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Group Unveils First Flat Lens

The first in a series of ultra-thin optics developed as a part of the group’s work on nanoscale antenna phased arrays, earlier this week, researchers Francesco Aieta, Patrice Genevet, and Mikhail Kats among others unveiled a flat plasmonic lens operational at telecom wavelengths.

Just 60 nanometers thick, the effectively two-dimensional lens made of patterned gold on silicon is capable of producing images free of the achromatic aberrations suffered by conventional refractive optics. Rather than building up phase delays as light travels through the varying thickness of a conventional lens, the bending of the beams at each spot on the flat lens is the instantaneous result of a nanoantenna’s discontinuous phase response. It is thus altering the underlying mechanism for focusing light that the new lens frees its focal area of defects for normal incident light.

In the same paper, the group of researchers also presents the proof of concept for a similarly designed axicon, an optical element for the transformation of a Gaussian beam into a non-diffracting Bessel beam.

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