110 research outputs found
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.Comment: 6 pages, 5 figures, supplementary information include
Coherent THz emission of Bi_2Sr_2CaCu_2O_8 intrinsic Josephson junction stacks in the hot spot regime
We report on THz emission measurements and low temperature scanning laser
imaging of Bi_2Sr_2CaCu_2O_8 intrinsic Josephson junction stacks. Coherent
emission is observed at large dc input power, where a hot spot and a standing
wave, formed in the "cold" part of the stack, coexist. By varying the hot spot
size the cavity resonance frequency and the emitted radiation can be tuned. The
linewidth of radiation is much smaller than expected from the quality factor of
the cavity mode excited. Thus, an additional mechanism of synchronization seems
to play a role, possibly arising from nonequilibrium processes at the hot spot
edge.Comment: 4.1 pages, 5 figure
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