Demonstration of focal length tuning by rotational varifocal moire metalens in an ir-A wavelength

This paper reports an experimental demonstration of moire metalens which shows wide focal length tunability from negative to positive by mutual angle rotation at the wavelength of 900 nm. The moire metalens was developed using high index contrast transmitarray meta-atoms made of amorphous silicon octagonal pillars, which is designed to have polarization insensitivity and full 2 pi phase coverage. The fabricated moire metalens showed focal length tunability at the ranges between +/- 1.73 - +/- 5 mm, which corresponds to the optical power ranges between +/- 578 +/- 200 m(-1) at the mutual rotation between +/- 90 degrees. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement