Holey-metal lenses: sieving single modes with proper phases.
basic_science · Level V
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- Record sourced from PubMed, PMID 23244006.
- Also identified by DOI 10.1021/nl303841n.
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Abstract
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.