Hot spots and waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks   -a study by Low Temperature Scanning Laser Microscopy
  Recently, it has been shown that large stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8 emit synchronous THz radiation, the synchronization presumably triggered by a cavity resonance. To investigate this effect we use Low Temperature Scanning Laser Microscopy to image electric field distributions. Apart from verifying the appearance of cavity modes at low bias we find that, in a high input power regime, standing-wave patterns are created through interactions with a hot spot, possibly pointing to a new mode of generating synchronized radiation in intrinsic Josephson junction stacks. 
H.B. Wang, S. Gu\'enon, J. Yuan, A. Iishi, S. Arisawa, T. Hatano, T.   Yamashita, D. Koelle, R. Kleiner