Geometry, Sagnac ring lasers and twisted EM modes

Tucker, Robin W. and Burton, David A. and Noble, Adam (2005) Geometry, Sagnac ring lasers and twisted EM modes. General Relativity and Gravitation, 37 (9). pp. 1555-1574. ISSN 0001-7701

Abstract

A new geometric approximation scheme, designed to solve the covariant Maxwell equations inside a rotating hollow slender conducting cavity (modelling a ring-laser) on a background spacetime, is constructed. It is shown that for well-defined conditions the electromagnetic spectrum splits into TE- and TM-type modes. A twisted mode spectrum is found to depend on the integrated Frenet torsion of the cavity and this in turn may affect the Sagnac beat frequency induced by a non-zero rotation of the cavity.