Axisymmetric periodic media such as annular layers have axi-symmetric
birefringence. I report the theoretical analysis of mode coupling in a
xisymmetric birefringent waveguides. Any of the LP11 modes in a pertur
bed system can couple with a corresponding LP11 mode that is orthogona
l to the original mode with respect to both the polarization direction
and the node line of an electric field. The coupling beat length depe
nds on the amount of birefringence, which can be as short as 5 mm for
a practical structure. (C) 1997 Optical Society of America.