Optical materials with high transmittance, low reflectance, and low energy absorption are important components for technologies such as laser systems, touch displays, sensors, and stealth devices. However, the antireflection properties conveyed by commonly used multilayer coatings are restricted to narrow wavelength ranges and strongly depend on the incident angle.

Joachim Spatz, Max Planck Institute for Medical Research, Heidelberg, and University of Heidelberg, Germany, and colleagues have developed a nanopillar surface that overcomes these challenges. In the first step, periodically spaced gold nanoparticles were deposited on a fused silica substrate through block copolymer micelle lithography. Using electroless deposition, the particle size could be further adjusted before the resulting pattern was used as the mask for reactive ion etching.

The team obtained materials with excellent optical properties in the visible and particularly the near-infrared part of the spectrum. Importantly, high transmittance and low reflectance were retained at different angles and polarization of the incident light. Furthermore, the surfaces were stable against contamination and human touch, and showed high resistance against laser-induced damage. According to the researchers, this method should be transferable to other substrates used in optical devices.

• Nanostructured Stealth Surfaces for Visible and Near-Infrared Light,
  Z. Diao, M. Kraus, R. Brunner, J.-H. Dirks, J. P. Spatz,
  Nano Lett. 2016.
  DOI: 10.1021/acs.nanolett.6b03308