Mode field distributions in the first bandgap of all-solid photonic bandgap fibers

The mode field distributions at different wavelengths in the first bandgap of all-solid photonic bandgap fibers were numerically studied by multipole method. The corresponding 2D distributions of the normalized intensity were obtained by the same method. The mode field distributions in x and y directions were shown as the two directions were representative in the fiber with six-fold rotational symmetry. In the long-wavelength regime the mode field radii in the two directions are not equal and both decrease as the wavelength increases, which is different from the change in total internal reflection fibers.