Patent ID: 8526773

Claim:
An optical fiber comprising: (i) a core having a first index of refraction n 1 ; (ii) a cladding having cladding material surrounding the core having a second index of refraction n 2 , such that n 1 >n 2 , said cladding surrounding at least two sets of glass stress rods extending longitudinally through the length of said optical fiber, the stress rods in one set of said at least two sets of glass stress rods having different softening points from softening points of the other set of stress rods; and (iii) wherein said optical fiber supports a single polarization mode or poses polarization maintaining properties within its operating wavelength range, wherein the core having a relative refractive index Δ 1 (relative to cladding) such that 0.1%≦Δ 1 ≦2%, and comprising GeO 2 6 to 40 wt %; the cladding material is silica based glass doped with Boron; and at least two of the stress rods are pure silica rods the cladding material having a softening point that is different from the softening point of either one of said stress rods.