An optical fiber comprising: (i) a silica based passive core having a first index of refraction n.sub.1; (ii) a silica based cladding surrounding the core and having a second index of refraction n.sub.2, such that n.sub.1>n.sub.2, said cladding having at least one stress rod and at least one air hole extending longitudinally through the length of said optical fiber; and (iii) wherein said optical fiber supports a single polarization mode or poses polarization maintaining properties within the operating wavelength range.