Reversibly reconfigurable GSST metasurface for broadband beam steering and achromatic focusing in the long-wave infrared.

Active optical metasurfaces promise compact, lightweight, and energy-efficient optical systems with unprecedented performance. Chalcogenide phase-change material GeSbSeTe (GSST) has shown tremendous advantages in the design of mid-infrared active metasurfaces. However, most of the GSST-based active metasurfaces can only work efficiently within a narrow frequency range.

Dielectric metalens for miniaturized imaging systems: progress and challenges.

Lightweight, miniaturized optical imaging systems are vastly anticipated in these fields of aerospace exploration, industrial vision, consumer electronics, and medical imaging. However, conventional optical techniques are intricate to downscale as refractive lenses mostly rely on phase accumulation. Metalens, composed of subwavelength nanostructures that locally control light waves, offers a disruptive path for small-scale imaging systems.