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4h ago

Nanoscale Smith Hat Patterns Produce Chiral Laser Diffraction

The experiment shows that a single aperiodic monotile’s lack of mirror symmetry can control how light diffracts by polarization and direction.

Researchers from the Institute of Industrial Science, The University of Tokyo experimentally demonstrate unique optical behavior from a long-sought aperiodic pattern Credit Institute of Industrial Science, The University of Tokyo
Researchers from the Institute of Industrial Science, The University of Tokyo experimentally demonstrate unique optical behavior from a long-sought aperiodic pattern

Overview

  • Researchers at the University of Tokyo published results on July 29 showing that nanoscale patterns based on the Smith “hat” produce striking, pinwheel-like diffraction when hit by laser light.
  • The team fabricated the patterns on silicon nitride films with electron-beam lithography and measured how scattered light changed with beam direction and polarization.
  • Because the hat tile is not mirror-symmetric, the diffraction patterns themselves are chiral and mirroring the structure in real space reverses the optical response.
  • The observed symmetry-controlled behavior differs from conventional quasicrystals because the aperiodic monotile forces nonrepeating order and directly imprints handedness onto the diffraction.
  • Authors say the work links a 2023 mathematical discovery of the Smith hat to laboratory optics and could point to new ways to control light for polarization devices and photonics, but practical applications will require further engineering and demonstration.