Effects of fabrication errors on the focusing performance of a sector metalens
Stafeev S.S., Nalimov A.G., O’Faolain L., Kotlyar M.V.

 

Samara National Research University, 34, Moskovskoye shosse, Samara, 443086, Samara, Russia,
IPSI RAS – Branch of the FSRC “Crystallography and Photonics” RAS, Molodogvardeyskaya 151, 443001, Samara, Russia,
Cork Institute of Technology, Cork, Ireland

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Abstract:
Using e-beam lithography, a 16-sector spiral metalens was fabricated in an amorphous silicon, capable of converting linearly polarized incident light into an azimuthally polarized optical vortex. When illuminated by a 633-nm linearly polarized laser beam, the metalens generated a near-surface subwavelength focal spot equal to 0.75 of the incident wavelength at full-width of half-maximum intensity. The focusing performance of the spiral metalens was numerically shown to be sensitive to the deviation of the factual microrelief from the calculated height. For the designed microrelief height, a circularly polarized incident beam was focused into a bright ring with a reverse energy flow occurring at its center. For the microrelief height other than  the designed one, the energy backflow effect did not occur.

Keywords:
metalens, metasurface, subwavelength focusing, FDTD-method, SNOM, energy backflow.

Citation:
Stafeev SS, Nalimov AG, O’Faolain L, Kotlyar MV. Effects of fabrication errors on the focusing performance of a sector metalens. Computer Optics 2018; 42(6): 970-976. DOI: 10.18287/2412-6179-2018-42-6-970-976.

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