneously. Although the acoustic asymmetric focusing in asymmetric
focusing lens (AFL) was realized, the obtained focal point was accompanied by
large sidelobe. To solve those problems, an AFL with dual-layer metasurfaces
designed by using dielectric materials can realize optical asymmetric
transmission and focusing simultaneously in this paper. Furtherly, through
optimizing the design theory of AFL, the near-zero-sidelobe (NZS) focusing can
be realized on the subwavelength scale. The NZS asymmetric focusing of the
optimized AFL is effective in broadband, which is expected to possess
tremendous potential in the optical micro-nano processing, quantum
communication, optical micromanipulation, etc.
