| Records |
| Author |
Nikogosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. |
Title  |
Effect of absorption on the efficiency of terahertz radiation generation in the metal waveguide partially filled with nonlinear crystal LiNbO3, DAST or ZnTe |
Type |
Journal Article |
| Year |
2019 |
Publication |
J. Contemp. Phys. |
Abbreviated Journal |
J. Contemp. Phys. |
| Volume |
54 |
Issue |
1 |
Pages |
97-104 |
| Keywords |
nonlinear crystal, THz, waveguide |
| Abstract |
The influence of terahertz (THz) radiation absorption on the efficiency of generation of coherent THz radiation in the system ‘nonlinear-optical crystal partially filling the cross section of a rectangular metal waveguide’ has been investigated. The efficiency of the nonlinear frequency conversion of optical laser radiation to the THz range depends on the loss in the system and the fulfillment of the phase-matching (FM) condition in a nonlinear crystal. The method of partially filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. The phase matching is achieved by numerical determination of the thickness of the nonlinear crystal, that is the degree of partial filling of the waveguide. The attenuation of THz radiation caused by losses both in the metal walls of the waveguide and in the crystal was studied, taking into account the dimension of the cross section of the waveguide, the degree of partial filling, and the dielectric constant of the crystal. It is shown that the partial filling of the waveguide with a nonlinear crystal results in an increase in the efficiency of generation of THz radiation by an order of magnitude, owing to the decrease in absorption. |
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1068-3372 |
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1289 |
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Nikoghosyan, A. S.; Martirosyan, R. M.; Hakhoumian, A. A.; Makaryan, A. H.; Tadevosyan, V. R.; Goltsman, G. N.; Antipov, S. V. |
| Title |
Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide |
Type |
Journal Article |
| Year |
2018 |
Publication |
Armenian J. Phys. |
Abbreviated Journal |
Armenian J. Phys. |
| Volume |
11 |
Issue |
4 |
Pages |
257-262 |
| Keywords |
THz, waveguide, nonlinear crystal |
| Abstract |
The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant. |
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1829-1171 |
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1291 |
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Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Riger, E. R. |
| Title |
Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium |
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Journal Article |
| Year |
1986 |
Publication |
Sov. Phys. JETP |
Abbreviated Journal |
Sov. Phys. JETP |
| Volume |
64 |
Issue |
4 |
Pages |
889-897 |
| Keywords |
Ge, trapping of free carriers |
| Abstract |
Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3). |
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1707 |
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Elant'ev, A. I.; Karasik, B. S. |
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Effect of high-frequency current on Nb superconductive film in resistive state |
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Journal Article |
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1989 |
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Sov. J. Low Temp. Phys. |
Abbreviated Journal |
Sov. J. Low Temp. Phys. |
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15 |
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7 |
Pages |
379-383 |
| Keywords |
Nb HEB |
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882 |
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Lusche, R.; Semenov, A.; Korneeva, Y.; Trifonov, A.; Korneev, A.; Gol'tsman, G.; Hübers, H.-W. |
| Title |
Effect of magnetic field on the photon detection in thin superconducting meander structures |
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Journal Article |
| Year |
2014 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
89 |
Issue |
10 |
Pages |
104513 (1 to 7) |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
We have studied the influence of an externally applied magnetic field on the photon and dark count rates of meander-type niobium nitride superconducting nanowire single-photon detectors. Measurements have been performed at a temperature of 4.2 K, and magnetic fields up to 250 mT have been applied perpendicularly to the meander plane. While photon count rates are field independent at weak applied fields, they show a strong dependence at fields starting from approximately ±25 mT. This behavior, as well as the magnetic field dependence of the dark count rates, is in good agreement with the recent theoretical model of vortex-assisted photon detection and spontaneous vortex crossing in narrow superconducting lines. However, the local reduction of the superconducting free energy due to photon absorption, which is the fitting parameter in the model, increases much slower with the photon energy than the model predicts. Furthermore, changes in the free-energy during photon counts and dark counts depend differently on the current that flows through the meander. This indicates that photon counts and dark counts occur in different parts of the meander. |
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1098-0121 |
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1367 |
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