DIRECT OBSERVATION OF JOSEPHSON SELF-RADIATION IN BI2SR2CA2CU3OY BREAK JUNCTIONS ABOVE 77-K

We have directly observed the Josephson self-radiation emitted from a Bi2Sr2Ca2Cu3Oy break junction at receiver frequencies f(REC) = 11 and 47 GHz above liquid-nitrogen temperature. The results on the current-v oltage characteristics, the dV/dI vs I curves, the harmonic Josephson self-radiation, and the dependence of critical current on microwave se lf-radiation power are well interpreted in terms of the current biased resistively shunted junction model. The maximum first-harmonic self-r adiation powers at receiver frequencies f(REC) = 11 and 47 GHz were P( I) = 3 X 10(-13) and P(I) = 1 X 10(13) W at 77 K, respectively.