  We propose 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 Bi-2212 and related superconducting compounds. We show
that the JVs moving in a subset of 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.
