Records |
Author |
Elezov, M. S.; Shcherbatenko, M. L.; Sych, D. V.; Goltsman, G. N. |
Title |
Development of control method for an optimal quantum receiver |
Type |
Conference Article |
Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1695 |
Issue |
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Pages |
012126 |
Keywords |
Helstrom bound, SPD, single photon detector, below quantum limit |
Abstract |
We propose a method for optimal displacement controlling of an optimal quantum receiver for registrations a binary coherent signal. An optimal receiver is able to distinguish between two phase-modulated states of a coherent signal. The optimal receiver controlling method can be used later in practice in various physical implementations of the optimal receiver. |
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1742-6588 |
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Serial |
1264 |
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Author |
Shcherbatenko, M.; Elezov, M.; Sych, D.; Goltsman, G. N. |
Title |
Optimal fiber optic scheme for sub-SQL quantum receiver realization |
Type |
Conference Article |
Year |
2020 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1695 |
Issue |
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Pages |
012140 |
Keywords |
sub-SQL, below quantum limit, QL, system quantum limit, SQL |
Abstract |
Practical implementation of high-precision quantum measurements is an important problem in modern science. One of the main parts of the quantum receiver is the optical scheme. We developed and tested several optical circuits based on different types of interferometers, namely Sagnac-based scheme, Mach-Zehnder-based scheme, and Michelson-based scheme. All these schemes are assembled with optical fibers and fiber-optic components, since the fiber-optic implementation is closest to application in practical devices. Schemes were evaluated according to two main criteria: extinction and interference stability. On the basis of the obtained data, it can be concluded that the most suitable is the scheme based on the Mach-Zehnder interferometer. In continuous mode, we were able to obtain an interference extinction about 30 dB with acceptable temporal stability. |
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1742-6588 |
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no |
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1265 |
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Author |
Sidorova, M.; Semenov, Alexej D.; Hübers, H.-W.; Ilin, K.; Siegel, M.; Charaev, I.; Moshkova, M.; Kaurova, N.; Goltsman, G. N.; Zhang, X.; Schilling, A. |
Title |
Electron energy relaxation in disordered superconducting NbN films |
Type |
Journal Article |
Year |
2020 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
Volume |
102 |
Issue |
5 |
Pages |
054501 (1 to 15) |
Keywords |
NbN SSPD, SNSPD, HEB, bandwidth, relaxation time |
Abstract |
We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product qTl (qT is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14–30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/τe−ph∼Tn with the exponents n≈3.2–3.8. We found that in this temperature range τe−ph and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9–17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material. |
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2469-9950 |
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1266 |
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Ovchinnikov, O. V.; Perepelitsa, A. S.; Smirnov, M. S.; Latyshev, A. N.; Grevtseva, I. G.; Vasiliev, R. B.; Goltsman, G. N.; Vitukhnovsky, A. G. |
Title |
Luminescence of colloidal Ag2S/ZnS core/shell quantum dots capped with thioglycolic acid |
Type |
Journal Article |
Year |
2020 |
Publication |
J. Luminescence |
Abbreviated Journal |
J. Luminescence |
Volume |
220 |
Issue |
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Pages |
117008 (1 to 7) |
Keywords |
Ag2S QD, quantum dots |
Abstract |
The features of IR luminescence of colloidal AgS QDs passivated with thioglycolic acid (AgS/TGA) under the formation of AgS/ZnS/TGA core/shell QDs are considered. A 4.5-fold increase in the quantum yield of recombination IR luminescence within the band with a peak at 960 nm (1.29 eV), full width at half maximum of 250 nm (0.34 eV), and the Stokes shift with respect to the exciton absorption of 0.6 eV was found. The increase in the IR luminescence intensity of AgS/ZnS/TGA QDs is accompanied by an increase in the average luminescence lifetime from 2.9 ns to 14.3 ns, which is explained as “healing” of surface trap states during the formation of the ZnS shell. For the first time, the enhancement of the luminescence intensity photodegradation (hereinafter referred to as fatigue) was found during the formation of the AgS/ZnS/TGA core/shell QDs. The luminescence fatigue is irreversible. We conclude that the initial stage of photolysis of the AgS core QDs under laser irradiation plays a key role. Low-atomic photolytic clusters of silver formed on the AgS core QDs act as luminescence quenching centers and do not reveal structural transformations into AgS, provided that the clusters are not in contact with TGA. |
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0022-2313 |
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no |
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Serial |
1267 |
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Author |
Shcherbatenko, M. L.; Elezov, M. S.; Goltsman, G. N.; Sych, D. V. |
Title |
Sub-shot-noise-limited fiber-optic quantum receiver |
Type |
Journal Article |
Year |
2020 |
Publication |
Phys. Rev. A |
Abbreviated Journal |
Phys. Rev. A |
Volume |
101 |
Issue |
3 |
Pages |
032306 (1 to 5) |
Keywords |
SSPD mixer, SNSPD |
Abstract |
We experimentally demonstrate a quantum receiver based on the Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from standard fiber-optic elements and operates at a conventional telecom wavelength of 1.55 μm. The local oscillator and the signal are transmitted through different optical fibers, and the displaced signal is measured with a high-efficiency superconducting nanowire single-photon detector. We show the discrimination error rate is two times below that of a shot-noise-limited receiver with the same system detection efficiency. |
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2469-9926 |
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no |
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Serial |
1268 |
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Author |
Titova, N.; Gayduchenko, I. A.; Moskotin, M. V.; Fedorov, G. F.; Goltsman, G. N. |
Title |
Carbon nanotube based terahertz radiation detectors |
Type |
Conference Article |
Year |
2019 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1410 |
Issue |
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Pages |
012208 (1 to 5) |
Keywords |
carbon nanotubes, CNT |
Abstract |
In this paper, we study terahertz detectors based on single quasimetallic carbon nanotubes (CNT) with asymmetric contacts and different metal pairs. We demonstrate that, depending on the contact metallization of the device, various detection mechanisms are manifested. |
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1742-6588 |
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no |
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1270 |
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Author |
Manova, N. N.; Smirnov, E. O.; Korneeva, Yu. P.; Korneev, A. A.; Goltsman, G. N. |
Title |
Superconducting photon counter for nanophotonics applications |
Type |
Conference Article |
Year |
2019 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1410 |
Issue |
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Pages |
012147 (1 to 5) |
Keywords |
SSPD, SNSPD |
Abstract |
We develop large area superconducting single-photon detector SSPD with a micron-wide strip suitable for free-space coupling or packaging with multi-mode optical fibres. The detector sensitive area is 20 μm in diameter. In near infrared (1330 nm wavelength) our SSPD exhibits above 30% detection efficiency with low dark counts and 45 ps timing jitter. |
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1742-6588 |
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no |
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1271 |
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Author |
Baksheeva, K.; Vdovydchenko, A.; Gorshkov, K.; Ozhegov, R.; Kinev, N.; Koshelets, V.; Goltsman, G. |
Title |
Study of human skin radiation in the terahertz frequency range |
Type |
Conference Article |
Year |
2019 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1410 |
Issue |
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Pages |
012076 (1 to 5) |
Keywords |
SIS mixer, SIR, applications, medicine, sympathetic nervous system, SNS |
Abstract |
The radiation of human skin in the terahertz frequency range under the influence of mental stresses has been studied in the current work. An experimental setup for observation of changes in human skin radiation, which occur under the influence of psychological stresses, by means of a superconducting integrated receiver has been developed. More than 30 volunteers participate in these studies, which allows us to verify presence of correlation between the signals from the superconducting integrated terahertz receiver and other sensors that monitor human mental stress. |
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1742-6588 |
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no |
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1272 |
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Author |
Polyakova, M. I.; Florya, I. N.; Semenov, A. V.; Korneev, A. A.; Goltsman, G. N. |
Title |
Extracting hot-spot correlation length from SNSPD tomography data |
Type |
Conference Article |
Year |
2019 |
Publication |
J. Phys.: Conf. Ser. |
Abbreviated Journal |
J. Phys.: Conf. Ser. |
Volume |
1410 |
Issue |
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Pages |
012166 (1 to 4) |
Keywords |
SSPD, SNSPD, quantum detector tomography, QDT |
Abstract |
We present data of quantum detector tomography for the samples specifically optimized for this problem. Using this method, we take results of hot-spot correlation length of 17 ± 2 nm. |
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1742-6588 |
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no |
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1273 |
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Author |
Rasulova, G. K.; Pentin, I. V.; Goltsman, G. N. |
Title |
Terahertz emission from a weakly-coupled GaAs/AlGaAs superlattice biased into three different modes of current self-oscillations |
Type |
Journal Article |
Year |
2019 |
Publication |
AIP Advances |
Abbreviated Journal |
AIP Advances |
Volume |
9 |
Issue |
10 |
Pages |
105220 |
Keywords |
GaAs/AlGaAs superlattice, SL, NbN HEB |
Abstract |
Radio-frequency modulated terahertz (THz) emission power from weakly-coupled GaAs/AlGaAs superlattice (SL) has been increased by parallel connection of several SL mesas. Each SL mesa is a self-oscillator with its own oscillation frequency and mode. In coupled non-identical SL mesas biased at different voltages within the hysteresis loop the chaotic, quasiperiodic and frequency-locked modes of self-oscillations of current arise. THz emission was detected when three connected in parallel SL mesas were biased into the frequency-locked and quasiperiodic modes of self-oscillations of current, while in the chaotic mode of those it falls to the noise level. |
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2158-3226 |
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no |
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1274 |
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Author |
Elezov, M.; Ozhegov, R.; Goltsman, G.; Makarov, V. |
Title |
Countermeasure against bright-light attack on superconducting nanowire single-photon detector in quantum key distribution |
Type |
Journal Article |
Year |
2019 |
Publication |
Opt. Express |
Abbreviated Journal |
Opt. Express |
Volume |
27 |
Issue |
21 |
Pages |
30979-30988 |
Keywords |
SSPD, SNSPD |
Abstract |
We present an active anti-latching system for superconducting nanowire single-photon detectors. We experimentally test it against a bright-light attack, previously used to compromise security of quantum key distribution. Although our system detects continuous blinding, the detector is shown to be partially blindable and controllable by specially tailored sequences of bright pulses. Improvements to the countermeasure are suggested. |
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English |
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1094-4087 |
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PMID:31684339 |
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no |
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1275 |
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Tiulina, V.; Iomdina, E.; Goltsman, G.; Seliverstov, S.; Sianosyan, A.; Teplyakova, K.; Rusova, A.; Zaitsev, S.; Zernii, E.; Senin, I. |
Title |
UVB promotes the initiation of uveitic inflammatory and changes in thehydration of the cornea in vivo |
Type |
Miscellaneous |
Year |
2019 |
Publication |
FEBS Open Bio |
Abbreviated Journal |
FEBS Open Bio |
Volume |
9 |
Issue |
S1 |
Pages |
79 |
Keywords |
medicine; scheimpflug imaging; UVB; confocal microscopy; cornea; optical coherent tomography; rabbit eyes; terahertz radiation |
Abstract |
Recently, active research has been conducted in the field of terahertz (THz) scanning of human tissues for noninvasive determination of their hydration level, which haves hown high diagnostic efficiency of this technology in various pathological conditions. Recently, we have developed a laboratory model of the facility for monitoring the state of the water balance of the cornea using THz scanning in vivo, which opens up the possibility of applying this approach in ophthalmology. The aim of the work wasto compare the results of the THz scan of the cornea with its clinical changes using the example of an experimental model of the UV induced keratouveitis. Anexperimental study, which included a comprehensive assessment of clinical changes in the cornea of rabbits during keratouveitis induction, revealed a decrease in the stability of the tear film, pathological changes in the corneal epithelium and stroma, as well as its anatomical and optical parameters. Comparison of data obtained in the THz scan of the cornea with tears production, optical coherence tomography and confocal microscopy showed their consistency in all observation periods, which allows us to conclude that the developed laboratory setup works and the feasibility of further research to promote the corneal hydration evaluation technology in clinical practice. Acknowledgements: Research was funded by the RSF, grant number 161500255. |
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2211-5463 |
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Poster P-01-040 |
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no |
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1276 |
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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. |
Title |
Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder |
Type |
Miscellaneous |
Year |
2019 |
Publication |
arXiv |
Abbreviated Journal |
arXiv |
Volume |
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Issue |
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Pages |
1-10 |
Keywords |
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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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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. |
Title |
Bandwidth performance of a THz normal metal TiN bolometer-mixer |
Type |
Conference Article |
Year |
2019 |
Publication |
Proc. 30th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 30th Int. Symp. Space Terahertz Technol. |
Volume |
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Issue |
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Pages |
102-103 |
Keywords |
TiN normal metal bolometer, NMB |
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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1279 |
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Kovaluyk, V.; Lazarenko, P.; Kozyukhin, S.; An, P.; Prokhodtsov, A.; Goltsman, G.; Sherchenkov, A. |
Title |
Influence of the phase state of Ge2Sb2Te5 thin cover on the parameters of the optical waveguide structures |
Type |
Abstract |
Year |
2019 |
Publication |
Proc. Amorphous and Nanostructured Chalcogenides |
Abbreviated Journal |
Proc. Amorphous and Nanostructured Chalcogenides |
Volume |
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Pages |
47-48 |
Keywords |
optical waveguides |
Abstract |
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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