Optical fiber with large mode field diameter and low microbending losses

An optical waveguide fiber comprising:

• a central core region having a radius r1 and a relative refractive index Δ1(r) in % measured relative to pure silica, said relative refractive index Δ1(r) having a maximum Δ1max;
• a cladding, said cladding including an inner cladding region surrounding said central core region and an outer cladding region surrounding said inner cladding region, said inner cladding region having an outer radius r2>8 μm and a relative refractive index Δ2(r) in % measured relative to pure silica, said relative refractive index Δ2(r) having a maximum Δ2max and a minimum Δ2min, said outer cladding region having a relative refractive index Δ4 in % measured relative to pure silica, said relative refractive index Δ4 being positive and less than said maximum Δ1max, said relative refractive index Δ4 exceeding said minimum Δ2min by at least 0.002%;
• a primary coating surrounding said outer cladding region, said primary coating having an in situ modulus of less than 0.20 MPa and an in situ glass transition temperature of less than −35° C.;
• and
• a secondary coating surrounding said primary coating, said secondary coating having an in situ modulus of greater than 1500 MPa;
• wherein said fiber exhibits a 2 m cutoff wavelength less than 1360 nm.

An optical waveguide fiber comprising:

• a central core region having a radius r1 and a relative refractive index Δ1(r) in % measured relative to pure silica, said relative refractive index Δ1(r) having a maximum Δ1max;
• a cladding, said cladding including an inner cladding region surrounding said central core region and an outer cladding region surrounding said inner cladding region, said inner cladding region having an outer radius r2>8 μm and a relative refractive index Δ2(r) in % measured relative to pure silica, said relative refractive index Δ2(r) having a maximum Δ2max and a minimum Δ2min, said outer cladding region having a relative refractive index Δ4 in % measured relative to pure silica, said relative refractive index Δ4 being positive and less than said maximum Δ1max, said relative refractive index Δ4 exceeding said minimum Δ2min by at least 0.002%;
• a primary coating surrounding said outer cladding region, said primary coating having an in situ modulus of less than 0.20 MPa and an in situ glass transition temperature of less than −35° C.;
• and
• a secondary coating surrounding said primary coating, said secondary coating having an in situ modulus of greater than 1500 MPa;
• wherein said mode field diameter is greater than 9.0 μm at a wavelength of 1310 nm, said 2 m cutoff wavelength is less than 1320 nm, and said wire mesh covered drum microbending loss is less than 0.020 dB/km at a wavelength of 1550 nm when wound around a mesh-covered aluminum drum with a diameter of 400 mm.