Observation of Nonequilibirum Microwave Emission from dc-Biased High Tc YBa2Cu3O7-y Junctions

HTS Josephson plasma oscillator

“…When several branches were traced out, it appeared sequentially. These emissions are qualitatively different from conventional Josephson self-emission and are quite similar to those observed by tunnel injection of quasiparticles into YBCO, EBCO and BSCCO films given above [6][7][8] and are considered to be the incoherent plasmon emission arising from the electron-plasmon interaction. The emission of plasmons leads to microwave emission into free space.…”

“…The results for microwave emissions detected at 11.6-47 GHz were qualitatively similar among YBCO, EBCO and BSCCO samples. Figure 3 and 4 show typical results for the microwave emissions from quasiparticleinjected YBCO [6,7] and BSCCO [12] films, respectively, at the receiver frequency 47 GHz at different temperatures. At low temperatures (T = 4.2 K-10 K), the detected power increased almost linearly with increasing injection current, not being proportional to the injected power, suggesting the incoherent emission of microwaves.…”

“…Curves B 1 and B 2 correspond to the relatively weak injection case for which the Josephson plasma peak is clear, while curves C 1 and C 2 correspond to the strong injection case for which it is washed away. Experimentally, several reports suggesting Josephson plasma emission appeared quite recently [6][7][8][9][10][11][12]. The intensive quasiparticle injection into a c-axis oriented YBCO film induced a broad range of microwave emissions, while that into the c-axis direction of a BSCCO crystal induced both broadband and sharp nonequilibrium emissions.…”

“…We here present a brief review of these novel microwave emissions from a quasiparticle-injected nonequilibrium high-T c superconductor observed recently [6][7][8][9][10][11][12]…”