Stretchable metalens with tunable focal length and achromatic characteristics

Abstract

We propose a stretchable metalens on polydimethylsiloxane (PDMS) substrate. By stretching the stretchable metalens device along x- and y-axis directions, it exhibits highly tunable focal length and achromatic characteristics. The focal length of stretchable metalens keeps as stable and shows a good relationship to the change of the period of stretchable metalens. When the incident wavelengths are 480 nm, 530 nm, 580 nm, and 660 nm, the focal lengths of stretchable metalens can be tuned in a quite linear range by stretching the period of stretchable metalens from 450 nm to 800 nm. The tuning range of focal length is over 200% for these four incident wavelengths. All the full width at half maximum (FWHM) values for different incident wavelengths are small than 2.5 µm. It means the proposed stretchable metalens possesses the stable beam shape of focus length in the whole visible spectrum. The stretchable metalens provides an effective approach in stretchable device applications and new directions for the future designs in metalens applications, such as the next generation of 3D stereo imaging and holographic projection.