On-chip spectroscopic detection of terahertz radiation emitted from a quasiparticle-injected nonequilibrium superconductor using a high-Tc Josephson junction

Kume, E.; Iguchi, Ienari; Takahashi, Hitomi

doi:10.1063/1.125157

Cited by 24 publications

(20 citation statements)

References 16 publications

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“…1,2 Much effort has been made to stimulate powerful radiations, first using artificial Josephson junction arrays [3][4][5][6][7][8][9][10][11] and later on Josephson junctions inherent in cuprate high-T c superconductors of layered structures. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] The latter have obvious advantages since the junctions are homogeneous at the atomic scale guaranteed by the high quality of single crystals, and the superconductivity gap is large, typically of tens of meV, which in principle permits the frequency to cover the whole range of the terahertz ͑THz͒ band, a very useful regime of EM waves still lacking of compact solid-state generators. 27,28 An experimental breakthrough was achieved in 2007.…”

Section: Introductionmentioning

confidence: 99%

Cavity phenomena in mesas of cuprate high-Tcsuperconductors under voltage bias

Lin

2009

Phys. Rev. B

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Modeling a single crystal of cuprate high-T c superconductor, such as Bi 2 Sr 2 CaCu 2 O 8+␦ , as a stack of intrinsic Josephson junctions, we formulate explicitly the cavity phenomenon of plasma oscillations and electromagnetic ͑EM͒ waves in mesas of cylindrical and annular shapes. The phase differences of the junctions are governed by the inductively coupled sine-Gordon equations, with the Neumann-type boundary condition for sample thickness much smaller than the EM wavelength, which renders the superconductor single crystal a cavity. Biasing a dc voltage in the c direction, a state with Ϯ kinks in the superconductivity phase difference piled up alternatively along the c axis is stabilized. The Ϯ phase kinks provide interlock between superconductivity phases in adjacent junctions, taking the advantage of huge inductive couplings inherent in the cuprate superconductors, which establishes the coherence across the whole system of more than ϳ600 junctions. They also permit a strong coupling between the lateral cavity mode of the transverse Josephson plasma and the c-axis bias, and enhance the plasma oscillation significantly at the cavity modes which radiates EM waves in the terahertz band when the lateral size of mesa is set to tens of micrometers. It is discussed that the cavity mode realized in a very recent experiment using a cylindrical mesa can be explained by the present theory. In order to overcome the heating effect, we propose to use annular geometry. The dependence of frequency on the radius ratio is analyzed, which reveals that the shape tailor is quite promising for improving the present technique of terahertz excitation. The annular geometry may be developed as a waveguide resonator, mimicking the fiber lasers for visible lights.

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Section: Introductionmentioning

confidence: 99%

Cavity phenomena in mesas of cuprate high-Tcsuperconductors under voltage bias

Lin

2009

Phys. Rev. B

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“…[13,14,15,16,17,18,19] In spite of these works, it is still lack of clear evidence of coherent radiation. Radiation from BSCCO with injection of quasiparticles has been reported [20,21,22,23,24]. Alternatively, the terahertz radiation without a magnetic field has also been attempted [25,26,27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Phase dynamics in intrinsic Josephson junctions and their electrodynamics

Lin

2009

Phys. Rev. B

174

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We present a theoretical description of the phase dynamics and its corresponding electrodynamics in a stack of inductively coupled intrinsic Josephson junctions of layered high-Tc superconductors in the absence of an external magnetic field. Depending on the spatial structure of the gauge invariant phase difference, the dynamic state is classified into: state with kink, state without kink, and state with solitons. It is revealed that in the state with phase kink, the plasma is coupled to the cavity and the plasma oscillation is enhanced. In contrast, in the state without kink, the plasma oscillation is weak. It points a way to enhance the radiation of electromagnetic from high-Tc superconductors. We also perform numerical simulations to check the theory and a good agreement is achieved. The radiation pattern of the state with and without kink is calculated, which may serve as a fingerprint of the dynamic state realized by the system. At last, the power radiation of the state with solitons is calculated by simulations. The possible state realized in the recent experiments is discussed in the viewpoint of the theoretical description. The state with kink is important for applications including terahertz generators and amplifiers.

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“…Injection of quasiparticles into high-T c superconductors can also generate THz plasma oscillation and thus EM radiation. The basic idea is as follows [155]: In experiments [156][157][158][159][160], Iguchi et al injected quasiparticles into high-T c superconductors such as YBCO and BSCCO by a tunneling junction (Cu/I/S tunneling junction, S denotes superconductors and I denotes insulators). The radiation is detected by a superheterodyne mixer.…”

Section: V2 Radiation Caused By Quasiparticle Injectionmentioning

confidence: 99%

Phase dynamics in a stack of inductively coupled intrinsic Josephson junctions and terahertz electromagnetic radiation

Hu¹,

Lin²

2010

Supercond. Sci. Technol.

115

110

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The Josephson effect is a phenomenon of current flow across two weakly linked superconductors separated by a thin barrier, i.e. Josephson junction, associated with coherent quantum tunneling of Cooper pairs. Many novel phenomena appear due to the nonlinear property of the Josephson effect, such as Shapiro steps in dc current-voltage (IV) characteristics of a Josephson junction under microwave shining, which can be used as a voltage standard. The Josephson effect also provides a unique way to generate high-frequency electromagnetic (EM) radiation by dc bias voltage as the inverse process of the Shapiro step. The discovery of cuprate high-T c superconductors accelerated the effort to develop novel source of EM waves based on a stack of atomically dense-packed intrinsic Josephson junctions (IJJs), since the large superconductivity gap covers the whole terahertz (THz) frequency band. Very recently, strong and coherent THz radiations have been successfully generated from a mesa structure of Bi 2 Sr 2 CaCu 2 O 8+ single crystal which works both as the source of energy gain and as the cavity for resonance. This experimental breakthrough posed a challenge to theoretical study on the phase dynamics of stacked IJJs, since the phenomenon cannot be explained by the known solutions of the sine-Gordon equation so far. It is then found theoretically that, due to huge inductive coupling of IJJs produced by the nanometer junction separation and the large London penetration depth of order of m  of the material, a novel dynamic state is stabilized in the coupled sine-Gordon system, in which   kinks in phase differences are developed responding to the standing wave of Josephson plasma and are stacked alternately in the c -axis.This novel solution of the inductively coupled sine-Gordon equations captures the important features of experimental observations. The theory predicts an optimal radiation power larger than the one observed in recent experiments by orders of magnitude, and thus suggests the technological relevance of the phenomena.

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On-chip spectroscopic detection of terahertz radiation emitted from a quasiparticle-injected nonequilibrium superconductor using a high-Tc Josephson junction

Cited by 24 publications

References 16 publications

Cavity phenomena in mesas of cuprate high-Tcsuperconductors under voltage bias

Cavity phenomena in mesas of cuprate high-Tcsuperconductors under voltage bias

Phase dynamics in intrinsic Josephson junctions and their electrodynamics

Phase dynamics in a stack of inductively coupled intrinsic Josephson junctions and terahertz electromagnetic radiation

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