Linewidth dependence of coherent terahertz emission from Bi2Sr2CaCu2O

Mengyue Li

¹

,

Jie Yuan

²

,

Nickolay V. Kinev

³

et al.

Abstract

We report on measurements of the linewidth ∆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 ∆f may be below 1 GHz -much smaller than expected from a purely cavity-induced synchronization. While at low bias we found ∆f to be not smaller than ∼ 500 MHz, at high bias, where a hotspot coexists with regions which are still superconducting, ∆f turned out to be as narrow as 23 MHz. We attribute this to the hotspot acting as a synchronizing element. ∆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.

Direct imaging of hot spots in Bi2Sr2CaCu2O8+δ mesa terahertz sources

“…5,6 Furthermore, it is possible that hot spots form a shunt between the stacked Josephson junctions, thereby promoting their synchronization. 5,11 This is consistent with studies, which find a narrower THz radiation line width from mesas with comparatively high DC power dissipation. 12 Furthermore, it was observed that mesas covered with thick electrodes that homogenize the temperature do not emit THzradiation.…”

Josephson flux-flow oscillator: The microscopic tunneling approach

“…To accommodate multiple fluxons and achieve a flux-flow regime, the length of the Josephson junction used as a FFO exceeds the Josephson penetration length by a large factor. The potential of FFO for practical applications has been justified by development of a superconducting integrated receiver (SIR) [65,66] which was successfully used in remote heterodyne spectroscopy of the Earth atmosphere on board of a high-altitude balloon [67,68], as well as first spectral measurements of THz radiation emitted from intrinsic Josephson junction stacks (BSCCO mesa) at frequencies up to 750 GHz [69,70].…”

Three-Dimensional Simulations of the Electrothermal and Terahertz Emission Properties ofBi2Sr2CaCu2Rudau1, Wieland2, Langer3 et al. 2016Phys. Rev. Applied300270View full textAdd to dashboardCite

“…The THz emission properties of the IJJ stacks are affected by the hot spot. For example, it has been found that the linewidth of radiation is much narrower in the high-bias regime than at low bias 12,60 . Other properties such as the emission frequency seem to be basically independent of the hot spot position, leading to some debate as to whether the hot spot is helpful for radiation or just coexists with the radiating regions 20,22,23 .…”