Polarization properties of fused fiber couplers and polarizing beamsplitters

The polarization properties of fused taped fiber couplers were investigated experimentally by changing cross-sectional shapes at the coupler waist. The coupling difference between x and y polarized light was studied for many test fused fiber couplers with various cross-sectional shapes. On the basis of the experimental results, two polarizing beamsplitters with the aspect ratio of 1.1 and 1.8 were produced, and their chromatic characteristics were measured. It was evident that the aspect ratio should be more than 1.7 to manufacture polarizing beamsplitters with few power transfer cycles, i.e. long spectral period. Splitting ratios of polarizing beamsplitters with the aspect ratio of 1.1 and 1.8 were 17.6 and -12.7 dB for x polarized light and -16.1 and 11.7 dB for gamma polarized light, respectively. Their losses were less than 0.6 and 0.3 dB.>