Yuriy Divin | Forschungszentrum Juelich (original) (raw)
Papers by Yuriy Divin
Applied Sciences
Spectral analysis of terahertz (THz) and sub-THz emission from quantum cascade lasers has been re... more Spectral analysis of terahertz (THz) and sub-THz emission from quantum cascade lasers has been recently demonstrated using conventional YBa2Cu3O7−x bicrystal Josephson junctions made from c-axes thin films. Josephson frequencies of alternative bicrystal junctions made from YBa2Cu3O7−x films with mutually tilted c-axes extend further into the THz range. However, these THz oscillations can weaken due to new absorption channels in the junction environment. Here, using Josephson admittance spectroscopy, THz losses in YBa2Cu3O7−x bicrystal junctions with mutually tilted c-axes are studied. Absorption maximizes at a reproducible set of THz frequencies close to those of collective modes in bulk YBa2Cu3O7−x recovered by Fourier spectroscopy. Annealing junctions in atomic oxygen reduces the losses at frequencies of 2.7 and 3.6 THz, while the losses increase at frequencies of 2.3 and 4.6 THz. Thus, as a THz spectrum analyzer, YBa2Cu3O7−x bicrystal junctions require post-fabrication correction...
Applied Physics Letters
We have detected subterahertz spectral lines in the emission of free-running GaAs/AlGaAs quantum ... more We have detected subterahertz spectral lines in the emission of free-running GaAs/AlGaAs quantum cascade lasers (QCLs) operating around 3 THz. We have found that the power W( fd) of an individual sub-THz line at the frequency fd is directly proportional to a power product W( fi) × W( fk) of the corresponding pair of THz lines having the frequency difference fi − fk = fd. The established one-to-one correspondence of each sub-THz line to pair combinations of THz lines proves the nonlinear mechanism of difference-frequency generation (DFG) in the QCL active region. The conversion efficiencies W( fi − fk)/[ W( fi) × W( fk)] estimated from the experimental data are about 4 × 10−3 and 5 × 10−5 W−1 for the sub-THz lines found at 132 and 310 GHz, correspondingly. Considering nonlinear polarization of QCL active regions as the reason for DFG, we have evaluated the following values of the second-order nonlinear susceptibility χ(2)(132 GHz) ≅ 7 × 105 pm/V and χ(2)(310 GHz) ≅ 4 × 104 pm/V from...
Journal of Communications Technology and Electronics, 2019
Analytical and numerical calculations of limiting characteristics of electromagnetic radiation de... more Analytical and numerical calculations of limiting characteristics of electromagnetic radiation detectors based on Josephson junctions are carried out. Josephson junctions are described by a simple resistively shunted model and their Josephson energy is considered to be comparable to the energy of thermal fluctuations. The operation modes of such junctions as a classical detector using ac rectification on a static nonlinear current-voltage characteristic are established. The results of numerical and analytical calculations are compared, and it is shown that the classical detection mode can be analyzed and optimized using the derived analytical expressions for the main limiting characteristics. The study demonstrates the possibility of achieving a limiting sensitivity up to 2 × 10-15 W/Hz 1/2 , a dynamic power range of 10 5-10 6 , and a spectral range up to 1.4 THz, in a temperature range 50-77 K using new Josephson thin-film junctions consisting of high-temperature YBa 2 Cu 3 O 7-x superconductors with mutually tilted c axes.
IEEE Transactions on Magnetics, 1991
We have investigated the effect of millimeter-wave electromagnetic radiation on the I-V curves of... more We have investigated the effect of millimeter-wave electromagnetic radiation on the I-V curves of superconducting bridges made from polycrystalline YBa films with the grain size a-1 pm and the critigal current density j(4.2K)-lO4A/cm? When the bridge dimensions wxl were dgcreased from 20Ox200pm' to 5x5pm2, the effect of radiation at T<<T changed from heating (for bridges with w, 12100pm) tb vortex synchronization [20pm<w,1<100pm) and after that (w, 1C20pm) to synchronization of Josephson oscillations. Josephson behavior of the bridges with w,l<ZOpm was shown to be related to large-scale percolation processes in the system of intergrain Josephson junctions with the characteristic percolation length L-20pm. In was demonstrated that bridges with w,l<L could have values of noise equivalent power NEP<lO-''W/Hz " ' a t T=40K.
IEEE Transactions on Magnetics, 1989
IEEE Transactions on Magnetics, 1991
The size effects in electrical characteristics of polycrystalline YBa2Cu3O7-x thin-film bridges w... more The size effects in electrical characteristics of polycrystalline YBa2Cu3O7-x thin-film bridges were studied in the temperature range 4-300 K. It is shown that at T>Tc the decrease of bridge widths w from 200 to 10 μm leads to an increase of resistance R&square; of several times and to a change in R&square; (T) behavior from a metallic type to an
Sov. J. Low Temp. Phys.(Engl. Transl.);(United States), 1978
... Model of real superconducting point contacts. Description/Abstract. A model of real supercond... more ... Model of real superconducting point contacts. Description/Abstract. A model of real superconducting point contacts is proposed based on the experimental studies of superconducting point contact properties in the resistance range 10/sup 5/--10/sup -1/ ..cap omega.. ...
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)
The longitudinal charge distribution of an electron/positron bunch can be determined from the coh... more The longitudinal charge distribution of an electron/positron bunch can be determined from the coherent transition radiation emitted as the bunch crosses a thin metal foil. A Josephson junction made from a thin film of YBa 2 Cu 3 O 7,x on a bicrystal substrate is used as a detector for transition radiation in the millimeter and submillimeter range. The spectral intensity of the radiation and the longitudinal form factor of the bunch are derived by applying a Hilbert transformation to the radiation-induced modification of the current-voltage characteristic of the Josephson junction. The physical principles of a Josephson junction as a detector for submillimeter radiation are outlined and a first bunch length measurement is presented.
2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2018
Resonance modes in a planar square split-ring resonator (SRR) have been studied by Josephson spec... more Resonance modes in a planar square split-ring resonator (SRR) have been studied by Josephson spectroscopy at frequencies from 150 GHz to 800 GHz and excitation of fundamental modes in internal and external resonators have been observed. In addition, a square open-loop resonator (OLR) of the same dimension as the external resonator of the SRR has been analyzed, and red shift of the low-frequency resonance mode in SRR has been demonstrated.
2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz), 2016
Here we report the results of terahertz photonic elements frequency analysis by the ac Josephson ... more Here we report the results of terahertz photonic elements frequency analysis by the ac Josephson effect. We considered planar resonators. There were observed excitation of fundamental and dipole resonance modes in photonic elements by Josephson oscillations of YBa2Cu3O7-x bicrystal junction. Spectral characteristics of electrodynamic structures were restored with the usage of equivalent circuit. Regimes of interaction of resonator structures with Josephson junction were analyzed.
Research fields Superconducting electronics, especially applications of the ac Josephson effect f... more Research fields Superconducting electronics, especially applications of the ac Josephson effect for THz detection, spectroscopy and imaging of electromagnetic radiation. Current research studies are within physics, technology and terahertz applications of high-Tc Josephson junctions. Special emphasis on demanding THz applications with unique combination of broad bandwidth, high speed and large dynamic range, like in public security or hot plasma diagnostics. More than 170 scientific publications and 8 patents in the field. Hirsh-factor h = 17.
Verhandlungen der Deutschen Physikalischen Gesellschaft, 2001
2017 42nd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2017
Excitation of various resonance modes in a square open-loop resonator was studied by Josephson sp... more Excitation of various resonance modes in a square open-loop resonator was studied by Josephson spectroscopy. A copper resonator with a side of a square of 233 μm was fabricated. Changing the position of the resonator with respect to a bicrystal YBa2Cu3O7−x Josephson junction, a number of resonances was observed in measured spectra with the center frequencies from 78 GHz to 218 GHz. Measured data were compared with the results of a numeric simulation using an equivalent circuit of the resonator interacting with the junction. Resonance frequencies were obtained by fitting of calculated characteristics to the measured ones. According to the geometry of electric and magnetic field distributions for each position of the resonator, resonances observed were ascribed to excitation of fundamental magnetic and plasmonic modes.
Broadband electromagnetic measurement at frequencies above 100 GHz is still challenging problem b... more Broadband electromagnetic measurement at frequencies above 100 GHz is still challenging problem because of limited frequency ranges of oscillators, complicated matching networks and ambiguous deembedding procedures. It is known that Josephson junction (JJ) is very sensitive to electromagnetic environment. Josephson terahertz spectroscopy is based on ac Josephson effect in high-temperature superconducting junctions. Here we extend this method to perform spectral characterization of planar open ring resonators on separate substrates. We have studied resonator characteristics at frequencies from 50 GHz to 700 GHz, using YBa2Cu3O7ix high-Tc bicrystal grain boundary junctions on NdGaO3 and MgO substrates. Differential resistance vs. voltage curves modifed by the interaction of JJ with resonator have been analyzed. An excitation of fundamental resonance mode in the planar resonator by Josephson oscillations was demonstrated. The technique developed might be used for frequency characteriza...
2017 Progress In Electromagnetics Research Symposium - Spring (PIERS), 2017
An excitation of various resonance modes in a square open-loop resonator were studied by Josephso... more An excitation of various resonance modes in a square open-loop resonator were studied by Josephson spectroscopy. Copper resonator with square side sizes 234 μm and 173 μm correspondingly and 5 μm cut width was explored. Using different arrangements of the resonator against planar bicrystal Josephson junction from YBa2Cu3O7−x a number of resonances was observed in a frequency range from 60 GHz to 350 GHz. These resonances correspond to excitation of fundamental magnetic mode at frequency of 71 GHz, even plazmonic mode at frequency of 151 GHz and unhybridized plazmonic mode at frequency of 230 GHz. Experimental results were corroborated by the results of numerical simulation.
Superconductor Science and Technology, 2017
Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the tech... more Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the technique in the terahertz (THz) frequency range are discussed. THz HTSA requires Josephson junctions with high values of characteristic voltages I c R n and dynamics described by a simple resistively shunted junction (RSJ) model. To meet these requirements, [001]- and [100]-tilt YBa2Cu3O7−x bicrystal junctions with deviations from the RSJ model less than 1% have been developed. Demonstrators of Hilbert-transform spectrum analyzers with various cryogenic environments, including integration into Stirling coolers, are described. Spectrum analyzers have been characterized in the spectral range from 50 GHz to 3 THz. Inside a power dynamic range of five orders, an instrumental function of the analyzers has been found to have a Lorentz form around a single frequency of 1.48 THz with a spectral resolution as low as 0.9 GHz. Spectra of THz radiation from optically pumped gas lasers and semiconductor frequency multipliers have been studied with these spectrum analyzers and the regimes of these radiation sources were optimized for a single-frequency operation. Future applications of HTSA will be related with quick and precise spectral characterization of new radiation sources and identification of substances in the THz frequency range.
Physics Procedia, 2012
Specific values of characteristic voltages I c R n and normal-state resistances R n of high-T c J... more Specific values of characteristic voltages I c R n and normal-state resistances R n of high-T c Josephson junctions (JJ) are often required for their THz applications in detection and spectroscopy. Recently, evolution of these electrical parameters of [001]-tilt YBa 2 Cu 3 O 7-x bicrystal JJ after low-temperature ozone annealing has been studied. Here, we present the effect of ozone and vacuum annealing on the IV-curves of [100]-tilt YBa 2 Cu 3 O 7-x bicrystal JJ. Annealing temperature T a was varied from 100 C to 225 C. It was demonstrated, that annealing in ozone-oxygen mixture and in vacuum has an opposite effect on JJ parameters, and the changes were reversible at T a up to 145 C. Ozone annealing at T a =100 C resulted in up to 1.5 times decrease of R n. After annealing in vacuum at higher T a , a transition temperature T c of JJ electrodes was reduced from 90 K to 52K, and significant, multifold changes of I c R n and R n were observed. Further annealing in ozone at T a up to 225 C restored T c and R n almost to their initial values, but I c R nvalues couldn't be increased above 20% of the initial value. The obtained results can be used for trimming of junction parameters after main fabrication procedure.
Infrared and Millimeter Waves, Conference Digest of the 2004 Joint 29th International Conference on 2004 and 12th International Conference on Terahertz Electronics, 2004.
Frequency-selective high-T, Josephson detectors have been fabricated and characterized. A spectra... more Frequency-selective high-T, Josephson detectors have been fabricated and characterized. A spectral range from 15 GHz lo 4.3 THz has been demonstrated for these detectors. A power dynamic range of 50 dB and a noise equivalent power of IO^" WMztn have been realized. A spectral resolution &' Jof IO" has been achieved in the terahertz range. As an alternative to Fourier-transform spectroscopy. fast Hilbert-transform spectroscopy, based on these detectors, have been applied for various cw and pulsed terahem sources.
2005 18th International Conference on Applied Electromagnetics and Communications, 2005
ABSTRACT Frequency-selective and broadband high-T c Josephson detectors have been fabricated and ... more ABSTRACT Frequency-selective and broadband high-T c Josephson detectors have been fabricated and characterized. A spectral range from 15 GHz to 5.3 THz has been demonstrated for these detectors. A power dynamic range of 50 dB and a noise equivalent power of 10-14W/Hz1/2have been realized. A spectral resolution δf/f of 10-3has been achieved in the terahertz range. As an alternative to Fourier-transform spectroscopy, fast Hilbert-transform spectroscopy, based on these detectors, has been applied for various cw and pulsed terahertz sources.
ABSTRACT We have studied low-frequency noise in [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Joseph... more ABSTRACT We have studied low-frequency noise in [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Josephson junctions with high characteristic voltages in comparison with the noise of conventional [001]-tilt junctions. [001]-tilt junctions on MgO and NdGaO 3 substrates and [100]-tilt junctions on NdGaO 3 substrate were characterized at the voltage range of 0-15mV, at the frequency range of 100Hz-25.6kHz and in the temperature interval of 55-75K. [001]-tilt junctions on MgO and NdGaO 3 substrates and [100]-tilt junctions on NdGaO 3 substrates had the characteristic voltages of 0.2mV, 0.25mV and 0.8mV at T=75K, correspondingly. The |GI c /I c ||GR n /R n | ratio for our junctions had an average value of 1.5. The low value of this ratio can be explained by direct tunnelling carrying the part of the quasiparticle current. The scaling dependence of S R on the R n value was found independent on the type of the junction. [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Josephson junctions on NdGaO 3 substrates are considered to be more attractive for radiation detection and spectroscopy at terahertz frequencies, because the signal-noise ratio will be better for this type of junctions due to the high values of the characteristic voltages.
Applied Sciences
Spectral analysis of terahertz (THz) and sub-THz emission from quantum cascade lasers has been re... more Spectral analysis of terahertz (THz) and sub-THz emission from quantum cascade lasers has been recently demonstrated using conventional YBa2Cu3O7−x bicrystal Josephson junctions made from c-axes thin films. Josephson frequencies of alternative bicrystal junctions made from YBa2Cu3O7−x films with mutually tilted c-axes extend further into the THz range. However, these THz oscillations can weaken due to new absorption channels in the junction environment. Here, using Josephson admittance spectroscopy, THz losses in YBa2Cu3O7−x bicrystal junctions with mutually tilted c-axes are studied. Absorption maximizes at a reproducible set of THz frequencies close to those of collective modes in bulk YBa2Cu3O7−x recovered by Fourier spectroscopy. Annealing junctions in atomic oxygen reduces the losses at frequencies of 2.7 and 3.6 THz, while the losses increase at frequencies of 2.3 and 4.6 THz. Thus, as a THz spectrum analyzer, YBa2Cu3O7−x bicrystal junctions require post-fabrication correction...
Applied Physics Letters
We have detected subterahertz spectral lines in the emission of free-running GaAs/AlGaAs quantum ... more We have detected subterahertz spectral lines in the emission of free-running GaAs/AlGaAs quantum cascade lasers (QCLs) operating around 3 THz. We have found that the power W( fd) of an individual sub-THz line at the frequency fd is directly proportional to a power product W( fi) × W( fk) of the corresponding pair of THz lines having the frequency difference fi − fk = fd. The established one-to-one correspondence of each sub-THz line to pair combinations of THz lines proves the nonlinear mechanism of difference-frequency generation (DFG) in the QCL active region. The conversion efficiencies W( fi − fk)/[ W( fi) × W( fk)] estimated from the experimental data are about 4 × 10−3 and 5 × 10−5 W−1 for the sub-THz lines found at 132 and 310 GHz, correspondingly. Considering nonlinear polarization of QCL active regions as the reason for DFG, we have evaluated the following values of the second-order nonlinear susceptibility χ(2)(132 GHz) ≅ 7 × 105 pm/V and χ(2)(310 GHz) ≅ 4 × 104 pm/V from...
Journal of Communications Technology and Electronics, 2019
Analytical and numerical calculations of limiting characteristics of electromagnetic radiation de... more Analytical and numerical calculations of limiting characteristics of electromagnetic radiation detectors based on Josephson junctions are carried out. Josephson junctions are described by a simple resistively shunted model and their Josephson energy is considered to be comparable to the energy of thermal fluctuations. The operation modes of such junctions as a classical detector using ac rectification on a static nonlinear current-voltage characteristic are established. The results of numerical and analytical calculations are compared, and it is shown that the classical detection mode can be analyzed and optimized using the derived analytical expressions for the main limiting characteristics. The study demonstrates the possibility of achieving a limiting sensitivity up to 2 × 10-15 W/Hz 1/2 , a dynamic power range of 10 5-10 6 , and a spectral range up to 1.4 THz, in a temperature range 50-77 K using new Josephson thin-film junctions consisting of high-temperature YBa 2 Cu 3 O 7-x superconductors with mutually tilted c axes.
IEEE Transactions on Magnetics, 1991
We have investigated the effect of millimeter-wave electromagnetic radiation on the I-V curves of... more We have investigated the effect of millimeter-wave electromagnetic radiation on the I-V curves of superconducting bridges made from polycrystalline YBa films with the grain size a-1 pm and the critigal current density j(4.2K)-lO4A/cm? When the bridge dimensions wxl were dgcreased from 20Ox200pm' to 5x5pm2, the effect of radiation at T<<T changed from heating (for bridges with w, 12100pm) tb vortex synchronization [20pm<w,1<100pm) and after that (w, 1C20pm) to synchronization of Josephson oscillations. Josephson behavior of the bridges with w,l<ZOpm was shown to be related to large-scale percolation processes in the system of intergrain Josephson junctions with the characteristic percolation length L-20pm. In was demonstrated that bridges with w,l<L could have values of noise equivalent power NEP<lO-''W/Hz " ' a t T=40K.
IEEE Transactions on Magnetics, 1989
IEEE Transactions on Magnetics, 1991
The size effects in electrical characteristics of polycrystalline YBa2Cu3O7-x thin-film bridges w... more The size effects in electrical characteristics of polycrystalline YBa2Cu3O7-x thin-film bridges were studied in the temperature range 4-300 K. It is shown that at T>Tc the decrease of bridge widths w from 200 to 10 μm leads to an increase of resistance R&square; of several times and to a change in R&square; (T) behavior from a metallic type to an
Sov. J. Low Temp. Phys.(Engl. Transl.);(United States), 1978
... Model of real superconducting point contacts. Description/Abstract. A model of real supercond... more ... Model of real superconducting point contacts. Description/Abstract. A model of real superconducting point contacts is proposed based on the experimental studies of superconducting point contact properties in the resistance range 10/sup 5/--10/sup -1/ ..cap omega.. ...
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)
The longitudinal charge distribution of an electron/positron bunch can be determined from the coh... more The longitudinal charge distribution of an electron/positron bunch can be determined from the coherent transition radiation emitted as the bunch crosses a thin metal foil. A Josephson junction made from a thin film of YBa 2 Cu 3 O 7,x on a bicrystal substrate is used as a detector for transition radiation in the millimeter and submillimeter range. The spectral intensity of the radiation and the longitudinal form factor of the bunch are derived by applying a Hilbert transformation to the radiation-induced modification of the current-voltage characteristic of the Josephson junction. The physical principles of a Josephson junction as a detector for submillimeter radiation are outlined and a first bunch length measurement is presented.
2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2018
Resonance modes in a planar square split-ring resonator (SRR) have been studied by Josephson spec... more Resonance modes in a planar square split-ring resonator (SRR) have been studied by Josephson spectroscopy at frequencies from 150 GHz to 800 GHz and excitation of fundamental modes in internal and external resonators have been observed. In addition, a square open-loop resonator (OLR) of the same dimension as the external resonator of the SRR has been analyzed, and red shift of the low-frequency resonance mode in SRR has been demonstrated.
2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz), 2016
Here we report the results of terahertz photonic elements frequency analysis by the ac Josephson ... more Here we report the results of terahertz photonic elements frequency analysis by the ac Josephson effect. We considered planar resonators. There were observed excitation of fundamental and dipole resonance modes in photonic elements by Josephson oscillations of YBa2Cu3O7-x bicrystal junction. Spectral characteristics of electrodynamic structures were restored with the usage of equivalent circuit. Regimes of interaction of resonator structures with Josephson junction were analyzed.
Research fields Superconducting electronics, especially applications of the ac Josephson effect f... more Research fields Superconducting electronics, especially applications of the ac Josephson effect for THz detection, spectroscopy and imaging of electromagnetic radiation. Current research studies are within physics, technology and terahertz applications of high-Tc Josephson junctions. Special emphasis on demanding THz applications with unique combination of broad bandwidth, high speed and large dynamic range, like in public security or hot plasma diagnostics. More than 170 scientific publications and 8 patents in the field. Hirsh-factor h = 17.
Verhandlungen der Deutschen Physikalischen Gesellschaft, 2001
2017 42nd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2017
Excitation of various resonance modes in a square open-loop resonator was studied by Josephson sp... more Excitation of various resonance modes in a square open-loop resonator was studied by Josephson spectroscopy. A copper resonator with a side of a square of 233 μm was fabricated. Changing the position of the resonator with respect to a bicrystal YBa2Cu3O7−x Josephson junction, a number of resonances was observed in measured spectra with the center frequencies from 78 GHz to 218 GHz. Measured data were compared with the results of a numeric simulation using an equivalent circuit of the resonator interacting with the junction. Resonance frequencies were obtained by fitting of calculated characteristics to the measured ones. According to the geometry of electric and magnetic field distributions for each position of the resonator, resonances observed were ascribed to excitation of fundamental magnetic and plasmonic modes.
Broadband electromagnetic measurement at frequencies above 100 GHz is still challenging problem b... more Broadband electromagnetic measurement at frequencies above 100 GHz is still challenging problem because of limited frequency ranges of oscillators, complicated matching networks and ambiguous deembedding procedures. It is known that Josephson junction (JJ) is very sensitive to electromagnetic environment. Josephson terahertz spectroscopy is based on ac Josephson effect in high-temperature superconducting junctions. Here we extend this method to perform spectral characterization of planar open ring resonators on separate substrates. We have studied resonator characteristics at frequencies from 50 GHz to 700 GHz, using YBa2Cu3O7ix high-Tc bicrystal grain boundary junctions on NdGaO3 and MgO substrates. Differential resistance vs. voltage curves modifed by the interaction of JJ with resonator have been analyzed. An excitation of fundamental resonance mode in the planar resonator by Josephson oscillations was demonstrated. The technique developed might be used for frequency characteriza...
2017 Progress In Electromagnetics Research Symposium - Spring (PIERS), 2017
An excitation of various resonance modes in a square open-loop resonator were studied by Josephso... more An excitation of various resonance modes in a square open-loop resonator were studied by Josephson spectroscopy. Copper resonator with square side sizes 234 μm and 173 μm correspondingly and 5 μm cut width was explored. Using different arrangements of the resonator against planar bicrystal Josephson junction from YBa2Cu3O7−x a number of resonances was observed in a frequency range from 60 GHz to 350 GHz. These resonances correspond to excitation of fundamental magnetic mode at frequency of 71 GHz, even plazmonic mode at frequency of 151 GHz and unhybridized plazmonic mode at frequency of 230 GHz. Experimental results were corroborated by the results of numerical simulation.
Superconductor Science and Technology, 2017
Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the tech... more Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the technique in the terahertz (THz) frequency range are discussed. THz HTSA requires Josephson junctions with high values of characteristic voltages I c R n and dynamics described by a simple resistively shunted junction (RSJ) model. To meet these requirements, [001]- and [100]-tilt YBa2Cu3O7−x bicrystal junctions with deviations from the RSJ model less than 1% have been developed. Demonstrators of Hilbert-transform spectrum analyzers with various cryogenic environments, including integration into Stirling coolers, are described. Spectrum analyzers have been characterized in the spectral range from 50 GHz to 3 THz. Inside a power dynamic range of five orders, an instrumental function of the analyzers has been found to have a Lorentz form around a single frequency of 1.48 THz with a spectral resolution as low as 0.9 GHz. Spectra of THz radiation from optically pumped gas lasers and semiconductor frequency multipliers have been studied with these spectrum analyzers and the regimes of these radiation sources were optimized for a single-frequency operation. Future applications of HTSA will be related with quick and precise spectral characterization of new radiation sources and identification of substances in the THz frequency range.
Physics Procedia, 2012
Specific values of characteristic voltages I c R n and normal-state resistances R n of high-T c J... more Specific values of characteristic voltages I c R n and normal-state resistances R n of high-T c Josephson junctions (JJ) are often required for their THz applications in detection and spectroscopy. Recently, evolution of these electrical parameters of [001]-tilt YBa 2 Cu 3 O 7-x bicrystal JJ after low-temperature ozone annealing has been studied. Here, we present the effect of ozone and vacuum annealing on the IV-curves of [100]-tilt YBa 2 Cu 3 O 7-x bicrystal JJ. Annealing temperature T a was varied from 100 C to 225 C. It was demonstrated, that annealing in ozone-oxygen mixture and in vacuum has an opposite effect on JJ parameters, and the changes were reversible at T a up to 145 C. Ozone annealing at T a =100 C resulted in up to 1.5 times decrease of R n. After annealing in vacuum at higher T a , a transition temperature T c of JJ electrodes was reduced from 90 K to 52K, and significant, multifold changes of I c R n and R n were observed. Further annealing in ozone at T a up to 225 C restored T c and R n almost to their initial values, but I c R nvalues couldn't be increased above 20% of the initial value. The obtained results can be used for trimming of junction parameters after main fabrication procedure.
Infrared and Millimeter Waves, Conference Digest of the 2004 Joint 29th International Conference on 2004 and 12th International Conference on Terahertz Electronics, 2004.
Frequency-selective high-T, Josephson detectors have been fabricated and characterized. A spectra... more Frequency-selective high-T, Josephson detectors have been fabricated and characterized. A spectral range from 15 GHz lo 4.3 THz has been demonstrated for these detectors. A power dynamic range of 50 dB and a noise equivalent power of IO^" WMztn have been realized. A spectral resolution &' Jof IO" has been achieved in the terahertz range. As an alternative to Fourier-transform spectroscopy. fast Hilbert-transform spectroscopy, based on these detectors, have been applied for various cw and pulsed terahem sources.
2005 18th International Conference on Applied Electromagnetics and Communications, 2005
ABSTRACT Frequency-selective and broadband high-T c Josephson detectors have been fabricated and ... more ABSTRACT Frequency-selective and broadband high-T c Josephson detectors have been fabricated and characterized. A spectral range from 15 GHz to 5.3 THz has been demonstrated for these detectors. A power dynamic range of 50 dB and a noise equivalent power of 10-14W/Hz1/2have been realized. A spectral resolution δf/f of 10-3has been achieved in the terahertz range. As an alternative to Fourier-transform spectroscopy, fast Hilbert-transform spectroscopy, based on these detectors, has been applied for various cw and pulsed terahertz sources.
ABSTRACT We have studied low-frequency noise in [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Joseph... more ABSTRACT We have studied low-frequency noise in [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Josephson junctions with high characteristic voltages in comparison with the noise of conventional [001]-tilt junctions. [001]-tilt junctions on MgO and NdGaO 3 substrates and [100]-tilt junctions on NdGaO 3 substrate were characterized at the voltage range of 0-15mV, at the frequency range of 100Hz-25.6kHz and in the temperature interval of 55-75K. [001]-tilt junctions on MgO and NdGaO 3 substrates and [100]-tilt junctions on NdGaO 3 substrates had the characteristic voltages of 0.2mV, 0.25mV and 0.8mV at T=75K, correspondingly. The |GI c /I c ||GR n /R n | ratio for our junctions had an average value of 1.5. The low value of this ratio can be explained by direct tunnelling carrying the part of the quasiparticle current. The scaling dependence of S R on the R n value was found independent on the type of the junction. [100]-tilt YBa 2 Cu 3 O 7-X grain-boundary Josephson junctions on NdGaO 3 substrates are considered to be more attractive for radiation detection and spectroscopy at terahertz frequencies, because the signal-noise ratio will be better for this type of junctions due to the high values of the characteristic voltages.