Patent ID: 8666214

Claim:
A single mode optical fiber comprising: a graded index central core region having outer radius r 1 , having a relative refractive index Δ 1 , a maximum relative refractive index Δ 1max and having an alpha profile, alpha core , of 0.5≦alpha core ≦4; a cladding region including (a) a trench region surrounding said graded index central core region and comprising a relative refractive index delta Δ 3 profile that becomes more negative with increasing radius, said trench region having an inner radius r 2 , an outer radius r 3 >10 microns, and a minimum relative refractive index Δ 3min such that Δ 1max >Δ 3min , r 3 ≧r 3a , and 0.5≦(r 3a −r 2 )/(r 3 −r 2 )≦1, where r 3a is a distance from fiber centerline where Δ 3 first reaches the value Δ 3min , said trench region having an alpha profile, alpha t such that 0.5≦alpha t ≦5, and (b) an outer cladding region surrounding said trench region and having a relative refractive index Δ 4 , and Δ 3min <Δ 4 , and wherein 0.08%≦|Δ 4 −Δ 3min |≦0.7% and the absolute difference between Δ 3min and Δ 2 is greater than 0.03, the absolute value V 3a3 of the trench region is 5% Δmicrons 2 ≦V 3a3 ≦105% Δmicrons 2 , and said fiber exhibits a 22 m cable cutoff less than or equal to 1400 nm.