| Records |
| Author |
Bakhvalova, T.; Belkin, M. E.; Kovalyuk, V. V.; Prokhodtcov, A. I.; Goltsman, G. N.; Sigov, A. S. |
| Title |
Studying key principles for design and fabrication of silicon photonic-based beamforming networks |
Type |
Conference Article |
| Year |
2019 |
Publication |
PIERS-Spring |
Abbreviated Journal |
PIERS-Spring |
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Issue |
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Pages |
745-751 |
| Keywords |
silicon photonics, TriPleX platform |
| Abstract |
In the paper, we address key principles for computer-aided design and fabrication of silicon-photonics-based optical beamforming network selecting the optimal approach by simulation and experimental results. To clarify the consideration, the study is conducted on the example of a widely used binary switchable silicon-nitride optical beamforming network based on TriPleX platform. Comparison of simulation results and experimental studies of the prototype shows that the relative error due to technological imperfections does not exceed 3%. According to the estimation, such an error introduces insignificant distortion in the radiation pattern of the referred antenna array. |
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9017646 |
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1186 |
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Trifonov, A.; Tong, C.-Y. E.; Lobanov, Y.; Kaurova, N.; Blundell, R.; Goltsman, G. |
| Title |
Gap frequency and photon absorption in a hot electron bolometer |
Type |
Conference Article |
| Year |
2016 |
Publication |
Proc. 27th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 27th Int. Symp. Space Terahertz Technol. |
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121 |
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NbN HEB; Si membrane |
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The superconducting energy gap is a crucial parameter of a superconductor when used in mixing applications. In the case of the SIS mixer, the mixing process is efficient for frequencies below the energy gap, whereas, in the case of the HEB mixer, the mixing process is most efficient at frequencies above the gap, where photon absorption takes place more readily. We have investigated the photon absorption phenomenon around the gap frequency of HEB mixers based on NbN films deposited on silicon membranes. Apart from studying the pumped I-V curves of HEB devices, we have also probed them with microwave radiation, as previously described [1]. At frequencies far below the gap frequency, the pumped I-V curves show abrupt switching between the superconducting and resistive states. For the NbN HEB mixers we tested, which have critical temperatures of ~9 K, this is true for frequencies below about 400 GHz. As the pump frequency is increased beyond 400 GHz, the resistive state extends towards zero bias and at some point a small region of negative differential resistance appears close to zero bias. In this region, the microwave probe reveals that the device impedance is changing randomly with time. As the pump frequency is further increased, this random impedance change develops into relaxation oscillations, which can be observed by the demodulation of the reflected microwave probe. Initially, these oscillations take the form of several frequencies grouped together under an envelope. As we approach the gap frequency, the multiple frequency relaxation oscillations coalesce into a single frequency of a few MHz. The resultant square-wave nature of the oscillation is a clear indication that the device is in a bi-stable state, switching between the superconducting and normal state. Above the gap frequency, it is possible to obtain a pumped I-V curve with no negative differential resistance above a threshold pumping level. Below this pumping level, the device demonstrates bi-stability, and regular relaxation oscillation at a few MHz is observed as a function of pump power. The threshold pumping level is clearly related to the amount of power absorbed by the device and its phonon cooling. From the above experiment, we can derive the gap frequency of the NbN film, which is 585 GHz for our 6 μm thin silicon membrane-based device. We also confirm that the HEB mixer is not an efficient photon absorber for radiation below the gap frequency. 1. A. Trifonov et al., “Probing the stability of HEB mixers with microwave injection”, IEEE Trans. Appl. Supercond., vol. 25, no. 3, June 2015. |
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1204 |
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Kahl, O.; Ferrari, S.; Kovalyuk, V.; Vetter, A.; Lewes-Malandrakis, G.; Nebel, C.; Korneev, A.; Goltsman, G.; Pernice, W. |
| Title |
Spectrally multiplexed single-photon detection with hybrid superconducting nanophotonic circuits: supplementary material |
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Miscellaneous |
| Year |
2017 |
Publication |
Optica |
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1-9 |
| Keywords |
Quantum detectors; Spectrometers and spectroscopic instrumentation; Nanophotonics and photonic crystals; Fluorescence correlation spectroscopy; Fluorescence resonance energy transfer; Fluorescence spectroscopy; Imaging techniques; Optical components; Quantum key distribution |
| Abstract |
This document provides supplementary information to “Spectrally multiplexed single-photon detection with hybrid superconducting nanophotonic circuits", DOI:10.1364/optica.4.000557. Here we detail the on-chip spectrometer design, its characterization and the experimental setup we used. In addition, we present a detailed report concerning the characterization of the superconducting nanowire single photon detectors. In the final sections, we describe sample preparation and characterization of the nanodiamonds containing silicon vacancy color centers. |
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Osa |
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no |
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Kahl:17 |
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1218 |
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Goltsman, G. N.; Shcherbatenko, M. L.; Lobanov, Y. V.; Kovalyuk, V. V.; Kahl, O.; Ferrari, S.; Korneev, A.; Pernice, W. H. P. |
| Title |
Superconducting nanowire single photon detector for coherent detection of weak optical signals |
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Abstract |
| Year |
2016 |
Publication |
LPHYS'16 |
Abbreviated Journal |
LPHYS'16 |
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1-2 |
| Keywords |
SSPD, SNSPD |
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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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1220 |
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Kovalyuk, V.; Ferrari, S.; Kahl, O.; Semenov, A.; Lobanov, Yu; Shcherbatenko, M.; Korneev, A; Pernice, W.; Goltsman, G. |
| Title |
Waveguide integrated superconducting single-photon detector for on-chip quantum and spectral photonic application |
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Conference Volume |
| Year |
2017 |
Publication |
Proc. SPBOPEN |
Abbreviated Journal |
Proc. SPBOPEN |
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Pages |
421-422 |
| Keywords |
waveguide, SSPD, SNSPD |
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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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St. Petersburg, Russia |
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Duplicated as 1140 |
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no |
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1256 |
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Zubkova, E.; An, P.; Kovalyuk, V.; Korneev, A.; Goltsman, G. |
| Title |
Integrated Bragg waveguides as an efficient optical notch filter on silicon nitride platform |
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Conference Article |
| Year |
2017 |
Publication |
Proc. SPBOPEN |
Abbreviated Journal |
Proc. SPBOPEN |
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Issue |
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Pages |
449-450 |
| Keywords |
Bragg waveguides |
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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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St. Petersburg, Russia |
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Duplicated as 1141 |
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1257 |
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Baksheeva, K.; Ozhegov, R.; Goltsman, G.; Kinev, N.; Koshelets, V.; Kochnev, A.; Betzalel, N.; Puzenko, A.; Ben Ishai, P.; Feldman, Y. |
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The sub THz emission of the human body under physiological stress |
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Journal Article |
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2021 |
Publication |
IEEE Trans. Terahertz Sci. Technol. |
Abbreviated Journal |
IEEE Trans. Terahertz Sci. Technol. |
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skin sub-THz emission, medicine |
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We present evidence that in the sub-THz frequency band, human skin can be considered as an electromagnetic bio-metamaterial, in that its natural emission is a product of skin tissue geometry and embedded structures. Radiometry was performed on 32 human subjects from 480 to 700 GHz. Concurrently, the subjects were exposed to stress, while heart pulse rate (PS) and galvanic skin response (GSR) were also measured. The results are substantially different from the expected black body radiation signal of the skin surface. PS and GSR correlate to the emissivity. Using a simulation model for the skin, we find that the sweat duct is a critical element. The simulated frequency spectra qualitatively match the measured emission spectra and show that our sub-THz emission is modulated by our level of mental stress. This opens avenues for the remote monitoring of the human state. |
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no |
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9380570 |
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1259 |
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Lobanov, Y. V.; Vakhtomin, Y. B.; Pentin, I. V.; Rosental, V. A.; Smirnov, K. V.; Goltsman, G. N.; Volkov, O. Y.; Dyuzhikov, I. N.; Galiev, R. R.; Ponomarev, D. S.; Khabibullin, R. A. |
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Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser |
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Journal Article |
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2021 |
Publication |
Optical Engineering |
Abbreviated Journal |
Optical Engineering |
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60 |
Issue |
8 |
Pages |
1-8 |
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HEB, terahertz pulse generation, terahertz pulse detection, QCL, quantum cascade laser, superconducting hot electron bolometer |
| Abstract |
Quantum cascade lasers (QCL) are widely adopted as prominent and easy-to-use solid-state sources of terahertz radiation. Yet some applications require generation and detection of very sharp and narrow terahertz-range pulses with a specific spectral composition. We have studied time-resolved light-current (L–I) characteristics of multimode THz QCL operated with a fast ramp of the injection current. Detection of THz pulses was carried out using an NbN superconducting hot-electron bolometer with the time constant of the order of 1 ns while the laser bias current was swept during a single driving pulse. A nonmonotonic behavior of the L–I characteristic with several visually separated subpeaks was found. This behavior is associated with the mode competition in THz QCL cavity, which we confirm by L–I measurements with use of an external Fabry–Perot interferometer for a discrete mode selection. We also have demonstrated the possibility to control the L–I shape with suppression of one of the subpeaks by simply adjusting the off-axis parabolic mirror for optimal optical alignment for one of the laser modes. The developed technique paves the way for rapid characterization of pulsed THz QCLs for further studies of the possibilities of using this approach in remote sensing. |
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Spie |
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10.1117/1.Oe.60.8.082019 |
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1260 |
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Matyushkin, Y.; Kaurova, N.; Voronov, B.; Goltsman, G.; Fedorov, G. |
| Title |
On chip carbon nanotube tunneling spectroscopy |
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Journal Article |
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2020 |
Publication |
Fullerenes, Nanotubes and Carbon Nanostructures |
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28 |
Issue |
1 |
Pages |
50-53 |
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carbon nanotubes, CNT, scanning tunneling microscope, STM |
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We report an experimental study of the band structure of individual carbon nanotubes (SCNTs) based on investigation of the tunneling density of states, i.e. tunneling spectroscopy. A common approach to this task is to use a scanning tunneling microscope (STM). However, this approach has a number of drawbacks, to overcome which, we propose another method – tunneling spectroscopy of SCNTs on a chip using a tunneling contact. This method is simpler, cheaper and technologically advanced than the STM. Fabrication of a tunnel contact can be easily integrated into any technological route, therefore, a tunnel contact can be used, for example, as an additional tool in characterizing any devices based on individual CNTs. In this paper we demonstrate a simple technological procedure that results in fabrication of good-quality tunneling contacts to carbon nanotubes. |
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Taylor & Francis |
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doi:10.1080/1536383X.2019.1671365 |
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1269 |
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Antipov, S.; Trifonov, A.; Krause, S.; Meledin, D.; Kaurova, N.; Rudzinski, M.; Desmaris, V.; Belitsky, V.; Goltsman, G. |
| Title |
Improved bandwidth of a 2 THz hot-electron bolometer heterodyne mixer fabricated on sapphire with a GaN buffer layer |
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Journal Article |
| Year |
2019 |
Publication |
Supercond. Sci. Technol. |
Abbreviated Journal |
Supercond. Sci. Technol. |
| Volume |
32 |
Issue |
7 |
Pages |
075003 |
| Keywords |
NbN HEB mixer, GaN buffer layer, sapphire substrate |
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We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer. |
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IOP Publishing |
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Antipov_2019 |
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1277 |
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Saveskul, N. A.; Titova, N. A.; Baeva, E. M.; Semenov, A. V.; Lubenchenko, A. V.; Saha, S.; Reddy, H.; Bogdanov, S. I.; Marinero, E. E.; Shalaev, V. M.; Boltasseva, A.; Khrapai, V. S.; Kardakova, A. I.; Goltsman, G. N. |
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Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder |
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Miscellaneous |
| Year |
2019 |
Publication |
arXiv |
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arXiv |
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1-10 |
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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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1278 |
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Tovpeko, N. A.; Trifonov, A. V.; Semenov, A. V.; Antipov, S. V.; Kaurova, N. S.; Titova, N. A.; Goltsman, G. N. |
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Bandwidth performance of a THz normal metal TiN bolometer-mixer |
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Conference Article |
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2019 |
Publication |
Proc. 30th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 30th Int. Symp. Space Terahertz Technol. |
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102-103 |
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TiN normal metal bolometer, NMB |
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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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1279 |
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Kovaluyk, V.; Lazarenko, P.; Kozyukhin, S.; An, P.; Prokhodtsov, A.; Goltsman, G.; Sherchenkov, A. |
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Influence of the phase state of Ge2Sb2Te5 thin cover on the parameters of the optical waveguide structures |
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Abstract |
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2019 |
Publication |
Proc. Amorphous and Nanostructured Chalcogenides |
Abbreviated Journal |
Proc. Amorphous and Nanostructured Chalcogenides |
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47-48 |
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optical waveguides |
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The fast switching time of Ge-Sb-Te thin films between amorphous and crystalline states initiated by laser beam as well as significant change of their optical properties and the preservation of metastable states for tens of years open wide perspectives for the application of these materials to fully optical devices [1], including high-speed optical memory [2]. Here we study optical properties of the Ge2Sb2Te5 (GST225) thin films integrated with on-chip silicon nitride O-ring resonator. The rib waveguide of the resonator was formed the first stage of e-beam lithography and subsequent reactive-ion etching. We used the second stage of e-beam lithography combining with lift-off method for the formation of GST225 active region on the resonator ring surface. The amorphous GST225 thin films were prepared by magnetron sputtering, and were capped by thin silicon oxide on their tops. The length of the GST225 active region varied from 0.1 to 20 μ m. Crystallization of amorphous thin films was carried out at the temperature of 400 °C for 30 minutes. Auger electron spectroscopy and transmission electron microscopy were used for studying composition and structure of investigated GST225thin films, respectively. It was observed that crystallization of amorphous GST225 film lead to a decrease of the optical power, transmitted through the waveguide. Comparison of the optical transmittance of O-ring resonators before and after the GST225 deposition allowed to identify the change in the Q-factor and the wavelength peak shift. This can be explained by the differences of the complex refractive indexes of GST225 thin films in the amorphous and crystalline states. From the measurement data, the GST225 effective refractive index was extracted depending on the ring waveguide width of the resonator for a telecommunication wavelength of 1550 nm. |
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Technical University of Moldova |
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1281 |
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| Author |
Goltsman, G. |
| Title |
Quantum-photonic integrated circuits |
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Conference Article |
| Year |
2019 |
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Proc. IWQO |
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Proc. IWQO |
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22-23 |
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WSSPD, waveguide SSPD, SNSPD, quantum optics, integrated optics, superconducting nanowire single-photon detector |
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We show the design, a history of development as well as the most successful and promising approaches for QPICs realization based on hybrid nanophotonic-superconducting devices, where one of the key elements of such a circuit is a waveguide integrated superconducting single-photon detector (WSSPD). The potential of integration with fluorescent molecules is discussed also. |
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1287 |
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Fedorov, G.; Gayduchenko, I.; Titova, N.; Moskotin, M.; Obraztsova, E.; Rybin, M.; Goltsman, G. |
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Graphene-based lateral Schottky diodes for detecting terahertz radiation |
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Conference Article |
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2018 |
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Proc. Optical Sensing and Detection V |
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Proc. Optical Sensing and Detection V |
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10680 |
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30-39 |
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graphene, terahertz radiation, detectors, Schottky diodes, carbon nanotubes, plasma waves |
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Demand for efficient terahertz radiation detectors resulted in intensive study of the carbon nanostructures as possible solution for that problem. In this work we investigate the response to sub-terahertz radiation of graphene field effect transistors of two configurations. The devices of the first type are based on single layer CVD graphene with asymmetric source and drain (vanadium and gold) contacts and operate as lateral Schottky diodes (LSD). The devices of the second type are made in so-called Dyakonov-Shur configuration in which the radiation is coupled through a spiral antenna to source and top electrodes. We show that at 300 K the LSD detector exhibit the room-temperature responsivity from R = 15 V/W at f= 129 GHz to R = 3 V/W at f = 450 GHz. The DS detector responsivity is markedly lower (2 V/W) and practically frequency independent in the investigated range. We find that at low temperatures (77K) the graphene lateral Schottky diodes responsivity rises with the increasing frequency of the incident sub-THz radiation. We interpret this result as a manifestation of a plasmonic effect in the devices with the relatively long plasmonic wavelengths. The obtained data allows for determination of the most promising directions of development of the technology of nanocarbon structures for the detection of THz radiation. |
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Spie |
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Berghmans, F.; Mignani, A.G. |
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10.1117/12.2307020 |
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1306 |
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