Pyatkov, F., Khasminskaya, S., Fütterling, V., Fechner, R., Słowik, K., Ferrari, S., et al. (2016). Carbon nanotubes as exceptional electrically driven on-chip light sources. 2physics.com/2016/10.
Abstract: Carbon nanotubes (CNTs) belong to the most exciting objects of the nanoworld. Typically, around 1 nm in diameter and several microns long, these cylindrically shaped carbon-based structures exhibit a number of exceptional mechanical, electrical and optical characteristics [1]. In particular, they are promising ultra-small light sources for the next generation of optoelectronic devices, where electrical components are interconnected with photonic circuits.
Few years ago, we demonstrated that electically driven CNTs can serve as waveguide-integrated light sources [2]. Progress in the field of nanotube sorting, dielectrophoretical site-selective deposition and efficient light coupling into underlying substrate has made CNTs suitable for wafer-scale fabrication of active hybrid nanophotonic devices [2,3].
Recently we presented a nanotube-based waveguide integrated light emitters with tailored, exceptionally narrow emission-linewidths and short response times [4]. This allows conversion of electrical signals into well-defined optical signals directly within an optical waveguide, as required for future on-chip optical communication. Schematics and realization of this device is shown in Figure 1. The devices were manufactured by etching a photonic crystal waveguide into a dielectric layer following electron beam lithography. Photonic crystals are nanostructures that are also used by butterflies to give the impression of color on their wings. The same principle has been used in this study to select the color of light emitted by the CNT. The precise dimensions of the structure were numerically simulated to tailor the properties of the final device. Metallic contacts in the vicinity to the waveguide were fabricated to provide electrical access to CNT emitters. Finally, CNTs, sorted by structural and electronic properties, were deposited from a solution across the waveguide using dielectrophoresis, which is an electric-field-assisted deposition technique.
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Goltsman, G. N., Shcherbatenko, M. L., Lobanov, Y. V., Kovalyuk, V. V., Kahl, O., Ferrari, S., et al. (2016). Superconducting nanowire single photon detector for coherent detection of weak optical signals. In LPHYS'16 (pp. 1–2).
Abstract: Traditionally, photon detectors are operated in a direct detection mode counting incident photonswith a known quantum efficiency. This procedure allows one to detect weak sources of radiation but allthe information about its frequency is limited by the optical filtering/resonating structures used which arenot as precise as would be required for some practical applications. In this work we propose heterodynereceiver based on a photon counting mixer which would combine excellent sensitivity of a photon countingdetector and excellent spectral resolution given by the heterodyne technique. At present, Superconducting-Nanowire-Single-Photon-Detectors (SNSPDs) [1] are widely used in a variety of applications providing thebest possible combination of the sensitivity and speed. SNSPDs demonstrate lack of drawbacks like highdark count rate or autopulsing, which are common for traditional semiconductor-based photon detectors,such as avalanche photon diodes.In our study we have investigated SNSPD operated as a photon counting mixer. To fully understandits behavior in such a regime, we have utilized experimental setup based on a couple of distributedfeedback lasers irradiating at 1.5 micrometers, one of which is being the Local Oscillator (LO) and theother mimics the test signal [2]. The SNSPD was operated in the current mode and the bias currentwas slightly below of the critical current. Advantageously, we have found that LO power needed for anoptimal mixing is of the order of hundreds of femtowatts to a few picowatts, which is promising for manypractical applications, such as receiver matrices [3]. With use of the two lasers, one can observe thevoltage pulses produced by the detected photons, and the time distribution of the pulses reproduces thefrequency difference between the lasers, forming power response at the intermediate frequency which canbe captured by either an oscilloscope (an analysis of the pulse statistics is needed) or by an RF spectrumanalyzer. Photon-counting nature of the detector ensures quantum-limited sensitivity with respect to theoptical coupling achieved. In addition to the chip SNSPD with normal incidence coupling, we use thedetectors with a travelling wave geometry design [4]. In this case a NbN nanowire is placed on the topof a Si3N4 nanophotonic waveguide, thus increasing the efficient interaction length. For this reason it ispossible to achieve almost complete absorption of photons and reduce the detector footprint. This reducesthe noise of the device together with the expansion of the bandwidth. Integrated device scheme allowsus to measure the optical losses with high accuracy. Our approach is fully scalable and, along with alarge number of devices integrated on a single chip can be adapted to the mid and far IR ranges wherephoton-counting measurement may be beneficial as well [5].Acknowledgements: This work was supported in part by the Ministry of Education and Science of theRussian Federation, contract No. 14.B25.31.0007 and by RFBR grant No. 16-32-00465.
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Симонов, Н. О., Флоря, И. Н., Корнеева, Ю. П., Корнеев, А. А., & Гольцман, Г. Н. (2018). Однофотонный отклик в тонких сверхпроводящих MoNx пленках. In Сборн. науч. труд. VII международн. конф. по фотонике и информац. опт. (pp. 408–409).
Abstract: Продемонстрирован однофотонный отклик, при токе близком к критическому, в MoNx сверхпроводящих полосках шириной 70-104 нм. MoNx детекторы, имеющие коэффициент диффузии D≈0.32 см2/с и время электрон-фононного взаимодействия ηe-ph≈300 пс, достигают квантовой эффективности QE≈20% на длине волны λ=1550 нм. Возможность реализации однофотонного детектора в данном материале, подтверждает существующую теорию вихревого механизма возникновения фотоотклика в узких сверхпроводящих полосках.
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Золотов, Ф. И., Дивочий, А. В., Вахтомин, Ю. Б., Пентин, И. В., Морозов, П. В., Селезнев, В. А., et al. (2018). Применение тонких сверхпроводниковых пленок нитрида ванадия для изготовления счетчиков одиночных ИК-фотонов. In Сборн. науч. труд. VII международн. конф. по фотонике и информац. опт. (pp. 60–61).
Abstract: Получены первые результаты по применению сверхпроводниковых пленок нитрида ванадия (VN) для детекторов одиночных фотонов ИК-диапазона. Изучение сверхпроводниковых однофотонных детекторов (SSPD), изготовленных на основе ультратонких (~5 нм) пленок VN, показало возможность создания устройств с близкой к насыщению зависимостью квантовой эффективности от тока смещения детекторов в телекоммуникационном диапазоне длин волн. Также нами были исследованы кинетическая индуктивность изготовленных структур с различной длиной сверхпроводниковой полоски и времена релаксации электронов в тонких сверхпроводниковых пленках VN.
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Zolotov, P., Divochiy, A., Korneeva, Y., Vakhtomin, Y., Seleznev, V., & Smirnov, K. (2015). Capability investigation of superconducting single-photon detectors, optimized for 800–1200 nm spectrum range.
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Zolotov, P., Vakhtomin, Y., Divochiy, A., Morozov, P., Seleznev, V., & Smirnov, K. (2017). Development of fast and high-effective single-photon detector for spectrum range up to 2.3 μm. In Proc. SPBOPEN (pp. 439–440).
Abstract: We present the results of development and testing of the single-photon-counting system operating in the wide spectrum rane up to 2.3 mcm. We managed to increase system detection efficiency up to 60% in the range of 1.7-2.3 mcm optimisation of the fabrication methods of superconducting single-photon detectors and application of the single-mode fiber with enlarged core diameter.
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Kovalyuk, V., Ferrari, S., Kahl, O., Semenov, A., Lobanov, Y., Shcherbatenko, M., et al. (2017). Waveguide integrated superconducting single-photon detector for on-chip quantum and spectral photonic application.
Abstract: By adopting a travelling-wave geometry approach, integrated superconductor- nanophotonic devices were fabricated. The architecture consists of a superconducting NbN- nanowire atop of a silicon nitride (Si 3 N 4 ) nanophotonic waveguide. NbN-nanowire was operated as a single-photon counting detector, with up to 92% on-chip detection efficiency (OCDE), in the coherent mode, serving as a highly sensitive IR heterodyne mixer with spectral resolution (f/df) greater than 10^6 in C-band at 1550 nm wavelength.
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Zubkova, E., An, P., Kovalyuk, V., Korneev, A., & Goltsman, G. (2017). Integrated Bragg waveguides as an efficient optical notch filter on silicon nitride platform. In Proc. SPBOPEN (pp. 449–450).
Abstract: We modeled and fabricated integrated optical Bragg waveguides on a silicon nitride (Si3N4) platform. Transmission spectra of the integrated notch filter has been measured and attenuation at the desired wavelength of 1550 nm down to -43 dB was observed.
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Saveskul, N. A., Titova, N. A., Baeva, E. M., Semenov, A. V., Lubenchenko, A. V., Saha, S., et al. (2019). Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder. arXiv:1903.05009v3 [cond-mat.mtrl-sci].
Abstract: We analyze the evolution of the normal and superconducting electronic properties in epitaxial TiN films, characterized by high Ioffe-Regel parameter values, as a function of the film thickness. As the film thickness decreases, we observe an increase of in the residual resistivity, which becomes dominated by diffusive surface scattering for d≤20nm. At the same time, a substantial thickness-dependent reduction of the superconducting critical temperature is observed compared to the bulk TiN value. In such a high quality material films, this effect can be explained by a weak magnetic disorder residing in the surface layer with a characteristic magnetic defect density of ∼1012cm−2. Our results suggest that surface magnetic disorder is generally present in oxidized TiN films.
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Tovpeko, N. A., Trifonov, A. V., Semenov, A. V., Antipov, S. V., Kaurova, N. S., Titova, N. A., et al. (2019). Bandwidth performance of a THz normal metal TiN bolometer-mixer. In Proc. 30th Int. Symp. Space Terahertz Technol. (pp. 102–103).
Abstract: We report on the bandwidth performance of the normal metal TiN bolometer-mixer on top of an Al 2 O 3 substrate, which is capable to operate in a wide range of bath temperatures from 77 K – 300 K. The choice of the combination TiN / Al 2 O 3 is related to an advanced heat transport between the film and the substrate in this pair and the sufficient temperature coefficient of resistance. The data were taken at 132.5 – 145.5 GHz with two BWOs as a signal and an LO source. Measurements were taken on TiN films of different thickness starting from 20 nm down to 5 nm coupled into a spiral Au antenna, which improves matching of incoming radiation with the thin TiN fim. Our experiments demonstrate effective heat coupling from a TiN thin film to an Al 2 O 3 substrate (111) boosting gain bandwidth (GB) of TiN bolometer up to 6 GHz for 5 nm thin film. Current results indicate weak temperature dependence of GB on the bath temperature of the TiN bolometer. Theoretical estimations of GB performance meet with experimental data for 5 nm thin TiN films.
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