Multi-height metasurface for wavefront manipulation fabricated by direct laser writing lithography.

We introduce two types of dielectric metasurfaces, consisting of 3 × 3 regions, which manipulate wavefront by different feature heights. Both polarization-dependent and polarization-independent metasurfaces are realized for phase depth of 0 ∼ 2π at 1550 nm, with considerable average transmittance of 80.1 and 85.1 %, respectively. The phase modulation capability can be extended over a broadband range of 1460.1-1618.0 nm for optical communications, by carefully designing nanofeature sizes. Moreover, the entire metasurfaces with nanofeatures of varying heights can be fabricated in a single process by using direct laser writing with high-precision, which is beneficial for mass production and promising in developing efficient and ultracompact devices.