Holey-Metal Lenses: Sieving Single Modes with Proper Phases
Date of this Version1-2013
Nano Lett., 2013, 13 (1), pp 159–163 DOI: 10.1021/nl303841n
We study a planar, holey-metal lens made as a set of concentric circular arrays (rings) of nanoscale holes milled in a subwavelength-thick metal film. Each nanohole-a finite-length, circular, single-mode waveguide with a radius-dependent mode index-is used as a phase-shifting element. Our experimental results confirm that the focusing properties of our polarization-independent, holey-metal lens milled in a 380-nm-thick gold film and illuminated with 531 nm light fits the analytical model well. The proposed concept could offer an alternative to conventional refraction microlenses and open up a vital path toward on-chip or fiber-end planar photonic devices for biosensing and imaging.
Nanoscience and Nanotechnology