An optical fiber having both low macrobend loss and low microbend loss.

The invention is directed to a single mode optical waveguide fiber profile (18, 20, 22, 24) that provides relatively large effective area while limiting macrobend loss.

The macrobend loss as measured by a 20 mm diameter bend test at 1550 nm is not more than 5.0 dB/m.

The system is particularly suited for measuring attenuation, including macrobend loss in which case a localized bending mechanism is employed, along the length of the fiber.

Macrobend loss, as measured by pin array or 20 mm mandrel testing, is maintained low by means of a power-limiting index depression (24) surrounding the central core region of the waveguide.