Patent ID: 8055110

Claim:
A single mode microstructured optical fiber comprising: a core region disposed about a longitudinal centerline and having a refractive index profile with a first refractive index, and a cladding region surrounding the core region, the cladding region comprising an annular hole-containing region comprised of non-periodically dispersed holes; wherein said non-periodically dispersed holes comprise a percent regional void area percent in said hole-containing region which is between 2 and 10 percent, and an average number density of holes in said hole-containing region is greater than 0.5 per microns 2 , and wherein said annular hole-containing region is doped with at least one dopant selected from fluorine having an average concentration of from 0.4 wt % to 1.2 wt % and chlorine having an average concentration of from 0.05 wt % to 0.2 wt %.