Cascaded meta-devices for novel applications

The manipulation of focused light beams is widely used in our lives, such as camera lenses and signal transmission. Although there are traditional lenses that realize off-axis focusing, the requirements of tilting need extra space, and the tilting stage hinders its compact integration. These disadvantages hinder the development of device miniaturization or increased construction complexity. Meta-devices composed of artificial nanostructures can manipulate the incident electromagnetic wave's phase, polarization, and amplitude. Meta-devices show excellent performance and novel applications to meet optical demands. The significant advantages of meta-devices are their new properties, lighter weight, and compact size. Here, we demonstrate cascaded meta-devices for focal length tuning in the z-axis (1-dimensional, 1D), focal spot manipulation in the x-y plane (2-dimensional, 2D), and x-y-z axis (3-dimensional, 3D). The varifocal meta-devices are used for bioimaging and 6G signal transmission.