| Home | [21–30] << 31 32 33 34 35 36 37 38 39 40 >> [41–46] |
|
| Records | |||||
|---|---|---|---|---|---|
| Author | Shcherbatenko, M.; Elezov, M.; Manova, N.; Sedykh, K.; Korneev, A.; Korneeva, Y.; Dryazgov, M.; Simonov, N.; Feimov, A.; Goltsman, G.; Sych, D. | ||||
| Title | Single-pixel camera with a large-area microstrip superconducting single photon detector on a multimode fiber | Type | Journal Article | ||
| Year | 2021 | Publication | Appl. Phys. Lett. | Abbreviated Journal | Appl. Phys. Lett. |
| Volume | 118 | Issue | 18 | Pages | 181103 |
| Keywords | NbN SSPD, SNSPD | ||||
| Abstract | High sensitivity imaging at the level of single photons is an invaluable tool in many areas, ranging from microscopy to astronomy. However, development of single-photon sensitive detectors with high spatial resolution is very non-trivial. Here we employ the single-pixel imaging approach and demonstrate a proof-of-principle single-pixel single-photon imaging setup. We overcome the problem of low light gathering efficiency by developing a large-area microstrip superconducting single photon detector coupled to a multi-mode optical fiber interface. We show that the setup operates well in the visible and near infrared spectrum, and is able to capture images at the single-photon level. We thank Philipp Zolotov and Pavel Morozov for NbN film fabrication, ARC coating, and fiber coupling of the detector. We also thank Swabian Instruments GmbH and Dr. Helmut Fedder personally for the kindly provided experimental equipment (Time Tagger Ultra 8). The work in the part of SNSPD research and development was supported by the Russian Foundation for Basic Research Project No. 18-29-20100. The work in the part of the optical setup and imaging was supported by Russian Foundation for Basic Research Project No. 20-32-51004. |
||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0003-6951 | ISBN | Medium | ||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
Call Number  |
Serial | 1770 | |||
| Permanent link to this record | |||||
| Author | Neroev, V. V.; Iomdina, E. N.; Khandzhyan, A. T.; Khodzhabekyan, N. V.; Sengaeva, M. D.; Ivanova, A. V.; Seliverstov, S. V.; Teplyakova, K. O.; Goltsman, G. N. | ||||
| Title | Experimental study of the effect of corneal hydration and its biomechanical properties on the results of photorefractive keratectomy | Type | Journal Article | ||
| Year | 2021 | Publication | Vestn. Oftalmol. | Abbreviated Journal | Vestn. Oftalmol. |
| Volume | 137 | Issue | 3 | Pages | 68-75 |
| Keywords | THz scanning, cornea, photorefractive keratectomy, medicine | ||||
| Abstract | Water content in the cornea may affect the outcome of its excimer laser ablation, especially in presbyopic patients with myopic refraction. This hypothesis can be tested by scanning the cornea in the terahertz (THz) range to determine its hydration level. Purpose: To study the effect of hydration of the cornea determined by non-contact THz scanning and its biomechanical parameters on the results of photorefractive keratectomy (PRK) in an experiment. Material and methods: PRK was performed using the Nidek EC-5000 QUEST excimer laser on 8 rabbit eyes. Corneal hydration was evaluated by determining the reflection coefficient (RC) in the THz electromagnetic radiation range before PRK, after 3-5 days, and after 1, 2, 3, and 4 months. Clinical examination included autorefractometry, assessment of corneal thickness and other anatomical and optical parameters of the anterior eye segment (Galilei G6, Ziemer Ophthalmic Systems AG 6.0.2, Switzerland), measurement of corneal hysteresis (CH) and corneal resistance factor (CRF) using the Ocular Response Analyzer (ORA; Reichert, USA), as well as tear production (Schirmer test). Results: The initial water content in the cornea has a significant effect on the thickness of the removed layer, i.e. on the PRK effect, with correlation coefficient of Rs= -0.976 (p<0.01). The correlation between CH and the ablation depth is less pronounced (Rs=0.643), and CRF had no correlation with it (Rs= -0.089). Biomechanical indicators of the cornea depend on its hydration: changes in CH and CRF after excimer laser ablation qualitatively coincide with changes in RC, the correlation coefficient between RC and the initial value of CH is R= -0.619 (moderate negative correlation). Conclusion: THz scanning is an effective non-contact technology for monitoring corneal hydration level. The mismatch of the hypoeffect of keratorefractive excimer laser intervention planned for patients with presbyopia with the actual outcome can be caused by individual decrease in the initial water content in the cornea. |
||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Russian | Summary Language | Original Title | ||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number |
Serial | 1794 | |||
| Permanent link to this record | |||||
| Author | Smirnov, K.; Vachtomin, Y.; Divochiy, A.; Antipov, A.; Goltsman, G. | ||||
| Title | The limitation of noise equivalent power by background radiation for infrared superconducting single photon detectors coupled to standard single mode optical fibers | Type | Journal Article | ||
| Year | 2015 | Publication | Rus. J. Radio Electron. | Abbreviated Journal | Rus. J. Radio Electron. |
| Volume | Issue | 5 | Pages | ||
| Keywords | NbN SSPD | ||||
| Abstract | We investigated the minimum level of the dark count rates and noise equivalent power of superconducting single photon detectors coupled to standard single mode optical fibers. We found that background radiation limits the minimum level of the dark count rates. We also proposed the effective method for reducing background radiation out of the required spectral range of the detector. Measured noise equivalent power of detector reaches 8.9×10-19 W×Hz1/2 at a wavelength of 1.55 μm and quantum efficiency 35%. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | 14 pages | Approved | no | ||
| Call Number |
Serial | 1813 | |||
| Permanent link to this record | |||||
| Author | Semenov, A. V.; Devyatov, I. A.; Korneev, A. A.; Smirnov, K. V.; Goltsman, G. N.; Melnikov, A. P. | ||||
| Title | Derivation of expression for thermodynamic potential of “dirty” superconductor | Type | Journal Article | ||
| Year | 2012 | Publication | Rus. J. Radio Electron. | Abbreviated Journal | Rus. J. Radio Electron. |
| Volume | Issue | 4 | Pages | ||
| Keywords | dirty superconductor, Usadel theory, thermodynamic potential | ||||
| Abstract | We derive a formula for thermodynamic potential of dirty superconductor which express it via isotropic quasiclassical Green functions of Usadel theory. Our result allows unify description of dynamic processes and fluctuations in superconducting nano-electronic devices. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Russian | Summary Language | Original Title | ||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | 7 pages | Approved | no | ||
| Call Number |
Serial | 1824 | |||
| Permanent link to this record | |||||
| Author | 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. | ||||
| Title | Time-resolved measurements of light–current characteristic and mode competition in pulsed THz quantum cascade laser | Type | Journal Article | ||
| Year | 2021 | Publication | Optical Engineering | Abbreviated Journal | Optical Engineering |
| Volume | 60 | Issue | 8 | Pages | 1-8 |
| Keywords | 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. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Spie | Place of Publication | Editor | ||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number |
10.1117/1.Oe.60.8.082019 | Serial | 1260 | ||
| Permanent link to this record | |||||