Three-terminal stand-alone superconducting terahertz emitter

Abstract

We report on the electrothermal behavior and the terahertz emission properties of a stand-alone Bi2Sr2CaCu2O8 intrinsic Josephson junction stack contacted in a three-terminal configuration. One terminal is used as a collective ground while the other two, contacting the stack from its right and left side, allow to vary the current injection profile. At high bias, a hot spot forms in the stack. Its appearance and position can be controlled by varying the ratios of the injected currents. Depending on this ratio, the emitted power can vary by an order of magnitude. Further, for a given total injection current, the device allows to vary the emission frequency on a 10% level by altering the injection profile. The overall tunability of the emission frequency, varying also the total bias current, is on the order of 20%.

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

“…For B x = 0 the emission is strong for I between 10 and 20 mA and T bath between 10 and 40 K. One notes short period oscillations in P e which presumably are extrinsic in origin. These oscillations have been observed before 28,35,66 . Apart from that the plots clearly show that, for B x = 5.9 mT, over a wide range of currents and bath temperatures P e has increased significantly, in some of the stripe-like regions up to a factor of 2.7.…”

“…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 . In fact, recent results showed that there is a strong interaction 28 . Further, cooling has been improved by sandwiching the stacks between substrates with high thermal conductivity.…”

Tuning THz emission properties of Bi2Sr2CaCu2O8+δintrinsic Josephson junction stacks by charge carrier injection

“…The stack geometry is sketched in figure 1. The sample preparation is similar to the one described in [26]. First, the crystal is glued with epoxy onto a Si substrate.…”

Improved excitation mode selectivity of high-Tc superconducting terahertz emitters

“…The local temperature distributions TðrÞ of the IJJ mesa devices have been measured in detail, and the results have been discussed in comparison with theoretical studies. [14][15][16][40][41][42][43][44][45]51,[63][64][65][66][78][79][80] These studies concluded that the spontaneous formation of a local temperature instability known as a hot spot can occur in the IJJ-THz emitter device due to both the quasi-two-dimensional thermal and electrical conductivities, the latter yielding a semiconducting-like temperature dependence of the c-axis normal state resistivity for under-doped Bi2212 single crystals. Previous studies revealed that a hot spot, within which the local temperature TðrÞ > T c , acts as a shunt resistance inserted parallel to the 0021-8979/2018/124(3)/033901/9/$30.00…”