Measured group birefringence B_g(λ) over 1250–1650 nm (black solid line, with square dots for the measurements), measured phase birefringence B at 1550 nm (red circular dot), and deduced phase birefringence B(λ) over 1250–1650 nm (red dashed line): (a) bow-tie fiber; (b) panda fiber; (c) tiger-eye fiber. Photographs of the end face of the fibers are inserted; SAPs are dark, while the circular cores are illuminated.