Patent ID: 8175437

Claim:
A single mode microstructured optical fiber for transmitting optical signals comprised of light, the optical fiber comprising: a void free 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 void-containing region comprised of non-periodically disposed voids which comprises a width between 2 and 10 microns, said void-containing region is spaced from the core at least 1 micron by an inner annular void free region, said cladding further comprising an outer void free region which surrounds said void-containing region; wherein said non-periodically disposed voids comprise a regional void area percent in said void-containing region which is between 2 and 10 percent, and an average number density of voids in said void-containing region is greater than 1 per microns 2 , and said fiber exhibits a 22 meter cutoff wavelength less than 1500 nm.