High Power Masers based on 2D periodic structures: from the GHz to THz frequency range - Fisher, L; MacInnes, P; Konoplev, I; Cross, A; He, W; Ronald, K; Phelps, A; Whyte, C; Robertson, C; IEEE (2008 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES, VOLS 1 AND 2, 2008)