Resonant plasmonic and metamaterial structures allow for control of fundamental optical processes such as absorption, emission and refraction at the nanoscale. Considerable recent research has focused on energy absorption processes, and plasmonic nanostructures have been shown to enhance the performance of photovoltaic and thermophotovoltaic cells. Although reducing metallic losses is a widely sought goal in nanophotonics, the design of nanostructured ' black ' super absorbers from materials comprising only lossless dielectric materials and highly refl ective noble metals represents a new research direction. Here we demonstrate an ultrathin (260 nm) plasmonic super absorber consisting of a metal -insulatormetal stack with a nanostructured top silver fi lm composed of crossed trapezoidal arrays. Our super absorber yields broadband and polarization-independent resonant light absorption over the entire visible spectrum (400 -700 nm) with an average measured absorption of 0.71 and simulated absorption of 0.85. Proposed nanostructured absorbers open a path to realize ultrathin black metamaterials based on resonant absorption.

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*These authors contributed equally to this work. SUPPORTING INFORMATION:Coupled systems composed of asymmetric resonator elements have symmetric and antisymmetric resonances. In the manuscript, only the antisymmetric resonances are reported for the SRR-bar and ACSRR cases, as the amount of tuning is larger and more strongly dependent on the coupling distance than for the symmetric resonance. In Figure S1, the wavelength range is extended in order to show how both the symmetric and the antisymmetric mode are affected by the sample strain. In the case of the SRR-bar, the symmetric mode, which is largely due to the nanowire resonance, is almost completely unaffected by changing the coupling distance with the other resonator. This was discussed in greater detail in previous work 1 .

Driven by the restructuring of Germany's Renewable Energy Sources Act in 2000, the photovoltaics industry has grown tremendously, demonstrating an average compound annual growth rate of 56% in the five-year period prior to 2008. As a result of this growth and the subsequent development of the industry, the cost of photovoltaic electricity will likely reach grid-parity within the next 6-10 years (without significant technological advances.) However, for photovoltaics to generate an appreciable fraction of electricity, costs must be further reduced such that energy storage systems (batteries, hydrogen production coupled with fuel cells) can be implemented. Recently, Si microwire-array solar cells have emerged as a promising new type of low-cost solar cell with the potential for dramatically reduced Si consumption and flexible modules, while offering c-Si photovoltaic efficiencies. In this work we demonstrate the fabrication of Si microwire-array solar cells with high open-circuit voltages, short-circuit current densities and fill factors. These solar cells exhibit photovoltaic efficiencies of up to 7.9% and should achieve efficiencies of $15% with known improvements in cell design.

Crystalline Si wires, grown by the vapor-liquid-solid (VLS) process, have emerged as promising candidate materials for lowcost, thin-film photovoltaics. Here, we demonstrate VLS-grown Si microwires that have suitable electrical properties for high-performance photovoltaic applications, including long minority-carrier diffusion lengths (L n [ 30 mm) and low surface recombination velocities (S ( 70 cm$s À1). Single-wire radial p-n junction solar cells were fabricated with amorphous silicon and silicon nitride surface coatings, achieving up to 9.0% apparent photovoltaic efficiency, and exhibiting up to $600 mV open-circuit voltage with over 80% fill factor. Projective single-wire measurements and optoelectronic simulations suggest that large-area Si wire-array solar cells have the potential to exceed 17% energy-conversion efficiency, offering a promising route toward cost-effective crystalline Si photovoltaics.

Improving the temporal resolution of single photon detectors has an impact on many applications 1 , such as increased data rates and transmission distances for both classical 2 and quantum 3-5 optical communication systems, higher spatial resolution in laser ranging and observation of shorter-lived fluorophores in biomedical imaging 6 . In recent years, superconducting nanowire single-photon detectors 7,8 (SNSPDs) have emerged as the highest efficiency time-resolving single-photon counting detectors available in the near infrared 9 . As the detection mechanism in SNSPDs occurs on picosecond time scales 10 , SNSPDs have been demonstrated with exquisite temporal resolution below 15 ps [11][12][13][14][15] . We reduce this value to 2.7±0.2 ps at 400 nm and 4.6±0.2 ps at 1550 nm, using a specialized niobium nitride (NbN) SNSPD. The observed photon-energy dependence of the temporal resolution and detection latency suggests that intrinsic effects make a significant contribution.Temporal resolution in SNSPDs, commonly referred to as jitter, is characterized by the width of the temporal distribution of signal outputs with respect to the photon arrival times. This statistical distribution is known as the instrument response function (IRF), and its width is commonly evaluated as

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The realization of practical on-chip plasmonic devices will require efficient coupling of light into and out of surface plasmon waveguides over short length scales. In this letter, we report on low insertion loss for polymer-on-gold dielectric-loaded plasmonic waveguides end-coupled to silicon-on-insulator waveguides with a coupling efficiency of 79 ± 2% per transition at telecommunication wavelengths. Propagation loss is determined independently of insertion loss by measuring the transmission through plasmonic waveguides of varying length, and we find a characteristic surface-plasmon propagation length of 51 ± 4 μm at a free-space wavelength of λ = 1550 nm. We also demonstrate efficient coupling to whispering-gallery modes in plasmonic ring resonators with an average bending-loss-limited quality factor of 180 ± 8.