This paper discusses the transmission and coupling losses of hollow dielectric waveguide modes in a folded waveguide structure. The folded structure consists of two square-bore waveguides placed symmetrically above a spherical mirror with a nonzero on-axis angle between them. The presence of the fold renders the structure astigmatic. However, for moderate fold angles (10–20°), the effect of the fold is negligible.
© 1989 Optical Society of America
J. Banerji, A. R. Davies, P. E. Jackson, and R. M. Jenkins, "Transmission and coupling losses in a folded waveguide," Appl. Opt. 28, 4637-4643 (1989)