Abstract

Dispersion-shifted (DS) single-mode fibers are designed to have low dispersion and low attenuation in the 1550-nm wavelength region. To achieve this, these fibers require complex index profiles and may, therefore, exhibit characteristics that are different from those observed in unshifted fibers with generally simple index profiles.¹ Although DS fibers are optimized for operation at 1550 nm, it is generally considered useful to have the 1300-nm wavelength region also available for transmission. We, therefore, studied the cutoff wavelength behavior of a DS fiber with triangular-index core and a higher-index ring surrounding the core.² The results of the study show that for the bend diameter of 28 cm, used for specifying the cutoff wavelength of unshifted fibers as recommended by CCITT,³ the cutoff region of the DS fiber investigated exhibits an interesting hump which may impact on the definition of the cutoff wavelength of this fiber.

© 1988 Optical Society of America