Focusing with planar microlenses made of two-dimensionally varying high contrast gratings

A.B. Klemm, D. Stellinga, E.R. Martins, L. Lewis, L. O'Faolain, T.F. Krauss

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Abstract

We report on the focusing performance of reflective two-dimensionally varying high contrast grating lenses based on silicon. The combination of their subwavelength nature and their high refractive index contrast makes it possible to create highly tolerant and planar microlenses. We used a rigorous mathematical code to design the lenses and verified their performance with finite element simulations. We also investigated the effects of grating thickness, angle, and wavelength of incidence in these simulations. Experimentally, we show the evolution of the beam profile along the optical axis for a lens with a high (0.37) numerical aperture. We have explored a wide range of numerical apertures (0.1-0.93) and show that the lenses behave as expected across the full range. Our analyses demonstrate the large design flexibility with which these lenses can be made along with ease of fabrication and potential for a number of applications in micro-optics.
Original languageEnglish
Article number095104
JournalOptical Engineering
Volume53
Issue number9
DOIs
Publication statusPublished - 11 Sept 2014

Keywords

  • Diffractive optics
  • Microlens
  • Flat optics
  • Photonic crystals
  • High index contrast
  • Numerical aperture

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