Kawano Y, Ishibashi K. An on-chip near-field terahertz probe and detector. Nature Photon. 2008;2(10):618–21.
Abstract: The advantageous properties of terahertz waves, such as their transmission through objects opaque to visible light, are attracting attention for imaging applications. A promising approach for achieving high spatial resolution is the use of near-field imaging. Although this method has been well established in the visible and microwave regions, it is challenging to perform in the terahertz region. In the terahertz techniques investigated to date, detectors have been located remotely from the probe, which degrades sensitivity, and the influence of far-field waves is unavoidable. Here we present a new integrated detection device for terahertz near-field imaging in which all the necessary detection components — an aperture, a probe and a terahertz detector — are integrated on one semiconductor chip, which is cryogenically cooled. This scheme allows highly sensitive, high-resolution detection of the evanescent field alone and promises new capabilities for high-resolution terahertz imaging.
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Anant V, Kerman AJ, Dauler EA, Yang JKW, Rosfjord Kine M, Berggren KK. Optical properties of superconducting nanowire single-photon detectors. Opt Express. 2008;16(14):10750.
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Mohan N, Minaeva O, Gol'tsman GN, Nasr MB, Saleh BE, Sergienko AV, et al. Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors. Opt Express. 2008;16(22):18118–30.
Abstract: We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.
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Nasr MB, Minaeva O, Goltsman GN, Sergienko AV, Saleh BE, Teich MC. Submicron axial resolution in an ultrabroadband two-photon interferometer using superconducting single-photon detectors. Opt Express. 2008;16(19):15104–8.
Abstract: We generate ultrabroadband biphotons via the process of spontaneous parametric down-conversion in a quasi-phase-matched nonlinear grating that has a linearly chirped poling period. Using these biphotons in conjunction with superconducting single-photon detectors (SSPDs), we measure the narrowest Hong-Ou-Mandel dip to date in a two-photon interferometer, having a full width at half maximum (FWHM) of approximately 5.7 fsec. This FWHM corresponds to a quantum optical coherence tomography (QOCT) axial resolution of 0.85 µm. Our results indicate that a high flux of nonoverlapping biphotons may be generated, as required in many applications of nonclassical light.
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Shah N, Pekker D, Goldbart PM. Inherent stochasticity of superconductor-resistor switching behavior in nanowires. Phys Rev Lett. 2008;101:207001(1 to 4).
Abstract: We study the stochastic dynamics of superconductive-resistive switching in hysteretic current-biased superconducting nanowires undergoing phase-slip fluctuations. We evaluate the mean switching time using the master-equation formalism, and hence obtain the distribution of switching currents. We find that as the temperature is reduced this distribution initially broadens; only at lower temperatures does it show the narrowing with cooling naively expected for phase slips that are thermally activated. We also find that although several phase-slip events are generally necessary to induce switching, there is an experimentally accessible regime of temperatures and currents for which just one single phase-slip event is sufficient to induce switching, via the local heating it causes.
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