Propagation of lower-order modes in a radially anisotropic cylindrical waveguide with liquid crystal cladding

The propagation behavior of the four lower-order modes, HE/sub 11/, TE/sub 01/, TM/sub 01/, and HE/sub 21/, in a radially anisotropic cylindrical waveguide with liquid crystal cladding is studied both theoretically and experimentally. The cylindrical waveguide is a doubly-clad fiber with an isotropic core and inner cladding and a radially anisotropic outer cladding made of nematic liquid crystal. Theoretically, the propagation and decay constants for the TE/sub 01/ and TM/sub 01/ modes are obtained by solving the wave equations exactly, while those for the HE/sub 11/ and HE/sub 21/ modes are derived using perturbation techniques under the weakly guiding approximation. It is predicted that in such a structure the guided TE/sub 01/ mode can be separated from the leaky HE/sub 11/, TM/sub 01/, and HE/sub 21/ modes. The theoretical results show good agreement with the experimental observations for a 3 cm long fiber cell with a 5 /spl mu/m inner cladding radius.>