Abstract:
The paper presents the results of developing a new type of oscillators based on arrays of Josephson junctions included in a superconducting coplanar line. Subterahertz range (200–700 GHz) oscillators based on arrays of tunnel Josephson junctions Nb–AlO$_x$–Nb and Nb–AlN–NbN shunted by a thin-film resistor are investigated. Several series of oscillator’s samples are manufactured, including arrays of 100, 200, 350 and 600 Josephson junctions with an area of 2.8 $\mu$m$^2$ and 4.2 $\mu$m$^2$. Studies of superconducting oscillators using integrated radiation detectors have shown the possibility of frequency tuning in the entire operating range up to 700 GHz with an output power of up to 0.4 $\mu$W for an array of 600 junctions with a tunnel current density of 7 kA/cm$^2$, which is sufficient for applications in superconducting integrated receivers. The use of a superconducting harmonic mixer made it possible to measure the radiation spectrum of a superconducting oscillator at frequencies up to 700 GHz in the frequency stabilization mode and to implement the phase-locked loop mode. Further prospects in the field of developing superconducting oscillators in the terahertz range are discussed.
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