Vincent Paeder

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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(More)
Finding the optimal structure to enhance light trapping in thin film silicon solar cells has attracted much attention in the previous decades. However, because of problems in integrating theory and experiment, there are only few comprehensive contributions that provide guidelines for the optimal design of such structures. In this work, a realistic thin film(More)
We demonstrate a concurrent polarization-retrieval algorithm based on a multi-heterodyne scanning near-field optical microscopy (MH-SNOM) measurement system. This method relies on calibration of the polarization properties of the MH-SNOM using an isotropic region of the sample in the vicinity of the nanostructures of interest. We experimentally show the(More)
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. This device is ideal for (bio-)chemical sensing applications.
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(More)
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. It is designed for single mode transmission of light in transverse magnetic (TM) polarization(More)
Scanning near-field optical microscopy (SNOM) is a popular tool to overcome the diffraction limit for the investigation of subwavelength-scale optical structures. For nearly 30 years, various configurations have been implemented to characterize the interactions of the electromagnetic field with nanostructures in the near field. An accurate understanding of(More)
Based on a mid-infrared waveguide fabricated from Germanium on Silicon substrates, we present a concept of chemical sensors in aqueous solutions. The sensing scheme is utilizing the evanescent wave in a single-mode waveguide, and the absorption spectrum of chemicals dissolved in liquids. The waveguide is coupled to a single-mode mid-infrared quantum cascade(More)
A Si/Ge based, single mode, mid-infrared optical waveguide, is used as an evanescent sensor in liquid matrix. The selectivity is achieved by the use of quantum cascade lasers (QCLs) tuned to the maximum absorption of a given analyte. The cocaine detection in human saliva at 5.81 microns is chosen as a pilot application to demonstrate the technology. Light(More)
Superprism-based deflection of an optical beam is observed in a photonic crystal composed of a triangular lattice of pillars infiltrated with a liquid crystal. The device is based on a Silicon-on-insulator substrate and operates in the telecommunications band. The experimental results show a wavelength shift of 0.76 μm/nm, in reasonable agreement with(More)