Generation of tunable terahertz radiation using Josephson vortices: Transition and Cherenkov radiation

We describe proposal on how to control the THz radiation generated by fast moving Josephson vortices in spatially modulated (either along the c-axis or the ab-plane) samples of Bi2Sr2CaCu2O8+δ and related superconducting compounds. We show that the JVs moving in a subset of slightly weaker junctions can generate out-of-ab-plane and outside-the-cone Cherenkov radiation. The ab-plane modulation of superconducting properties (achieved, for instance, by ion irradiation lithography) can result in transition radiation within certain frequency windows, i.e., allowing the design of tunable THz emitters and THz photonic crystals.