Unusual linewidth dependence of coherent THz emission measured from intrinsic Josephson junction stacks in the hot-spot regime

M. Y. Li; J. Yuan; N. Kinev; J. Li; B. Gross; S. Guenon; A. Ishii; K. Hirata; T. Hatano; D. Koelle; R. Kleiner; V. P. Koshelets; H. B. Wang; P. H. Wu

doi:10.1103/physrevb.86.060505

arXiv · 1206.2125

Unusual linewidth dependence of coherent THz emission measured from intrinsic Josephson junction stacks in the hot-spot regime

M. Y. Li·J. Yuan·N. Kinev·J. Li·B. Gross·S. Guenon·A. Ishii·K. Hirata·T. Hatano·D. Koelle·R. Kleiner·V. P. Koshelets·H. B. Wang·P. H. Wu

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Abstract

We report on measurements of the linewidth {\Delta}f of THz radiation emitted from intrinsic Josephson junction stacks, using a Nb/AlN/NbN integrated receiver for detection. Previous resolution limited measurements indicated that {\Delta}f may be below 1 GHz - much smaller than expected from a purely cavity-induced synchronization. While at low bias we found {\Delta}f to be not smaller than ? 500 MHz, at high bias, where a hotspot coexists with regions which are still superconducting, {\Delta}f turned out to be as narrow as 23 MHz. We attribute this to the hotspot acting as a synchronizing element. {\Delta}f decreases with increasing bath temperature, a behavior reminiscent of motional narrowing in NMR or ESR, but hard to explain in standard electrodynamic models of Josephson junctions.

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M. Y. Li, J. Yuan, N. Kinev, J. Li, B. Gross, S. Guenon, A. Ishii, K. Hirata, T. Hatano, D. Koelle, R. Kleiner, V. P. Koshelets, H. B. Wang, P. H. Wu. 2012-06-11. Unusual linewidth dependence of coherent THz emission measured from intrinsic Josephson junction stacks in the hot-spot regime. https://doi.org/10.1103/physrevb.86.060505

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