Low bend loss optical fiber

A single mode optical fiber comprising:

• (I) a core having outer radius r1, a maximum refractive index delta percent Δ1max and core alpha>5;
• (II) a cladding surrounding the core, the cladding comprising
• (i) inner cladding region having outer radius r2 and refractive index delta percent Δ2, wherein Δ1max>Δ2;
• and
• (ii) a trench region surrounding the inner cladding region, the trench region having an outer radius r3>10 microns and refractive index delta percent Δ3;
• and
• (iii) an outer cladding region having chlorine concentration larger than 1.2 wt. % surrounding the trench region and comprising refractive index delta percent Δ4;
• wherein Δ1max>Δ4 and Δ2>Δ3, and Δ4>Δ3 and wherein the Δ4−Δ3≧0.12 percent, and said fiber exhibits a mode field diameter MFD>9 microns at 1310 nm wavelength, cable cutoff of less than 1260 nm, and bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn, and 1300 nm≦λ0≦1324 nm, where λ0 is the zero dispersion wavelength.