Impedance model for the polarization-dependent optical absorption of superconducting single-photon detectors

Driessen, E. F. C.; Braakman, Floris; Reiger, Elisabeth; Dorenbos, Sander N.; Zwiller, Val; Dood, M. J. A. de

doi:10.1051/epjap/2009087

Cited by 54 publications

(62 citation statements)

References 22 publications

(54 reference statements)

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“…Using this technique, we achieve selective illumination of either the sides or the middle of the wire, which we use to probe the intrinsic photodetection properties of our device on the nanoscale. However, it is well known that changing the polarization results in a change in overall optical absorption probability [16][17][18][19][20]. In order to correct for this effect, we must separate the probability that a photon is absorbed from the probability that an absorbed photon causes a detection event.…”

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confidence: 99%

Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

et al. 2015

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We probe the local detection efficiency in a nanowire superconducting single-photon detector along the cross-section of the wire with a spatial resolution of 10 nm. We experimentally find a strong variation in the local detection efficiency of the device. We demonstrate that this effect explains previously observed variations in NbN detector efficiency as function of device geometry.Nanowire superconducting single-photon detectors (SSPDs) consist of a superconducting wire of nanoscale cross-section [1], typically 4 nm by 100 nm. Photon detection occurs when a single quantum of light is absorbed and triggers a transition from the superconducting to the normal state. SSPDs have high efficiency, low jitter, low dark count rate and fast reset time [2], and are therefore a key technology for, among others, quantum key distribution Although progress has been made recently, the underlying physical mechanism responsible for photon detection on the nanoscale is still under active investigation. A combination of theory [6,7], experiments [8][9][10] and simulations [11,12] on NbN SSPDs indicates that the absorption of a photon destroys Cooper pairs in the superconductor and creates a localized cloud of quasiparticles that diverts current across the wire. This makes the wire susceptible to the entry of a superconducting vortex from the edge of the wire. Energy dissipation by this moving vortex drives the system to the normal state.An important and unexpected implication of this detection model is a nanoscale position variation in the photodetection properties of the device. The conditions at the entry point of the vortex determine the energy required for it to cross the wire. This causes photons absorbed close to the edge to have a local detection efficiency (LDE) [13] compared to photons absorbed in the center of the wire [12]. This effect has practical implications for the operation of SSPDs, since it represents a potential limitation of the detection efficiency. In addition, SSPDs have been proposed for nanoscale sensing, either in a near-field optical microscope configuration [14] or as a subwavelength multiphoton probe [15], where this effect would be of major importance for the properties of such a microscope. While this effect has been predicted theoretically, clear experimental evidence is missing. * renema@physics.leidenuniv.nlIn this work, we experimentally explore the nanoscale variations in the intrinsic response of the detector. We spatially resolve the LDE with a resolution of approximately 10 nm, better than λ/50, using far-field illumination only. We find that our results are qualitatively consistent with numerical simulations [11,12]. Our results provide excellent quantitative agreement with experiments that indicate a polarization dependence in the LDE that was hitherto not understood [16].The key technique used in this work is a differential polarization measurement that probes the IDE of the detector (see Figure 1). The technique is based on the fact that polarized light is absorbed preferentially in dif...

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Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

et al. 2015

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“…As can be seen in the figure, the internal detection efficiency of meandering wires is proportional to the fill fraction f , defined as the ratio of wire width w over the pitch p. Numerical calculations of the absorption profile of the various structures indeed show that the absorption distribution A ⊥, (x) is nearly identical to that of an isolated wire, resulting in an average absorption η that is proportional to f [27]. For a wavelength of 1550 nm the IDE of the SSPDs (slope of the dashed line) with parallel polarization is higher than that of SSPDs with perpendicular polarization, which is explained by the difference in absorption profile A ⊥, (x) for the two polarizations.…”

Section: A Optimal Response Of Meandering Wire Detectorsmentioning

confidence: 80%

Design of NbN superconducting nanowire single photon detectors with enhanced infrared photon detection efficiency

Wang

Renema

Engel

et al. 2017

Quantum Information and Measurement (QIM) 2017

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We optimize the design of NbN nanowire superconducting single photon detectors, using the recently discovered position dependent detection efficiency in these devices. This optimized design of meandering wire NbN detectors maximizes absorption at positions where photon detection is most efficient by altering the field distribution across the wire. In order to calculate the response of the detectors with different geometries, we use a monotonic local detection efficiency from a nanowire and optical absorption distribution via finite-different-time-domain simulations. The calculations predict a trade-off between average absorption and absorption at the edge, leading to a predicted optimal wire width close to 100 nm for 1550 nm wavelength, which drops to 50 nm wire width for 600 nm wavelength. The absorption at the edges can be enhanced by depositing a silicon nanowire on top of the superconducting nanowire, which improves both the total absorption efficiency as well as the internal detection efficiency of meandering wire structures. The proposed structure can be integrated in a relatively simple cavity structure to reach absorption efficiencies of 97% for perpendicular and 85% for parallel polarization.

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“…As can be seen in the figure, the internal detection efficiency of meandering wires is proportional to the fill fraction f, defined as the ratio of the wire width w over the pitch p. Numerical calculations of the absorption profile of the various structures indeed show that the absorption distribution A ⊥;∥ ðxÞ is nearly identical to that of an isolated wire, resulting in an average absorption η that is proportional to f [27]. For a wavelength of 1550 nm, the IDE of the SSPDs (the slope of the dashed line) with parallel polarization is higher than that of SSPDs with perpendicular polarization, which is explained by the difference in absorption profile A ⊥;∥ ðxÞ for the two polarizations.…”

Section: A Optimal Response Of Meandering Wire Detectorsmentioning

confidence: 82%

“…A known limitation of (meandering) wires is that the detection efficiency depends on the polarization of the incident light [26,27]; at normal incidence, absorption is more efficient when the electrical field vector of the light is aligned parallel to the wires, an effect governed by the boundary conditions on the edges of the nanowires. Recently, a design of a cavity-based structure was reported that tries to eliminate the polarization dependence and achieves up to 96% absorption efficiency for both polarizations [28], assuming that the internal detection efficiency is uniform across the nanowire.…”

Section: Local Detection Efficiencymentioning

confidence: 99%

Design of NbN Superconducting Nanowire Single-Photon Detectors with Enhanced Infrared Detection Efficiency

et al. 2017

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We optimize the design of NbN nanowire superconducting single-photon detectors using the recently discovered position-dependent detection efficiency in these devices. This optimized design of meandering wire NbN detectors maximizes absorption at positions where photon detection is most efficient by altering the field distribution across the wire. In order to calculate the response of the detectors with different geometries, we use a monotonic local detection efficiency from a nanowire and optical absorption distribution via finite-difference-time-domain simulations. The calculations predict a trade-off between average absorption and absorption at the edge, leading to a predicted optimal wire width close to 100 nm for a 1550-nm wavelength, which drops to a 50-nm wire width for a 600-nm wavelength. The absorption at the edges can be enhanced by depositing a silicon nanowire on top of the superconducting nanowire, which improves both the total absorption efficiency and the internal detection efficiency of meandering wire structures. The proposed structure can be integrated in a relatively simple cavity structure to reach absorption efficiencies of 97% for perpendicular and 85% for parallel polarization.

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Impedance model for the polarization-dependent optical absorption of superconducting single-photon detectors

Cited by 54 publications

References 22 publications

Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

Position-Dependent Local Detection Efficiency in a Nanowire Superconducting Single-Photon Detector

Design of NbN superconducting nanowire single photon detectors with enhanced infrared photon detection efficiency

Design of NbN Superconducting Nanowire Single-Photon Detectors with Enhanced Infrared Detection Efficiency

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