The bending losses of infrared metallic waveguides are studied by a mode-coupling analysis. Previous results obtained for slab waveguides are confirmed. The high losses observed in practice with circular guides are explained by the near degeneracy between the TE01 and TM11 modes. The method is also used to study losses due to nonsteady-state propagation, such as caused by input mismatch or varying bend radii. Circular metallic waveguides with a thin dielectric lining on the inside could perform better than unlined guides, from the points of view of uniform bending losses and single-mode propagation under arbitrary bends.
© 1981 Optical Society of America
Michel E. Marhic, "Mode-coupling analysis of bending losses in IR metallic waveguides," Appl. Opt. 20, 3436-3441 (1981)