Actively Tunable Metalens Array Based on Patterned Phase Change Materials

Abstract

Recently, the metalens has been investigated for its application in many fields due to its advantages of being much smaller than a conventional lens and is compatible with nano-devices. Although metalenses have extraordinary optical performance, it is still not enough in some occasions such as wavefront detection for adaptive optics and display for large area applications. Using a metalens array is an ideal solution to solve these problems. Unfortunately, the common metalens array cannot be adjusted once it is fabricated, which limits its range of application. In this article, we designed an actively tunable metalens array for the first time by arranging the patterned phase change material Ge2Sb2Te5 (GST) appropriately. For the metalens array designed at the wavelength of 4.6 μm, it had excellent broadband performance in the range from 4.5 μm to 5.2 μm. On the other hand, by tuning the phase state of GST, the focus and display of the metalens array can be controlled, acting as switching on or off. Furthermore, any graphics constructed with patterned focal spots can be achieved when the metalens array has sufficient secondary unit cells. The proposed metalens may have potential application value in the adaptive optics and dynamic display field.

Tunable metasurfaces towards versatile metalenses and metaholograms: a review

“…Furthermore, PCMs have been widely used to make tunable metalenses, by varying the phase of the PCM through the application of external stimuli such as optical pulses, 115 thermal heating, 100 and electrical heating. 101,[116][117][118][119] A rewritable device that uses Ge 2 Sb 2 Te 5 (GST) exploits modulation of the state of GST by an optical pulse. 115 When a GST thin-film is stimulated 96 (c) Schematic illustration of metalenses that are tuned mechanically by rotating the substrate (left) and phase distribution of one of two lenses (right).…”

Multifunctional Metasurface Lens With Tunable Focus Based on Phase Transition Material

“…Large depth of focus, has great advantages in many fields such as microscopes, endoscopes, inspection cameras, etc. [45].…”

Optical magnetic lens: towards actively tunable terahertz optics

“…Many results are reported in the class of metalens based on phase-change materials. [50][51][52][53][54] Tunability of the focal length of around 10-15% is typically reported with a focusing efficiency of 20%. However, the transmitted intensity usually changes dramatically as the focal length is tuned.…”