Observation of Josephson plasma emission by quasiparticle injection into a Bi2Sr2CaCu2Oy single crystal

The possible first observation of Josephson plasma emission from a quasiparticle-injected Bi2Sr2CaCu2Oy(BSCCO) single crystal is reported. The quasiparticles are injected into the c-asis direction of the crystal. The emitted microwaves in the range 10 - 47GHz are detected by a superheterodyne miser technique. Three different modes of emissions are observed by biasing the current in, the hysteretic curve of the intrinsic junctions. In addition to Josephson self-emission at low bias voltage, we find the two novel emissions due to nonequilibrium effects: incoherent broadband emissions at quasiparticle branches and a sharp coherent emission in the negative resistance region at the gap edge. The latter two emissions are almost identified as Josephson plasma emissions.