| Records |
| Author |
Iomdina, E. N.; Seliverstov, S. V.; Teplyakova, K. O.; Jani, E. V.; Pozdniakova, V. V.; Polyakova, O. N.; Goltsman, G. N. |
| Title |
Terahertz scanning of the rabbit cornea with experimental UVB-induced damage: in vivo assessment of hydration and its verification |
Type |
Journal Article |
| Year |
2021 |
Publication |
J. Biomed. Opt. |
Abbreviated Journal |
J. Biomed. Opt. |
| Volume |
26 |
Issue |
4 |
Pages |
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| Keywords |
medicine; scheimpflug imaging; UVB; confocal microscopy; cornea; optical coherent tomography; rabbit eyes; terahertz radiation |
Abstract  |
SIGNIFICANCE: Water content plays a vital role in the normally functioning visual system; even a minor disruption in the water balance may be harmful. Today, no direct method exists for corneal hydration assessment, while it could be instrumental in early diagnosis and control of a variety of eye diseases. The use of terahertz (THz) radiation, which is highly sensitive to water content, appears to be very promising. AIM: To find out how THz scanning parameters of corneal tissue measured by an experimental setup, specially developed for in vivo contactless estimations of corneal reflectivity coefficient (RC), are related to pathological changes in the cornea caused by B-band ultraviolet (UVB) exposure. APPROACH: The setup was tested on rabbit eyes in vivo. Prior to the course of UVB irradiation and 1, 5, and 30 days after it, a series of examinations of the corneal state was made. At the same time points, corneal hydration was assessed by measuring RC. RESULTS: The obtained data confirmed the negative impact of UVB irradiation course on the intensity of tear production and on the corneal thickness and optical parameters. A significant (1.8 times) increase in RC on the 5th day after the irradiation course, followed by a slight decrease on the 30th day after it was revealed. The RC increase measured 5 days after the UVB irradiation course generally corresponded to the increase (by a factor of 1.3) of tear production. RC increase occurred with the corneal edema, which was manifested by corneal thickening (by 18.2% in the middle area and 17.6% in corneal periphery) and an increased volume of corneal tissue (by 17.6%). CONCLUSIONS: Our results demonstrate that the proposed approach can be used for in vivo contactless estimation of the reflectivity of rabbit cornea in the THz range and, thereby, of cornea hydration. |
| Address |
National Research University Higher School of Economics, Moscow Institute of Electronics and Mathema, Russia |
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English |
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1083-3668 |
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PMID:33834684; PMCID:PMC8027227 |
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no |
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Serial |
1258 |
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| Author |
Okunev, O.; Chulkova, G.; Milostnaya, I.; Antipov, A.; Smirnov, K.; Morozov, D.; Korneev, A.; Voronov, B.; Gol’tsman, G.; Stysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Gorska, M.; Pearlman, A.; Cross, A.; Kitaygorsky, J.; Sobolewski, R. |
| Title |
Registration of infrared single photons by a two-channel receiver based on fiber-coupled superconducting single-photon detectors |
Type |
Conference Article |
| Year |
2005 |
Publication |
Proc. 2-nd CAOL |
Abbreviated Journal |
Proc. 2-nd CAOL |
| Volume |
2 |
Issue |
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Pages |
282-285 |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
Single-photon detectors (SPDs) are the foundation of all quantum communications (QC) protocols. Among different classes of SPDs currently studied, NbN superconducting SPDs (SSPDs) are established as the best devices for ultrafast counting of single photons in the infrared (IR) wavelength range. The SSPDs are nanostructured, 100 /spl mu/m/sup 2/ in total area, superconducting meanders, patterned by electron lithography in ultra-thin NbN films. Their operation has been explained within a phenomenological hot-electron photoresponse model. We present the design and performance of a novel, two-channel SPD receiver, based on two fiber-coupled NbN SSPDs. The receivers have been developed for fiber-based QC systems, operational at 1.3 /spl mu/m and 1.55 /spl mu/m telecommunication wavelengths. They operate in the temperature range from 4.2 K to 2 K, in which the NbN SSPDs exhibit their best performance. The receiver unit has been designed as a cryostat insert, placed inside a standard liquid-helium storage dewar. The input of the receiver consists of a pair of single-mode optical fibers, equipped with the standard FC connectors and kept at room temperature. Coupling between the SSPD and the fiber is achieved using a specially designed, precise micromechanical holder that places the fiber directly on top of the SSPD nanostructure. Our receivers achieve the quantum efficiency of up to 7% for near-IR photons, with the coupling efficiency of about 30%. The response time was measured to be <300 ps and it was limited by our read-out electronics. The jitter of fiber-coupled SSPDs is <35 ps and their dark-count rate is below 1 s/sup -1/. The presented performance parameters show that our single-photon receivers are fully applicable for quantum-correlation-type QC systems, including practical quantum cryptography. |
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Conference |
Second International Conference on Advanced Optoelectronics and Lasers |
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no |
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Serial |
1462 |
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| Author |
Okunev, O.; Chulkova, G.; Milostnaya, I.; Antipov, A.; Smirnov, K.; Morozov, D.; Korneev, A.; Voronov, B.; Gol’tsman, G.; Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Górska, M.; Pearlman, A.; Cross, A.; Kitaygorsky, J.; Sobolewski, R. |
| Title |
Registration of infrared single photons by a two-channel receiver based on fiber-coupled superconducting single-photon detectors |
Type |
Conference Article |
| Year |
2008 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
| Volume |
7009 |
Issue |
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Pages |
70090V (1 to 8) |
| Keywords |
SSPD, SNSPD, single-photon detectors, superconductors, superconducting nanost |
| Abstract |
Single-photon detectors (SPDs) are the foundation of all quantum communications (QC) protocols. Among different classes of SPDs currently studied, NbN superconducting SPDs (SSPDs) are established as the best devices for ultrafast counting of single photons in the infrared (IR) wavelength range. The SSPDs are nanostructured, 100 μm2 in total area, superconducting meanders, patterned by electron lithography in ultra-thin NbN films. Their operation has been explained within a phenomenological hot-electron photoresponse model. We present the design and performance of a novel, two-channel SPD receiver, based on two fiber-coupled NbN SSPDs. The receivers have been developed for fiber-based QC systems, operational at 1.3 μm and 1.55 μm telecommunication wavelengths. They operate in the temperature range from 4.2 K to 2 K, in which the NbN SSPDs exhibit their best performance. The receiver unit has been designed as a cryostat insert, placed inside a standard liquid-heliumstorage dewar. The input of the receiver consists of a pair of single-mode optical fibers, equipped with the standard FC connectors and kept at room temperature. Coupling between the SSPD and the fiber is achieved using a specially designed, precise micromechanical holder that places the fiber directly on top of the SSPD nanostructure. Our receivers achieve the quantum efficiency of up to 7% for near-IR photons, with the coupling efficiency of about 30%. The response time was measured to be < 1.5 ns and it was limited by our read-out electronics. The jitter of fiber-coupled SSPDs is < 35 ps and their dark-count rate is below 1s-1. The presented performance parameters show that our single-photon receivers are fully applicable for quantum correlation-type QC systems, including practical quantum cryptography. |
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Thesis |
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| Publisher |
SPIE |
Place of Publication |
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Editor |
Sukhoivanov, I.A.; Svich, V.A.; Shmaliy, Y.S. |
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Approved |
no |
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Serial |
1413 |
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Antipov, A. V.; Seleznev, V. A.; Vakhtomin, Y. B.; Morozov, P. V.; Vasilev, D. D.; Malevannaya, E. I.; Moiseev, K. M.; Smirnov, K. |
| Title |
Investigation of WSi and NbN superconducting single-photon detectors in mid-IR range |
Type |
Conference Article |
| Year |
2020 |
Publication |
IOP Conf. Ser.: Mater. Sci. Eng. |
Abbreviated Journal |
IOP Conf. Ser.: Mater. Sci. Eng. |
| Volume |
781 |
Issue |
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Pages |
012011 (1 to 5) |
| Keywords |
WSi, NbN SSPD, SNSPD |
| Abstract |
Spectral characteristics of WSi and NbN superconducting single-photon detectors with different surface resistance and width of nanowire strips have been investigated in the wavelength range of 1.3-2.5 μm. WSi structures with narrower strips demonstrated better performance for detection of single photons in longer wavelength range. The difference in normalized photon count rate for such structures reaches one order of magnitude higher in comparison with structures based on NbN thin films at 2.5 μm. |
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1757-899X |
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no |
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Serial |
1799 |
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Xu, Y.; Zheng, X.; Williams, C.; Verevkin, A.; Sobolewski, R.; Chulkova, G.; Lipatov, A.; Okunev, O.; Smirnov, K.; Gol’tsman, G. N. |
| Title |
Ultrafast superconducting hot-electron single-photon detector |
Type |
Conference Article |
| Year |
2001 |
Publication |
CLEO |
Abbreviated Journal |
CLEO |
| Volume |
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Issue |
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Pages |
345 |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
Summary form only given. The current most-pressing need is to develop a practical, GHz-range counting single-photon detector, operational at either 1.3-/spl mu/m or 1.55-/spl mu/m radiation wavelength, for novel quantum communication and quantum cryptography systems. The presented solution of the problem is to use an ultrafast hot-electron photodetector, based on superconducting thin-film microstructures. This type of device is very promising, due to the macroscopic quantum nature of superconductors. Very fast response time and the small, (meV range) value of the superconducting energy gap characterize the superconductor, leading to the efficient avalanche process even for infrared photons. |
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Conference |
Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest (IEEE Cat. No.01CH37170) |
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Approved |
no |
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Serial |
1545 |
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