Nonlinear Josephson plasma waves in slabs of layered superconductors

For layered superconductors, we study the specific nonlinear Josephson plasma waves (NJPWs) propagating along thin superconducting slabs and damping away from them. Two cases are considered, when the superconductor is surrounded by either vacuum or metals. The magnetic field of the NJPW is distributed symmetrically with respect to the middle of the sample and can change its sign inside the slab. The impedance ratio of the tangential electric and magnetic field amplitudes for NJPWs can be of the order of unity. For the case of a superconductor surrounded by the vacuum, this results in a non-monotonic dispersion relation, ω(k), strongly sensitive to the NJPW amplitudes. Therefore, the “stopping light” phenomenon can be observed at frequencies where dω(k)/dk = 0. Resonance excitations of the NJPWs should produce anomalies in the amplitude dependence of the reflectivity and transmissivity of the incident THz waves, which could be useful for THz devices. Animations illustrating the results presented here, are available online at dml.riken.go.jp/nonlinear.