Terahertz Applications of Hilbert-Transform Spectral Analysis

Divin, Y.Y.; Snezhko, A.; Lyatti, M.; Poppe, U.; Pavlovskiy, V. V.

doi:10.1109/tasc.2014.2318314

Cited by 6 publications

(4 citation statements)

References 14 publications

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“…At high input frequencies f in from 16 to 19.5 GHz, additional strong lines with n=18 are observed accompanied by some weak lines with other multiplication numbers. More detailed HTSA of THz multipliers based on GaAs Schottky diodes and GaAs/AlAs superlattices one can find elsewhere [53].…”

Section: Polychromatic Thz Radiation Of Frequency Multipliersmentioning

confidence: 99%

Terahertz Josephson spectral analysis and its applications

Snezhko

Gundareva

Lyatti

et al. 2017

Supercond. Sci. Technol.

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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 IcRn 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.

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Section: Polychromatic Thz Radiation Of Frequency Multipliersmentioning

confidence: 99%

Terahertz Josephson spectral analysis and its applications

Snezhko

Gundareva

Lyatti

et al. 2017

Supercond. Sci. Technol.

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“…In high-energy physics, it was possible to substantiate and partially implement high-T c JJs for spectral analysis of transition radiation from relativistic electron bunches in linear accelerators [10] and cyclotron electron emission from high-temperature plasma in tokamaks [11]. Previous studies of output sub-THz and THz radiation from commercial sources [12][13][14][15][16] with high-T c JJs have paved the way for the spectral characterization of new THz sources based on quantum cascade lasers (QCLs) [17,18]. Recently, using high-T c JJs, subterahertz spectral lines have been found in the emission of free-running THz quantum cascade lasers (QCLs) due to difference-frequency generation (DFG) in the QCL active region [19].…”

Section: Introductionmentioning

confidence: 99%

“…The latter circumstance is for verification in various configurations of high-T c JJs with proper tuning of relevant parameters of the junctions. Previously, Josephson bicrystal junctions, consisting of two c-oriented YBa 2 Cu 3 O 7−x thin-film electrodes, were mainly used for spectroscopic purposes [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The simple bicrystal junction, where the c-axis epitaxial films grow on each part of the bicrystal substrate, forms an artificial bicrystal boundary by the coalescence of two misoriented c-axis thin-film parts.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Absorption Spectroscopy in Bicrystal Josephson Junctions Formed from Mutually Tilted c-Axes YBa2Cu3O7−x Films

Divin

2023

Applied Sciences

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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 of the oxygen content. In addition, the fine structure of the absorption spectrum appears at frequencies near 4.6 THz. Significant absorption near 2.3 THz may be due to effects associated with the second Josephson harmonic or second-order nonlinearity of the susceptibility in YBa2Cu3O7−x. This work paves the way towards probing collective modes in high-Tc materials in situ using the Josephson oscillations.

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“…One is to improve the transmission efficiency of the ECE transmission line and other is to have a broad band ECE measurement instrument with low NEP detection system. We propose a new type of a THz spectrum analyzer, based on a high-T c superconducting Josephson junction with low NEP-values [2] …”

Section: Introductionmentioning

confidence: 99%

New approach to ECE measurements based on Hilbert-transform spectral analysis

Pandya

Divin

2015

EPJ Web of Conferences

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Abstract. Spectroscopy of Electron Cyclotron Emission (ECE) has been established asadequate diagnostic technique for fusion research machines. Among various instruments for ECE diagnostics, only Fourier-transform spectrometers with Martin-Puplett interferometers can measure electron cyclotron radiation in a broadband frequency range from 70 to 1000 GHz. Before these measurements, a complete system including a frontend radiation collector, a transmission line, an interferometer and a radiation detector should be absolutely calibrated. A hot/cold calibration source and data-averaging technique are used to calibrate the total ECE diagnostic system. It takes long time to calibrate the ECE system because of the low power level of the calibration source and high values of the noise equivalent power (NEP) of the detection system. A new technique, Hilbert-transform spectral analysis, is proposed for the ITER plasma ECE spectral measurements. An operation principle, characteristics and advantages of the corresponding Hilbert-transform spectrum analyser (HTSA) based on a high-T c Josephson detector are discussed. Due to lower NEP-values of the Josephson detector, this spectrum analyser might demonstrate shorter calibration times than that for the Martin-Puplett interferometer.

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Terahertz Applications of Hilbert-Transform Spectral Analysis

Cited by 6 publications

References 14 publications

Terahertz Josephson spectral analysis and its applications

Terahertz Josephson spectral analysis and its applications

Terahertz Absorption Spectroscopy in Bicrystal Josephson Junctions Formed from Mutually Tilted c-Axes YBa2Cu3O7−x Films

New approach to ECE measurements based on Hilbert-transform spectral analysis

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