Strain‐Multiplex Metalens Array for Tunable Focusing and Imaging

Metalenses on a flexible template are engineered metal‐dielectric interfaces that improve conventional imaging system and offer dynamic focusing and zooming capabilities by controlling the focal length and bandwidth through a mechanical or external stretch. However, realizing large‐scale and cost‐effective flexible metalenses with high yields in a strain‐multiplex fashion remains as a great challenge. Here, single‐pulsed, maskless light interference and imprinting technique is utilized to fabricate reconfigurable, flexible metalenses on a large‐scale and demonstrate its strain‐multiplex tunable focusing. Experiments, in accordance with the theory, show that applied stretch on the flexible‐template reconfigurable diffractive metalenses (FDMLs) accurately mapped focused wavefront, bandwidth, and focal length. The surface relief metastructures consisted of metal‐coated hemispherical cavities in a hexagonal close‐packed arrangement to enhance tunable focal length, numerical aperture, and fill factor, FF ≈ 100% through normal and angular light illumination with external stretch. The strain‐multiplex of FDMLs approach lays the foundation of a new class of large‐scale, cost‐effective metalens offering tunable light focusing and imaging.