Parametric amplification of high-frequency electromagnetic radiation by josephson contacts in a resonator with own Josephson and external pumping

Background. Josephson junctions may be used for parametric amplification of high-frequency radiation, including the THz range. In this case, Josephsnon junction radiation executes the pumping function. However, the power of parametric amplification by a single junction is low (nW figures), and, thus, of great interest are arrays of Josephson junctions, which due to the technological progress in the present time allow synchronization necessary for obtaining coherent radiation of sufficient power, capable of reaching several microW for large arrays. Materials and methods. Calculation of volt-ampere characteristic and absorbed power of a junction and a junction array in a resonator were performed within a resistive model of Josephson junction using numerical methods of differential equations solving and integration. Results. The authors theoretically studied parametric generation of high-frequency electromagnetic radiation by Jospehson junctions and junction arrays in a resonator, calculated volt-ampere characteristics and absorbed power of external high-frequency radiation of a junction and a one-dimensional array of similar concatenated Josephson junctions in a resonator within a resistive model of Josephson junction at various resonator paramters and two pumping methods: 1) Josephson radiation was used as pumping radiation; 2) additional pumping by an external high-frequency field (amplification takes place on its harmonics). Conclusions. Parametric amplification by the Josephson junction in external monochromatic high-frequency radiation and in a resonator is possible in vicinity of the first Shapiro step, as well as on sub-harmonic steps that appear on volt-ampere characteristics of a junction in such system. Additional external high-frequency pumping radiation may lead to amplification not just on steps, where the Josephson frequency equals to external variable signal frequencies, but on other steps, which increases the are of parametric amplification on harmonics of high-frequency pumping radiation.