Volume and surface mode coupling experiments in periodic surface structures for use in mm-THz high power radiation sources

MacLachlan, A.J. and Robertson, C.W. and Cross, A.W. and Phelps, A.D.R. (2018) Volume and surface mode coupling experiments in periodic surface structures for use in mm-THz high power radiation sources. AIP Advances, 8 (10). 105115. ISSN 2158-3226 (https://doi.org/10.1063/1.5020542)

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Abstract

Planar Periodic Surface Lattice (PSL) structures of different configurations have been designed, fabricated and measured in the 140-220 GHz frequency band. Surface mode resonances are observed in ‘mesh’ PSL structures. We establish that, when mounted on suitable metal-backed dielectric substrates, PSLs exhibit ‘modelocked’ coherent cavity eigenmodes formed from coupled volume and surface modes. The ‘proof-of-principle’ coupling of volume and surface modes and concept of mode selection in a large cavity, which can lead to the innovation of high power mm-THz radiation sources, is demonstrated. Evidence of coupled eigenmode formation in a 0.64 mm planar PSL measured at 325-500 GHz is presented, verifying the scalability of this work. Excellent agreement between numerical modelling and experiment is reported.