Real-time amyloid aggregation monitoring with a photonic crystal-based approach.

We propose the application of a new label-free optical technique based on photonic nanostructures to real-time monitor the amyloid-beta 1-42 (Aβ(1-42)) fibrillization, including the early stages of the aggregation process, which are related to the onset of the Alzheimer's Disease (AD). The aggregation of Aβ peptides into amyloid fibrils has commonly been associated with neuronal death, which culminates in the clinical features of the incurable degenerative AD. Recent studies revealed that cell toxicity is determined by the formation of soluble oligomeric forms of Aβ peptides in the early stages of aggregation.

Resonant absorption of a chemically sensitive layer based on waveguide gratings.

A colorimetric sensor providing a direct visual indication of chemical contamination was developed. The sensor is a combination of a chemically sensitive dye layer and a resonant waveguide grating. Enhancement of the light absorption by the photonic structure can be clearly seen.

Low-loss germanium strip waveguides on silicon for the mid-infrared.

Mid-infrared photonics in silicon needs low-loss integrated waveguides. While monocrystalline germanium waveguides on silicon have been proposed, experimental realization has not been reported. Here we demonstrate a germanium strip waveguide on a silicon substrate.

Cocaine detection by a mid-infrared waveguide integrated with a microfluidic chip.

A germanium (Ge) strip waveguide on a silicon (Si) substrate is integrated with a microfluidic chip to detect cocaine in tetrachloroethylene (PCE) solutions. In the evanescent field of the waveguide, cocaine absorbs the light near 5.8 μm, which is emitted from a quantum cascade laser.

Understanding of photocurrent enhancement in real thin film solar cells: towards optimal one-dimensional gratings.

Despite the progress in the engineering of structures to enhance photocurrent in thin film solar cells, there are few comprehensive studies which provide general and intuitive insight into the problem of light trapping. Also, lack of theoretical propositions which are consistent with fabrication is an issue to be improved. We investigate a real thin film solar cell with almost conformal layers grown on a 1D grating metallic back-reflector both experimentally and theoretically.

A virtual optical probe based on localized Surface Plasmon Polaritons.

A confined, evanescent nano-source based on the excitation of Surface Plasmon Polaritons (SPP) on structured thin metal films is proposed. With the help of a suitable cavity, we numerically demonstrate that it is possible to trap SPP over a spatial region smaller than the diffraction limit. In particular, the enhanced plasmonic field associated with the zero-order cavity mode can be used as a virtual probe in scanning near-field microscopy systems.