Optimization of the Phase-Locked Flux-Flow Oscillator for the submm Integrated Receiver

Koshelets, V. P.; Дмитриев, П. Н.; Ermakov, A.B.; Соболев, А. С.; Torgashin, M. Yu.; Kurin, V. V.; Pankratov, A. L.; Mygind, J.

doi:10.1109/tasc.2005.850140

Cited by 46 publications

(39 citation statements)

References 15 publications

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“…The dynamical and fluctuational properties of the FFO have been intensively studied both experimentally and theoretically. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In contrast to many other types of oscillators, the FFO fluctuations are mainly caused by internal wideband sources, such as thermal and shot noise, that result in a spectral line of emission with nearly perfect Lorentzian shape. The power in the so-called "wings" decreases much slower with frequency offset from the carrier than the Gaussian shaped spectral line obtained when external noise sources are dominant.…”

Section: Introductionmentioning

confidence: 99%

Influence of surface losses and the self-pumping effect on current-voltage characteristics of a long Josephson junction

et al. 2007

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We have numerically investigated the dynamics of a long linear Josephson tunnel junction with overlap geometry. Biased by a direct current ͑dc͒ and an applied dc magnetic field, the junction has important applications as tunable high frequency oscillator ͓flux-flow oscillator ͑FFO͔͒ in the millimeter and submillimeter range. The study is performed in the frame of a modified sine-Gordon model, which includes surface losses, self-pumping effect, and in an empirical way the superconducting gap. The electromagnetic coupling to the environment is modeled by a simple resistor-capacitor load ͑RC load͒ placed at both ends of the FFO. In our model, the damping parameter depends both on the spatial coordinate and on the amplitude of the ac voltage. In order to find the dc current-voltage curves, the damping parameter has to be calculated self-consistently by successive approximations and time integration of the perturbed sine-Gordon equation. The modified model gives better qualitative agreement with experimental results than the conventional perturbed sine-Gordon model.

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Section: Introductionmentioning

confidence: 99%

Influence of surface losses and the self-pumping effect on current-voltage characteristics of a long Josephson junction

et al. 2007

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“…Refs. [65,69,[104][105][106]). The layouts of the FFO samples were optimized for coupling to load by using the sharpened edge geometries: the width 16 μm in the central region was degraded linearly to about 1 μm on a distance 40 μm (30 μm for the 60 μm junction) from either end.…”

Section: Comparison To Experimental Resultsmentioning

confidence: 99%

Josephson flux-flow oscillator: The microscopic tunneling approach

2017

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Citation: GULEVICH, D.R., KOSHELETS, V.P. and KUSMARTSEV, F.V., 2017.Josephson flux-flow oscillator:The microscopic tunneling approach.Physical Review B, 96 (2), 024515-1 -024515-12.Additional Information:• We elaborate a theoretical description of large Josephson junctions which is based on Werthamer's microscopic tunneling theory. The model naturally incorporates coupling of electromagnetic radiation to the tunnel currents and, therefore, is particularly suitable for description of the self-coupling effect in Josephson junction. In our numerical calculations we treat the arising integro-differential equation, which describes temporal evolution of the superconducting phase difference coupled to the electromagnetic field, by the Odintsov-Semenov-Zorin algorithm. This allows us to avoid evaluation of the time integrals at each time step while taking into account all the memory effects. To validate the obtained microscopic model of large Josephson junction we focus our attention on the Josephson flux-flow oscillator. The proposed microscopic model of flux-flow oscillator does not involve the phenomenological damping parameter, rather the damping is taken into account naturally in the tunnel current amplitudes calculated at a given temperature. The theoretically calculated current-voltage characteristics is compared to our experimental results obtained for a set of fabricated flux-flow oscillators of different lengths.

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“…For the harmonic mixer, the synthesizer signal is the pumping, and the power coming from FFO is the desired signal. Hence, the level of the FFO power required for operation of the harmonic mixer with a sufficiently high signal-to-noise ratio does not exceed 5 − 10% of I g [11]. Significant excess over this level at some frequencies is not a problem since the harmonic mixer operates in a strongly nonlinear regime, and information is contained in the frequency (not the amplitude) of the converted signal.…”

Section: Results Of Measuring the Characteristics Of The Receivermentioning

confidence: 99%

“…Their use allows us to realize phase locking of FFO in all regimes, similarly to the procedure of manual tuning [11]. Besides, the IRTECON system makes it possible to optimize the operation of the "harmonic mixer-PLL system" cluster.…”

Section: Results Of Measuring the Characteristics Of The Receivermentioning

confidence: 99%

Integrated superconducting spectrometer for atmosphere monitoring

Koshelets

Дмитриев

Ermakov

et al. 2005

Radiophys Quantum Electron

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The results of the development of sub-mm Superconducting Integrated Receiver (SIR) for monitoring of the Earth's atmosphere from high-altitude balloons are presented. The microchip of the superconducting integrated receiver comprising local oscillator based on the long Josephson junction (flux flow oscillator, FFO) is developed and successfully tested. The receiver noise temperature as low as 200 K is measured at a frequency of 650 GHz. The possibility to phase-lock FFO to the reference oscillator, which is vitally important for spectrometer operation, is demonstrated. To ensure the possibility of remote tuning of a phase-locked (PL) SIR onboard a balloon, a number of approaches for the PL SIR automatic computer control are developed and tested. New modifications of the superconducting local oscillator (FFO) are developed, fabricated and tested. The FFO design is optimized for the integrated spectrometer. The FFO linewidth is studied at frequencies of up to 700 GHz using a specially developed technique. A free-running linewidth between 9 and 2 MHz is measured in the frequency range from 500 to 700 GHz. As a result, the spectral ratio of the phased-locked FFO ranges from 35 to 90%. The effect of FFO linewidth imperfections on the retrieval procedure of the atmosphere gas spectra is studied.

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Optimization of the Phase-Locked Flux-Flow Oscillator for the submm Integrated Receiver

Cited by 46 publications

References 15 publications

Influence of surface losses and the self-pumping effect on current-voltage characteristics of a long Josephson junction

Influence of surface losses and the self-pumping effect on current-voltage characteristics of a long Josephson junction

Josephson flux-flow oscillator: The microscopic tunneling approach

Integrated superconducting spectrometer for atmosphere monitoring

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