Radiation due to Josephson Oscillations in Layered Superconductors

Bulaevskiǐ, L. N.; Koshelev, A. E.

doi:10.1103/physrevlett.99.057002

Cited by 120 publications

(140 citation statements)

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“…To fit experiment, we assume TM z n00 modes, which oscillate in position with integral multiples of half-wavelengths along the mesa widths [2,8,9,10]. In rectangular source coordinates (x ′ , y ′ , z ′ ),…”

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confidence: 99%

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Angular Dependence of the Radiation Power of a Josephson STAR-emitter

Klemm

Kadowaki

2010

J Supercond Nov Magn

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We calculate the angular dependence of the power of stimulated terahertz amplified radiation (STAR) emitted from a dc voltage applied across a stack of intrinsic Josephson junctions. During coherent emission, we assume a spatially uniform ac Josephson current density in the stack acts as a surface electric current density antenna source, and the cavity features of the stack are contained in a magnetic surface current density source. A superconducting substrate acts as a perfect magnetic conductor with H ||,ac = 0 on its surface. The combined results agree very well with recent experimental observations. Existing Bi2Sr2CaCu2O 8+δ crystals atop perfect electric conductors could have Josephson STAR-emitter power in excess of 5 mW, acceptable for many device applications.PACS numbers: 07.57. Hm, 74.50.+r, 85.25.Cp At present, broad-band terahertz (THz) electromagnetic (EM) waves generated from femtosecond laser pulses and monochromatic THz waves generated by laser mixing, parametric resonance techniques, and quantum cascade lasers, etc., are the most common THz sources [1]. But these techniques are not cost effective in the "THz gap" region 0.1-10 THz required for many important applications. After many years of effort, by application of a static voltage across the intrinsic Josephson junctions in Bi 2 Sr 2 CaCu 2 O 8+δ (BSCCO) mesas, coherent radiation power of 0.5 µW was achieved [2]. The same technique on different samples since led to radiation power of 5 µW and an output efficiency of 3×10 −4 [3]. This is an exciting development, as the "THz gap" may soon be filled.In both experiments, the onset of the intense, coherent THz radiation occurs in or near to the region in the current-voltage (I − V ) characteristic of negative differential resistance (NDR), as for the Gunn effect in Ge [4]. In the absence of more precise information, we assume that the stack of Josephson junctions acts partly as a cavity, in order to amplify the coherent radiation at the fundamental Josephson angular frequency ω J and possibly its harmonics, and partly as a conductor with an ac Josephson current, J ac (x ′ , t) = J(x ′ ) ∞ n=1 a n sin(nω J t), where ω J = 2eV 0 /(Nh) is the Josephson angular frequency, V 0 is the dc voltage applied across the coherent stack of N ≈ 10 3 junctions, e is the electric charge,h is the Planck constant divided by 2π, and a n is the relative amplitude of the nth harmonic of the intrinsic ac Josephson current. The effective radiation sources at the mesa edges are respectively the surface magnetic current M S arising from the electric field in the cavity generated by the non-uniform part of J ac (x ′ , t) [6], and the surface electric current J S arising from the uniform part of J ac (x ′ , t), as sketched in Fig. 1 (a). These sources are obtained from the Faraday and Ampère boundary conditions, respectively [5,6], as used previously [7,8,9,10,11]. We first assume the mesa is suspended in vacuum. In Lorentz gauge, the vector potentials from the respective radiation sources are [5,6],ǫ, inside and outside ...

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“…1 (a). These sources are obtained from the Faraday and Ampère boundary conditions, respectively [5,6], as used previously [7,8,9,10,11]. We first assume the mesa is suspended in vacuum.…”

mentioning

confidence: 99%

Angular Dependence of the Radiation Power of a Josephson STAR-emitter

Klemm

Kadowaki

2010

J Supercond Nov Magn

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“…This dependence has resonance peaks at Ωl x ≈ 2πn with amplitudes rapidly decreasing with n. Expanding the value ψ rad in Eq. (247) near the resonance, we find the dependence of the THz radiation on the number of junctions in the SJJ and the thickness L x , which can be conveniently presented in the form [141],…”

Section: B Theory Of Superradiance In the Resistive Modementioning

confidence: 99%

“…A detailed derivation of the boundary conditions to the latter equation is presented in Refs. 141,143. Under the assumptions formulated above, these conditions can be written in the form,…”

Section: B Theory Of Superradiance In the Resistive Modementioning

confidence: 99%

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Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear and quantum phenomena

et al. 2010

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The recent growing interest in terahertz (THz) and sub-THz science and technology is due to its many important applications in physics, astronomy, chemistry, biology, and medicine, including THz imaging, spectroscopy, tomography, medical diagnosis, health monitoring, environmental control, as well as chemical and biological identification. We review the problem of linear and nonlinear THz and sub-THz Josephson plasma waves in layered superconductors and their excitations produced by moving Josephson vortices. We start by discussing the coupled sine-Gordon equations for the gauge-invariant phase difference of the order parameter in the junctions, taking into account the effect of breaking the charge neutrality, and deriving the spectrum of Josephson plasma waves.We also review surface and waveguide Josephson plasma waves. The spectrum of these waves is presented, and their excitation is discussed. We review the propagation of weakly nonlinear Josephson plasma waves below the plasma frequency, ω J , which is very unusual for plasma-like excitations.In close analogy to nonlinear optics, these waves exhibit numerous remarkable features, including a self-focusing effect, and the pumping of weaker waves by a stronger one. In addition, an unusual stop-light phenomenon, when ∂ω/∂k ≈ 0, caused by both nonlinearity and dissipation, can be observed in the Josephson plasma waves. At frequencies above ω J , the current-phase nonlinearity can be used for transforming continuous sub-THz radiation into short, strongly amplified, pulses.We also present quantum effects in layered superconductors, specifically, the problem of quantum MQT -macroscopic quantum tunnelling.z-axis is directed across the layers; y-axis is directed along the magnetic field.4

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Intrinsic Josephson Junctions in High Temperature Superconductors

Kleiner¹,

Wang²

2019

Fundamentals and Frontiers of the Josephson Effect

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Radiation due to Josephson Oscillations in Layered Superconductors

Cited by 120 publications

References 17 publications

Angular Dependence of the Radiation Power of a Josephson STAR-emitter

Angular Dependence of the Radiation Power of a Josephson STAR-emitter

Terahertz Josephson plasma waves in layered superconductors: spectrum, generation, nonlinear and quantum phenomena

Intrinsic Josephson Junctions in High Temperature Superconductors

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