Author
Michael Nagel
Bio: Michael Nagel is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Terahertz radiation & Terahertz spectroscopy and technology. The author has an hindex of 25, co-authored 130 publications receiving 3393 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this paper, a promising approach for the label-free analysis of DNA molecules using direct probing of the binding state of DNA with electromagnetic waves at THz frequencies is reported, which provides a drastically enhanced sensitivity enabling analysis down to femtomol levels.
Abstract: We report on a promising approach for the label-free analysis of DNA molecules using direct probing of the binding state of DNA with electromagnetic waves at THz frequencies. Passive THz resonator devices based on planar waveguides are used as sample carriers and transducers for THz transmission analysis. In comparison to a formerly used free-space detection scheme, this method provides a drastically enhanced sensitivity enabling analysis down to femtomol levels. We examine the potential of our approach on biologically relevant DNA samples and demonstrate the detection of single base mutations on DNA molecules.
521 citations
TL;DR: Time-resolved terahertz transmission analysis of polynucleotides demonstrates a strong dependence of the complex refractive index on the binding state (hybridized/denatured) of deoxyribonucleic acid (DNA) molecules, which can be inferred by monitoring THz transients and hence identify polyn nucleotides by detecting the binding of unknown polyn DNA sequences to known probe molecules.
Abstract: We present a promising approach for the label-free characterization of genetic material. Time-resolved terahertz (THz) transmission analysis of polynucleotides demonstrate a strong dependence of the complex refractive index on the binding state (hybridized/denatured) of deoxyribonucleic acid (DNA) molecules. By monitoring THz transients, one can thus infer the binding state of oligo- and polynucleotides, and hence identify polynucleotides by detecting the binding of unknown polynucleotide DNA sequences to known probe molecules. A broadband experimental demonstration in a free-space configuration, as well as a discussion of the potential application for next generation gene chips is presented.
409 citations
TL;DR: The effective refractive index measured by terahertz time domain spectroscopy shows a good agreement between the theoretical and experimental results indicating a lower dispersion for THz porous fiber compared to THz microwires.
Abstract: Porous fibers have been identified as a means of achieving low losses, low dispersion and high birefringence among THz polymer fibers. By exploiting optical fiber fabrication techniques, two types of THz polymer porous fibers--spider-web and rectangular porous fibers--with 57% and 65% porosity have been fabricated. The effective refractive index measured by terahertz time domain spectroscopy shows a good agreement between the theoretical and experimental results indicating a lower dispersion for THz porous fiber compared to THz microwires. A birefringence of 0.012 at 0.65 THz is also reported for rectangular porous fiber.
224 citations
TL;DR: Electro-optic characterization yields a record high value χ(2)(yyz) = 122 pm/V for the second-order susceptibility of the strained silicon waveguide and a strict linear dependence between the applied modulation voltage V(mod) and the resulting effective index change Δn(eff).
Abstract: We demonstrate for the first time a fully integrated electro-optic modulator based on locally strained silicon rib-waveguides. By depositing a Si3N4 strain layer directly on top of the silicon waveguide the silicon crystal is asymmetrically distorted. Thus its inversion symmetry is broken and a linear electro-optic effect is induced. Electro-optic characterization yields a record high value χ(2)yyz = 122 pm/V for the second-order susceptibility of the strained silicon waveguide and a strict linear dependence between the applied modulation voltage Vmod and the resulting effective index change Δneff. Spatially resolved micro-Raman and terahertz (THz) difference frequency generation (DFG) experiments provide in-depth insight into the origin of the electro-optic effect by correlating the local strain distribution with the observed second-order optical activity.
190 citations
TL;DR: A novel resonant THz sensor for the label-free analysis of DNA molecules that allows the direct detection of DNA-probe molecules at functionalized electrodes via hybridization and can be extended to a parallel analysis of multiple DNA sequences.
Abstract: We report on a novel resonant THz sensor for the label-free analysis of DNA molecules. The sensor allows the direct detection of DNA-probe molecules at functionalized electrodes via hybridization. Subsequent time resolved photoconductive sampling of the THz transmission identifies the binding state between probe and target DNA. Integrating neighbouring sensors on a chip, this technique can be extended to a parallel analysis of multiple DNA sequences. A clearly readable sensor response is obtained with less then 40 fmol of 20-mer single-stranded DNA molecules, indicating at least a sevenfold sensitivity increase compared to previous approaches.
159 citations
Cited by
More filters
Book•
15 May 2007
TL;DR: In this paper, the authors discuss the role of surface plasmon polaritons at metal/insulator interfaces and their application in the propagation of surfaceplasmon waveguides.
Abstract: Fundamentals of Plasmonics.- Electromagnetics of Metals.- Surface Plasmon Polaritons at Metal / Insulator Interfaces.- Excitation of Surface Plasmon Polaritons at Planar Interfaces.- Imaging Surface Plasmon Polariton Propagation.- Localized Surface Plasmons.- Electromagnetic Surface Modes at Low Frequencies.- Applications.- Plasmon Waveguides.- Transmission of Radiation Through Apertures and Films.- Enhancement of Emissive Processes and Nonlinearities.- Spectroscopy and Sensing.- Metamaterials and Imaging with Surface Plasmon Polaritons.- Concluding Remarks.
7,238 citations
TL;DR: An overview of the status of the terahertz technology, its uses and its future prospects are presented in this article, with a focus on the use of the waveband in a wide range of applications.
Abstract: Research into terahertz technology is now receiving increasing attention around the world, and devices exploiting this waveband are set to become increasingly important in a very diverse range of applications. Here, an overview of the status of the technology, its uses and its future prospects are presented.
5,512 citations
TL;DR: Terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules, as well as novel, higher-power terahertz sources.
Abstract: Terahertz spectroscopy systems use far-infrared radiation to extract molecular spectral information in an otherwise inaccessible portion of the electromagnetic spectrum. Materials research is an essential component of modern terahertz systems: novel, higher-power terahertz sources rely heavily on new materials such as quantum cascade structures. At the same time, terahertz spectroscopy and imaging provide a powerful tool for the characterization of a broad range of materials, including semiconductors and biomolecules.
2,673 citations
TL;DR: The research shows that NoC constitutes a unification of current trends of intrachip communication rather than an explicit new alternative.
Abstract: The scaling of microchip technologies has enabled large scale systems-on-chip (SoC). Network-on-chip (NoC) research addresses global communication in SoC, involving (i) a move from computation-centric to communication-centric design and (ii) the implementation of scalable communication structures. This survey presents a perspective on existing NoC research. We define the following abstractions: system, network adapter, network, and link to explain and structure the fundamental concepts. First, research relating to the actual network design is reviewed. Then system level design and modeling are discussed. We also evaluate performance analysis techniques. The research shows that NoC constitutes a unification of current trends of intrachip communication rather than an explicit new alternative.
1,720 citations
TL;DR: The terahertz time-domain spectroscopy (THz-TDS) as discussed by the authors is a new spectroscopic technique based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts.
Abstract: Over the past three decades a new spectroscopic technique with unique possibilities has emerged. Based on coherent and time-resolved detection of the electric field of ultrashort radiation bursts in the far-infrared, this technique has become known as terahertz time-domain spectroscopy (THz-TDS). In this review article the authors describe the technique in its various implementations for static and time-resolved spectroscopy, and illustrate the performance of the technique with recent examples from solid-state physics and physical chemistry as well as aqueous chemistry. Examples from other fields of research, where THz spectroscopic techniques have proven to be useful research tools, and the potential for industrial applications of THz spectroscopic and imaging techniques are discussed.
1,636 citations