Josephson spectroscopy at submillimetre waves (original) (raw)
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IEEE Transactions on Appiled Superconductivity, 1997
We have demonstrated the first applications of Josephson-effect-based Hilbert-transform spectral analysis using high-Tc Josephson junctions. Y B a~C u 3 0 7 -~ grainboundary Josephson junctions have been fabricated on (110) NdGa03 bicrystal substrates for these measurements. At first, spectra of Josephson radiation have been measured by Hilberttransform technique in the range 60 -800 GI%. A Lorentzian shape oft Josephson radiation and possibility to obtain a spectral resolution as low as 0.1 cm-1 in the submillimeterwave range has been demonstrated at liquid nitrogen temperature. At second, spectra of high-harmonic content of the radiation coming from commercial millimeter-wave oscillators have been measured by Hilbert-transform technique in the spectral range from 60 to 450 GHz. The comparison o f Hilbert-transform spectral analysis with conventional techniques is given.
Millimeter-wave Hilbert-transform spectroscopy with high-Tc Josephson junctions
Applied Physics Letters, 1996
The application of Hilbert-transform spectroscopy for the measurement of high-harmonic content of the radiation from a frequency multiplier has been demonstrated in the spectral range from 60 to 450 GHz. YBa 2 Cu 3 O 7-x grain-boundary Josephson junctions made on (110) NdGaO 3 bicrystal substrates have been used in these experiments. The internal Josephson radiation of the junctions reveals a Lorentzian shape due to thermal noise broadening. The possibility to obtain a spectral resolution as low as 280 MHz (0.01 cm -1 ) has been shown with a Josephson junction operating at liquid nitrogen temperature.
IEEE Transactions on Appiled Superconductivity, 1999
First laboratory prototypes of Hilbert-transform spectrometers have been developed. To meet the requirements of Hilbert-transform spectroscopy, high-T c Josephson junctions with RSJ-like behavior have been fabricated on twin-free NdGaO 3 bicrystal substrates. The operation of the spectrometers has been demonstrated from 60 GHz up to 2.25 THz. The first out-of-lab application of Hilbert-transform spectrometers has been successfully demonstrated at the TESLA Test Facility linear accelerator at DESY (Hamburg). The spectra of coherent transition electromagnetic radiation from electron bunches have been measured and a bunch length of s t = 1.2 ps has been derived from these spectra. The market perspectives of Hilbert spectrometers have been estimated.
Physica C-superconductivity and Its Applications, 2002
The submillimeter wave signal detection has been experimentally studied for a high-Tc superconducting device, consisting of a bicrystal YBa2Cu3Ox Josephson junction, incorporated with a log-periodic antenna. Measurements were carried out in wide range of temperatures T=20–80 K. At relatively high temperatures T>60 K, the thermally activated phase slippage began to predominate. At the same time, a set of clearly resolved detector response functions have been registered up to the temperatures close to the critical one. At the highest temperature T≃80 K, where detector response has been registered, the ratio of the frequency of applied signal fs≃500 GHz to the critical frequency of Josephson junction fc has been estimated as large as fs/fc≃40.
Hilbert spectroscopy from gigahertz to terahertz frequencies by high-Tc Josephson junctions
Physica C: Superconductivity, 2002
Hilbert spectroscopy is based on a frequency-selective detection of electromagnetic radiation by a Josephson junction described by the resistively shunted junction (RSJ) model. The YBa 2 Cu 3 O 7-x grain-boundary junctions fabricated on NdGaO 3 bicrystals were found to be close to the RSJ model. General-purpose Hilbert spectrometers integrated into a LHe/LN-filled dewars and a Stirling cryocooler were developed and characterized. The spectral bandwidth of Hilbert spectroscopy was shown to be of several frequency decades for any junction temperature between 48 and 85 K. A total bandwidth from 6 GHz to 2.5 THz has been covered using one junction at different temperatures. The spectral resolving power f/δf of Hilbert spectroscopy was found to be of three orders in the terahertz range. The dynamic range of intensities of electromagnetic radiation in Hilbert spectroscopy was shown to be of five orders. An example of application of Hilbert spectroscopy for the optimization of a single-line operation of optically pumped far-infrared gas laser is presented.
High-$T_{c}$ Josephson Square-Law Detectors and Hilbert Spectroscopy for Security Applications
IEEE Sensors Journal, 2000
Among various discussed ways of explosive detection, the techniques using electromagnetic radiation are considered as having great potential and research activities are recommended in this field. To identify new threats, like liquid explosives, with low rate of false alarms, fast spectral measurements are required in a broad frequency range from microwave to terahertz. We attract attention to a great potential of high-T c Josephson technology in security applications and present our results in developing high-T c Josephson junctions for Hilbert spectroscopy and detector arrays.
Terahertz Hilbert-transform spectral analysis with high-Tc Josephson junctions: first applications
1998
Our recent results on Hilbert-transform spectral analysis based on ac Josephson effect are reported. High-quality epitaxial YBa2Cu3O7-x thin-film Josephson junctions have been fabricated on untwinned (110) NdGaO3 bicrystal substrates to satisfy the operational requirements of Hilbert-transform technique. The design and characteristics of the developed laboratory Hilbert-transform spectrometers are presented. Spectra of Josephson radiation in high-Tc junctions have been measured in the frequency range from 60 to 2250 GHz, and a Lorentzian shape of Josephson radiation has been obtained both for equilibrium (eV very much less than kT) and nonequilibrium (eV very much greater than kT) cases. The first spectral measurements of coherent transition radiation at Test Facility Linear Accelerator at the Deutsches Elektronen-Synchrotron DESY (Hamburg) have been made and the length of electron bunches of 1.2 ps has been determined from these spectra. The comparison of Hilbert-transform spectral analysis with conventional techniques is presented.
Bandwidth and noise of submillimeter wave cuprate bicrystal Josephson junction detectors
IEEE Transactions on Applied Superconductivity, 2005
Detectors made from superconducting cuprate YBa 2 Cu 3 Ox bicrystal Josephson junctions (BJJs) on sapphire and NdGaO 3 substrates have been fabricated and characterized in the frequency band 200-900 GHz. Junctions on sapphire substrates had a normal state resistance 15 60 , and product up to 2.5 mV at = 4 2 K. Junctions on NdGaO 3 substrates had lower = 1 5 and = 0 4-0.9 mV at = 77 K. Three types of detecting devices have been investigated in both the broadband and the frequency-selective detection modes. One type was patterned with log-periodic antenna, and two others with Pt-metal double-slot antenna designed for a central frequency = 300 GHz and = 400 GHz, respectively. Measurements at = 320 GHz of the reception bandwidth 1f for a device with double-slot antenna gave a quality factor = 1 10. A low-noise cooled 1-2 GHz bandwidth amplifier enables a better sensitivity in the self-pumping frequency mixing mode, avoiding the 1/f noise. The dependence of the spectral density of noise on voltage was compared to the data for the Josephson emission linewidth obtained by the selective detector response method. Also discussed are measurements at 500 GHz of the NEP values carried out at different experimental conditions. Index Terms-High-temperature cuprate superconductors, Josephson junction, submillimeter wave devices.
High-$T_{c}$ Josephson Square-Law Detectors and Hilbert Spectroscopy for Security Applications
IEEE Sensors Journal, 2008
Among various discussed ways of explosive detection, the techniques using electromagnetic radiation are considered as having great potential and research activities are recommended in this field. To identify new threats, like liquid explosives, with low rate of false alarms, fast spectral measurements are required in a broad frequency range from microwave to terahertz. We attract attention to a great potential of high-Josephson technology in security applications and present our results in developing high-Josephson junctions for Hilbert spectroscopy and detector arrays.
Terahertz Detection and Spectroscopy Based on High-Tc Josephson Junctions
2005 18th International Conference on Applied Electromagnetics and Communications, 2005
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 -14 W/Hz 1/2 have been realized. A spectral resolution δf/f of 10 -3 has 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.