Disclosed is a single mode optical waveguide fiber having a low cut off
wavelength, and mode field diameter and bend resistance similar to step index single
mode optical waveguide fiber designed for use at 1310 nm. By including a clad region
of raised refractive index spaced apart from the core region of the single mode
optical waveguide fiber, the cut off wavelength can be reduced to 850 nm. The single
mode optical waveguide fiber in accord with the invention may also have a core
region having a reduced refractive index on centerline surrounded by a region of
higher refractive index and a clad region which is substantially uniform. The single
mode optical waveguide fiber is thus ideally suited for use with the low cost,
reliable VCSEL operating at 850 nm, a Fabry-Perot laser operating at 1310 nm, or
a distributed feedback laser operating at 1550 nm thereby enabling low cost, easily
installed, home access portions of the broadband telecommunications system.