Flux-flow type Josephson oscillator for millimeter and submillimeter wave region

Abstract

Fluxflowtype Josephson oscillator for millimeter and submillimeter wave region. III. Oscillation stability J. Appl. Phys. 58, 441 (1985); 10.1063/1.335643 Fluxflowtype Josephson oscillator for millimeter and submillimeter wave region. II. Modeling An oscillator which utilizes the effect of the vortex motion in long Josephson tunnel junctions, i.e., flux flow, has been presented in millimeter and submillimeter wave region. An electromagnetic wave generated by the oscillator is detected with a small tunnel junction as a detector with a refined coupling configuration. Quantitative evaluation of the detected power showed that the detected power attained the value of 10-6 W in the frequency range between 100 and 400 GHz, which is far superior to previous results. Frequency and magnetic field dependences of the present system were also measured, which showed that the output power was able to be controlled by the dc magnetic field. The present oscillator will be promising as the local oscillator in the integrated Josephson receiver systems.PACS numbers: 74.50. + r, 85.25. + k A) counter-electrode of the detector is evaporated after formation of the tunneling barrier. Upon this electrode an SiO 3302

Form and width of the spectral line of a Josephson flux-flow oscillator

“…Long Josephson oscillators operating in the flux-flow regime [2] are presently considered as possible devices for applications in superconducting millimeter-wave electronics [3]. In comparison to single fluxon oscillators they have higher output power, wider bandwidth, and easier tunability, but they have a wider linewidth [4] of the emitted radiation from the junction.…”

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

“…During the past decade, the flux-flow oscillator 1 ͑FFO͒ has been considered as the most promising local oscillator in superconducting integrated submillimeter receivers 2 and spectrometers for space-born radio astronomy and atmosphere monitoring due to its wide operational bandwidth, easy broadband tunability, and relatively high radiation power. The FFO is a long linear Josephson junction in which a viscous flow of magnetic-flux quanta ͑fluxons͒ is maintained by a dc bias current and an applied dc magnetic field.…”

“…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.…”

Coupling of Josephson flux-flow oscillators to an externalRCload

“…Some of the most important features of such a device are the following [2,3]: the output power is relatively large (0.1 − 1 µW ), the oscillator can be easily tuned in a wide band (75 − 500 GHz) by varying the bias and a magnetic field, and the emitted signal has a very narrow linewidth (130 kHz at 70 GHz [4], less than 2.1 MHz in the band 280−330 GHz [5]). As the signal generated by a local oscillator has to be coupled to a mixer or to a transmission line, in the literature different couplings to a load have been realized and studied [3,[5][6][7][8][9][10]. In some works, in particular, the FFO has been d.c. coupled to a small junction acting as a detector, or, possibly, as a mixer; in this case, the real drawback is that the junctions cannot be biased independently.…”