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Localized surface plasmon polaritons (LSPPs) provide an efficient means of achieving extreme light concentration. In recent years, their active control has become a major aspiration of plasmonic research. Here, we demonstrate direct control of semiconductor bowtie antennas, enabling active excitation of LSPPs, at terahertz (THz) frequencies. We modify the LSPPs by ultrafast optical modulation of the free carrier density in the plasmonic structure itself, allowing for active control of the semiconductor antennas on picosecond timescales. Moreover, this control enables the manipulation of the field intensity enhancements in ranges of four orders of magnitude.

The design, manufacturing and application of electrowetting-based liquid lenses in optical devices are discussed. Results are presentedof applying this lens in miniature autofocus and zoom cameras, optical recording and illumination systems. Conclusions: We presented the working principle and a concept for mass manufacturing of liquid lenses and we demonstrated that they can be used for focusing and zooming in miniature cameras, for dual-layer readout inBlu-ray Disc optical recording systems and for dynamic effects in illumination systems. This shows that liquid lenses can have a significant impact on future miniature optical devices.

Transmission gratings that combine a large diffraction angle with ahigh diffraction efficiency and low angular and wavelength dispersion could be used to collect sunlight in a light guide. In this paperwe determine what characteristics a grating should have in order tobe useful for such a solar concentrator. To this end we compare thediffractive properties of polarization gratings and classical surface relief gratings. It is found that polarization gratings and classical surface relief gratings have qualitatively comparable diffractive properties as long as their thickness-parameters are within the same regime. The diffraction efficiency of these gratings can be closeto 100% for a broad range of incoming angles when the period is large compared to the wavelength of the incoming light. This no longerholds for small-period gratings. For solar concentrators the more easily producible surface relief gratings are preferred over polarization gratings.

Luminescent solar concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We introducea phosphor with close-to-optimal luminescent properties and hardlyany reabsorption. A problem for use in a luminescent concentrator isthe large scattering of this material; we discuss possible solutions for this. Furthermore, the use of broad-band cholesteric filters to prevent escape of luminescent radiation from this phosphor is investigated both experimentally and using simulations. Simulations arealso used to predict the ultimate performance of luminescent concentrators.

Luminescent concentrators would allow for high concentration if losses by reabsorption and escape could be minimized. We present new phosphors and filters that facilitate this. Another type of lightguide-based concentrators, diffraction-based, is discussed as well.

We report conversion efficiencies of experimental single and dual lightguide luminescent solar concentrators. We have built several 5x5cm2 and 10x10 cm2 LSC demonstrators, consisting of c-Si photovoltaiccells attached to luminescent lightguides of Lumogen F Red 305 dyeand perylene perinone dye. The highest overall efficiency obtained was 4.2% on a 5x5 cm2 stacked dual lightguide using both luminescentmaterials. To our knowledge this is the highest reported experimentally determined efficiency for c-Si PVs based LSCs. Furthermore, we also produced a 5x5 cm2 LSC specimen based on an inorganic phosphor layer with an overall efficiency of 2.5%.

A perceptual experiment was conducted to measure the visibility of black-level differences in the proximity of a bright glare source. In a controlled viewing environment, visual difference thresholds were adaptively measured using dark, shadow-detail images shown on a high dynamic range liquid crystal display while an external LED lamp was used to induce intra-ocular glare over a small range of eccentricities. This high-contrast situation is relevant to HDR displays which may have bright regions in displayed images as well as to viewingenvironments which include lamps or other light sources. The resulting difference thresholds are modeled with a combination of the CIE total glare equation, the DICOM contrast visibility model, and a newestimate of adaptation luminance.