Cavity mode waves during terahertz radiation from rectangular Bi(2)Sr(2)CaCu(2)O(8 + δ) mesas.

We re-examined the angular dependence of the radiation from the intrinsic Josephson junctions in rectangular mesas of Bi(2)Sr(2)CaCu(2)O(8 + δ), in order to determine if the cavity mode part of the radiation arises from waves across the width w or along the length l of the mesas, associated with 'hot spots' (Wang et al 2010 Phys. Rev. Lett.