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

By S. Savel’ev, V. Yampol’skii, A. Rakhmanov, Franco Nori. 2009

150 citations recorded by the source corpus.

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, ωJ, 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 ωJ, 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 tunneling of fluxons through stacks of Josephson junctions. Moreover, the nonlocal sine-Gordon equation for Josephson vortices is reviewed. We discuss the Cherenkov and transition radiations of the Josephson plasma waves produced by moving Josephson vortices, either in a single Josephson junction or in layered superconductors. Furthermore, the expression for the Cherenkov cone of the excited Josephson plasma waves is derived. We also discuss the problem of coherent radiation (superradiance) of the THz waves by exciting uniform Josephson oscillations. The effects reviewed here could be potentially useful for sub-THz and THz emitters, filters and detectors.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/40e2e8e7f68f8646169762d6038d0d4e0b578bcf

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Citations in the corpus

• Terahertz surface plasmonic waves: a review (2020, background): “Due to resonant excitation of SJPWs, the reflectivity of the incident wave depends sharply on its frequency and incident angle, which is quite useful for filtering and detecting THz and sub-THz radiation using layered superconductors.93 Further details on the basic mechanisms and potential applicati”
• Roadmap on plasmonics (2018, unknown): “Together, the Josephson inductance and the diamagnetism-related inductance allow for the propagation of plasma waves inside the junctions, known as Josephson plasma waves [80].”