Patent ID: 7526177

Claim:
A single mode optical transmission fiber, comprising: a depressed core having at least 0.41 weight percent fluorine, said depressed core possessing an absolute refractive index difference (|Δn 1 |) with pure silica of greater than 1.5×10 −3 ; and a depressed cladding having at least 1.2 weight percent fluorine, said depressed cladding possessing an absolute refractive index difference (|Δn 2 |) with pure silica of greater than 4.5×10 −3 ; wherein said fiber possesses an absolute refractive index difference (|Δn 2 |−|Δn 1 |) between its depressed cladding and its depressed core of at least about 3×10 −3 ; and wherein said fiber, at a wavelength of 1310 nanometers, exhibits a variation in attenuation of less than 100 percent for radiation between about 200 and 30,000 Gy at a rate of more than 1 Gy/s.