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Optimal cladding structure of holey fiber designed for broadband fiber-optic wave plate

Two asymmetric structures are combined together in holey cladding of microstructure fiber. One is the rectangular lattice of holes elongated in y-axis. The other is a pair of holes with enlarged diameters near the fiber core oppositely along xaxis. The influence of structural parameters on relation between birefringence with wavelength is calculated. Their interaction at different wavelength can make the beat length insensitive to wavelength. By optimizing the lattice pitches and the holes diameter, 10mm stable beat length with relative bandwidth 12% are obtained in 1310nm and 1550nm bands. This holey fiber is suitable for fabricating wideband fiber-optic wave-plate.