A nanoantenna with balanced electric and magnetic dipole moments, known as the first Kerker condition, exhibits a directive radiation pattern with zero backscattering. In principle, a nanoantenna can provide even better directionality if higher order moments are properly balanced. Here, we study a generalized Kerker condition at the example of a nanoring nanontenna supporting electric dipole and electric quadrupole moments. Nanoring antennas are well suited since both multipole moments can be almost independently tuned to meet the generalized Kerker condition.

Plasmonic nanorings provide the unique advantage of a pronounced plasmonic field enhancement inside their core. If filled with a polarizable medium, it may significantly enhance its optical effects. Here, we demonstrate this proposition by filling gold nanorings with lithium niobate. The generated second harmonic signal is compared to the signal originating from an unpatterned lithium niobate surface. Measurements and simulation confirm an enhancement of about 20. Applications requiring nanoscopic localized light sources like fluorescence spectroscopy or quantum communication will benefit from our findings.

A novel‐shaped plasmonic chiral nanomaterial exhibiting circular dichroism in the near‐infrared spectral range is presented. Applying on‐edge lithography, a large area with these nanostructures is efficiently covered. This fabrication method offers tunability of the operation bandwidth by tailoring the chiral shape.

An ultra-black (A > 99%) broadband absorber concept on the basis of a needle-like silicon nanostructure called Black Silicon is proposed. The absorber comprises Black Silicon established by inductively coupled plasma reactive ion etching (ICP-RIE) on a highly doped, degenerated silicon substrate. Improved absorbers also incorporate an additional oxide capping layer on the nanostructures and reach an absorptance of A > 99.5% in the range of 350 to 2000 nm and A ∼ 99.8% between 1000 and 1250 nm. Fabrication of the absorbers is consistent with CMOS standards and requires no lithography.

We present an approach for extremely fast, wafer-scale fabrication of chiral starfish metamaterials based on electron beam- and on-edge lithography. A millimeter sized array of both the planar chiral and the true 3D chiral starfish is realized, and their chiroptical performances are compared by circular dichroism measurements. We find optical activity in the visible and near-infrared spectral range, where the 3D starfish clearly outperforms the planar design by almost 2 orders of magnitude, though fabrication efforts are only moderately increased. The presented approach is capable of bridging the gap between high performance optical chiral metamaterials and industrial production by nanoimprint technology

Antireflective surfaces composed of biomimetic sub-wavelength structures that employ the 'moth eye principle' for reflectance reduction are highly desirable in many optical applications such as solar cells, photodetectors and laser optics. We report an efficient approach for the fabrication of antireflective surfaces based on a two-step process consisting of gold nanoparticle mask generation by micellar block copolymer nanolithography and a multi-step reactive ion etching process. Depending on the RIE process parameters nanostructured surfaces with tailored antireflective properties can easily be fabricated that show optimum performance for specific applications.

In this Letter we evaluate a technique for the efficient and flexible generation of aluminum nanorings based on double patterning and variable shaped electron beam lithography. The process is demonstrated by realizing nanorings with diameters down to 90 nm and feature sizes of 30 nm utilizing a writing speed of one ring per microsecond. Because of redepositions caused by involved etching processes, the material of the rings and, therefore, the impact on the plasmonic properties, are unknown. This issue, which is commonly encountered when metals are nanostructured, is solved by adapting a realistic simulation model that accounts for geometry details and effective material properties. Based on this model, the redepositions are quantified, the plasmonic properties are investigated, and a design tool for the very general class of nanofabrication techniques involving the etching of metals is provided.

Laterally structured antireflective sub-wavelength structures show unique properties with respect to broadband performance, damage threshold and thermal stability. Thus they are superior to classical layer based antireflective coatings for a number of applications. Dependent on the selected fabrication technology the local topography of the periodic structure may deviate from the perfect repetition of a sub-wavelength unit cell. We used rigorous coupled-wave analysis (RCWA) to simulate the efficiency losses due to scattering effects based on height and displacement variations between the individual protuberances. In these simulations we chose conical and Super-Gaussian shapes to approximate the real profile of fabricated structures. The simulation results are in accordance with the experimentally determined optical properties of sub-wavelength structures over a broad wavelength range. Especially the transmittance reduction in the deep-UV could be ascribed to these variations in the sub-wavelength structures.