Digital and Gradient Refractive Index Planar Optics by Nanoimprinting Mesoporous Silicon

Anna L. Hardison, Tahmid H. Talukdar, Ivan I. Kravchenko, Judson D. Ryckman

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We report the realization of digital and gradient index flat-optics and planar waveguides using the ‘nanoimprinting refractive index’ (NIRI) technique applied to mesoporous silicon. This technique combines the distinct optical and mechanical metamaterial qualities of mesoporous silicon, including its widely tunable effective refractive index and ability to undergo plastic deformation with a near zero Poisson ratio. Nanoimprinting with premastered and reusable stamps containing analog or digital features enables the continuous or discontinuous patterning of refractive index with high contrast Δn ≥ 0.8 and subwavelength resolution. Using NIRI we experimentally demonstrate a wavefront shaping flat microlens array operating in the visible (405–635 nm) and mesoporous silicon and silica waveguides operating near 1310 nm. This study demonstrates the viability of patterning arbitrary refractive index distributions, n(x,y), on the surface of a chip while circumventing the challenges and limitations of top-down lithographic techniques – thus opening a low-cost and scalable approach for the realization of advanced planar optical technologies.

Original languageEnglish
Article number2201597
JournalAdvanced Optical Materials
Volume10
Issue number24
DOIs
StatePublished - Dec 19 2022

Funding

The authors acknowledged support from the National Science Foundation (Award nos. 1825787 & 2047015). Digital stamp fabrication was performed as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The authors acknowledged support from the National Science Foundation (Award nos. 1825787 & 2047015). Digital stamp fabrication was performed as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.

Keywords

  • GRIN optics
  • flat-optics
  • metamaterials
  • metasurfaces
  • nanomanufacturing
  • subwavelength materials
  • waveguides

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