High-power terahertz electromagnetic wave emission from high-Tc superconducting Bi2Sr2CaCu2O8+δ mesa structures

In this paper, we report intense electromagnetic wave emissions generated by the rectangular mesa structure of intrinsic Josephson junctions with high-T-c superconducting Bi2Sr2CaCu2O8+delta. The radiated power is an order of magnitude stronger than that of the previously observed power of a few mu W. Two emission regions, reversible (R-type) and irreversible (IR-type), with comparable intensities can be observed at different I-V curve locations in the same mesa. We find peculiar temperature dependences of the emission power in both the R-and IR-type radiations, suggesting that a non-equilibrium thermodynamic state may be realized through the dc input current. The R-type emission is quite stable, whereas the IR-type emission is rather unstable. Although the emitted frequency for both cases obey the cavity resonance conditions, this sharp contrast in emission stability is indicative of two different states in a multi-stacked intrinsic Josephson junction system. (C) 2011 Optical Society of America