| Records |
| Author |
Casaburi, A.; Ejrnaes, M.; Quaranta, O.; Gaggero, A.; Mattioli, F.; Leoni, R.; Voronov, B.; Gol'tsman, G.; Lisitskiy, M.; Esposito, E.; Nappi, C.; Cristiano, R.; Pagano, S. |
| Title |
Experimental characterization of NbN nanowire optical detectors with parallel stripline configuration |
Type |
Conference Article |
| Year |
2008 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
| Volume |
97 |
Issue |
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Pages |
012265 (1 to 6) |
Keywords  |
NbN SSPD, SNSPD |
| Abstract |
We have developed a novel geometrical configuration for NbN-based superconducting single photon optical detector (SSPD) that achieves two goals: a much lower intrinsic impedance, and a consequently greater bandwidth, and a much larger signal amplitude compared to the standard meandered configuration. This has been obtained by implementing a properly designed parallel stripline structure where a cascade switching mechanism occurs when one of the striplines is hit by an optical photon. The overall switching occurs synchronously and in a very short time, giving rise to a strong and fast voltage pulse. The SSPD have been realized using state of the art NbN deposition technology and e-beam lithography. The strips are 100 nm wide and 5 μm long and have been realized with 4 nm NbN film on sapphire and Si substrate. We report on experimental characterization of such novel devices. The performances of the proposed novel type of SSPD are compared with standard SSPD design and results in terms of signal amplitude, risetime and effective detection area. |
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IOP Publishing |
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1742-6596 |
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8th European Conference on Applied Superconductivity (EUCAS 2007) |
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Serial |
1416 |
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| Author |
de Lara, D. Perez; Ejrnaes, M.; Casaburi, A.; Lisitskiy, M.; Cristiano, R.; Pagano, S.; Gaggero, A.; Leoni, R.; Golt’sman, G.; Voronov, B. |
| Title |
Feasibility investigation of NbN nanowires as detector in time-of-flight mass spectrometers for macromolecules of interest in biology (proteins) |
Type |
Journal Article |
| Year |
2008 |
Publication |
J. Low Temp. Phys. |
Abbreviated Journal |
J. Low Temp. Phys. |
| Volume |
151 |
Issue |
3-4 |
Pages |
771-776 |
| Keywords |
NbN SSPD, SNSPD, nanowires |
| Abstract |
We are investigating the possibility of using NbN nanowires as detectors in time-of-flight mass spectrometers for investigation of macromolecules of interest in biology (proteins). NbN nanowires could overcome the two major drawbacks encountered so far by cryogenic detectors, namely the low working temperature in the mK region and the slow temporal response. In fact, NbN nanowires can work at 5 K and the response time is at least a factor 10–100 better than that of other cryogenic detectors. We present a feasibility study based on a numerical code to calculate the response of a NbN nanowire. The parameter space is investigated at different energies from IR to macromolecules (i.e. from eV to keV) in order to understand if larger value of film thickness and width can be used for the keV energy region. We also present preliminary experimental results of irradiation with X-ray photons of NbN to simulate the effect of macromolecules of the same energy. |
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0022-2291 |
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no |
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Serial |
1410 |
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| Author |
Bryant, Garnett W.; García de Abajo, F. Javier; Aizpurua, Javier |
| Title |
Mapping the Plasmon Resonances of Metallic Nanoantennas |
Type |
Journal Article |
| Year |
2008 |
Publication |
Nano Letters |
Abbreviated Journal |
Nano Lett. |
| Volume |
5 |
Issue |
2 |
Pages |
631-636 |
| Keywords |
optical antennas |
| Abstract |
We study the light scattering and surface plasmon resonances of Au nanorods that are commonly used as optical nanoantennas in analogy to dipole radio antennas for chemical and biodetection field-enhanced spectroscopies and scanned-probe microscopies. With the use of the boundary element method, we calculate the nanorod near-field and far-field response to show how the nanorod shape and dimensions determine its optical response. A full mapping of the size (length and radius) dependence for Au nanorods is obtained. The dipolar plasmon resonance wavelength λ shows a nearly linear dependence on total rod length L out to the largest lengths that we study. However, L is always substantially less than λ/2, indicating the difference between optical nanoantennas and long-wavelength traditional λ/2 antennas. Although it is often assumed that the plasmon wavelength scales with the nanorod aspect ratio, we find that this scaling does not apply except in the extreme limit of very small, spherical nanoparticles. The plasmon response depends critically on both the rod length and radius. Large (500 nm) differences in resonance wavelength are found for structures with different sizes but with the same aspect ratio. In addition, the plasmon resonance deduced from the near-field enhancement can be significantly red-shifted due to retardation from the resonance in far-field scattering. Large differences in near-field and far-field response, together with the breakdown of the simple scaling law must be accounted for in the choice and design of metallic λ/2 nanoantennas. We provide a general, practical map of the resonances for use in locating the desired response for gold nanoantennas. |
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RPLAB @ gujma @ |
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737 |
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| Author |
Saynak, UÄŸur |
| Title |
Novel rectangular spiral antennas |
Type |
Manuscript |
| Year |
2008 |
Publication |
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Pages |
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| Keywords |
optical antennas |
| Abstract |
Round spiral antennas are generally designed by using Archimedean spiral geometries which have linear growth rates. To obtain smaller antennas with nearly the same performance, square spiral Archimedean geometries are also widely used instead. In this study, novel square antennas are proposed, designed and examined. At first two similar but different approaches are employed to design new antennas by considering the design procedure used to obtain log-periodic antennas. Then, the performance of these antennas is improved by considering another property of log-periodic antennas. Simulations are performed by using two different numerical methods which are Finite Difference Time Domain Method (FDTD) and Method of Moments (MoM). The results obtained from the simulations are compared with those of the Archimedean spiral antennas in terms of the frequency dependency of fundamental antenna parameters such as antenna gain and radiation pattern. The simulation results are compared with the ones obtained from the experimental study. |
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RPLAB @ gujma @ |
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750 |
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Tang, Liang; Kocabas, Sukru Ekin; Latif, Salman; Okyay, Ali K.; Ly-Gagnon, Dany-Sebastien; Saraswat, Krishna C.; Miller, David A. B. |
| Title |
Nanometre-scale germanium photodetector enhanced by a near-infrared dipole antenna |
Type |
Journal Article |
| Year |
2008 |
Publication |
Nature Photonics |
Abbreviated Journal |
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| Volume |
2 |
Issue |
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Pages |
226-229 |
| Keywords |
optical antennas |
| Abstract |
A critical challenge for the convergence of optics and electronics is that the micrometre scale of optics is significantly larger than the nanometre scale of modern electronic devices. In the conversion from photons to electrons by photodetectors, this size incompatibility often leads to substantial penalties in power dissipation, area, latency and noise. A photodetector can be made smaller by using a subwavelength active region; however, this can result in very low responsivity because of the diffraction limit of the light. Here we exploit the idea of a half-wave Hertz dipole antenna (length approx 380 nm) from radio waves, but at near-infrared wavelengths (length approx 1.3 microm), to concentrate radiation into a nanometre-scale germanium photodetector. This gives a polarization contrast of a factor of 20 in the resulting photocurrent in the subwavelength germanium element, which has an active volume of 0.00072 microm3, a size that is two orders of magnitude smaller than previously demonstrated detectors at such wavelengths. |
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858 |
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