STIMULATED TRANSPARENCY OF A SUPERCONDUCTING PLATE CAUSED BY NONLINEAR-INTERACTION OF ELECTROMAGNETIC-WAVES

A nonlinear effect in the electrodynamics of hard superconductors is p redicted and theoretically studied. It is shown, that a low-frequency (LF) electromagnetic wave can pass through a superconducting plate, du e to its interaction with another wave propagating in the opposite dir ection, even at small amplitudes of the LF wave when it cannot reach t he opposite boundary of the sample without assistance. The dependence of the LF surface impedance on the amplitude of the high-frequency (hf ) wave is studied within the framework of the critical state model. Th e LF surface impedance is found to be drastically increased by the ove rlapping of the regions of wave penetration. (C) 1997 American Institu te of Physics.