A fast and cheap, large-area (>1 cm(2)), high-coverage fabrication technique for periodic metallic split-ring resonator metamaterials is presented, which allows control of inner- and outer-ring diameters, gap angles, as well as thickness and periodicity. This method, based on shadow nanosphere lithography, uses tilted-angle-rotation thermal evaporation onto Langmuir-Blodgett-type monolayers of close-packed polystyrene nanospheres. Excellent agreement of the process parameters with a simplified model is demonstrated. Pronounced, tunable optical metamaterial resonances in the range of 100 THz are consistent with simulations.

We experimentally investigate the vortex induced energy losses in niobium coplanar waveguide resonators with and without quasihexagonal arrays of nanoholes (antidots), where large-area antidot patterns have been fabricated using self-assembling microsphere lithography. We perform transmission spectroscopy experiments around 6.25 and 12.5 GHz in magnetic field cooling and zero field cooling procedures with perpendicular magnetic fields up to B = 27 mT at a temperature T = 4.2 K. We find that the introduction of antidot arrays into resonators reduces vortex induced losses by more than one order of magnitude.

The cover image shows a scanning electron microscopy image of periodically arranged metallic split‐ring resonators, which are manufactured by tilted‐angle‐rotation thermal evaporation of gold onto Langmuir–Blodgett‐type monolayers of close‐packed polystyrene nanospheres. The split rings with dimensions smaller than the wavelength of light are deposited within the nanosphere gaps and form a metamaterial with pronounced, tunable optical resonances in the range of 100 THz. The presented technique allows control of the inner‐ and outer‐ring diameters, gap angles, as well as thickness and periodicity. Being a flexible and reliable alternative to electron‐beam lithography, this method should therefore pave the way towards cheap, large‐area metamaterials for applications such as perfect lenses and optical cloaking devices. For more information, please read the Full Paper “Periodic Large‐Area Metallic Split‐Ring Resonator Metamaterial Fabrication Based on Shadow Nanosphere Lithography” by H. Giessen et al. beginning . (Cover artwork by S. Hein.).

The influence of the bias voltage on emission properties of a red emitting InP/GaInP quantum dot based single-photon source was investigated. Under pulsed electrical excitation, we can influence the band bending of the p-i-n diode with the applied bias voltage and thus the charge carrier escape by quantum tunneling. This leads to control over the non-radiative decay channel and allows carrier escape times as low as 40 ps, effectively reducing the time jitter of the photon emission. We realized high excitation repetition rates of up to 2 GHz while autocorrelation measurements with g(2)(0)-values of 0.27 attest dominant single-photon emission.

We present a method to reduce the intrinsically high InP quantum dot density embedded in a Ga0.51In0.49P barrier by introducing an InGaAs quantum dot seed layer. The additional strain reduces the total InP quantum dot density by around one order of magnitude from 2×1010 to 3×109 cm−2 but only ∼1% of the InP nanostructures seem to be optically active (107 cm−2). Therefore, microphotoluminescence measurements could be accomplished without masks. We found resolution-limited photoluminescence linewidths (ΔE<100 μeV), good signal-to-noise ratios (∼65), single-photon emission behavior [g(2)(τ=0)=0.3], and excitonic decay times of typically between 1 and 2 ns. Furthermore the structural quantum dot properties were investigated.