A metasurface may include a substrate layer and a two-dimensional array of metallic optical pillars arranged in parallel rows extending vertically relative to the substrate layer. Gaps between adjacent pillars form optical resonators and a tunable dielectric material is positioned in the optical resonators between the pillars. A reflective layer positioned between the substrate layer and the two-dimensional array of pillars may include a two-dimensional array of elongated rectangular reflector patches arranged in parallel rows with an electrical isolation gap between adjacent rows of reflector patches. The plurality of reflector patches may be arranged lengthwise within each row with an off-resonance gap between adjacent reflector patches. The reflector patches in adjacent rows may be offset with respect to one another, such that the off-resonance gaps between adjacent reflector patches in one row are not aligned with the off-resonance gaps between adjacent reflector patches in an adjacent row.