An optical fiber comprising: (i) a core region comprising an outer radius r.sub.1, and 3.0r.sub.17.0 microns and a relative refractive index .sub.1max and 0.32%.sub.1max0.5%; (b) a depressed index cladding region surrounding the core region comprising an outer radius r.sub.3 and a relative refractive index .sub.3 less than 0.2%, and trench volume V.sub.3 wherein 45% -micron.sup.2|V.sub.3|200% -micron.sup.2; (c) a first outer cladding region surrounding the depressed index cladding region and comprising a relative refractive index .sub.4 and an outer radius r.sub.4; and (d) a second outer cladding layer comprising 5 wt %-20 wt % titania, a relative refractive index .sub.5, and a thickness T.sub.M, wherein 3 micronT.sub.M30 microns, and outer radius r.sub.565 microns; the optical fiber has a mode field diameter MFD.sub.1550 and 8 micronsMFD.sub.155010.5 microns, a cutoff wavelength 1550 nm when bent 1 turn around a 2.5 mm radius mandrel, and a bending loss at 1550 nm when using a mandrel comprising a radius of 2.5 mm of 1.0 dB/turn.

An optical fiber comprising: (i) a core region comprising an outer radius r.sub.1, and 3.0r.sub.17.0 microns and a relative refractive index .sub.1max and 0.32%.sub.1max0.5%; (b) a depressed index cladding region surrounding the core region comprising an outer radius r.sub.3 and a relative refractive index .sub.3 less than 0.2%, and trench volume V.sub.3 wherein 45% -micron.sup.2|V.sub.3|200% -micron.sup.2; (c) a first outer cladding region surrounding the depressed index cladding region and comprising a relative refractive index .sub.4 and an outer radius r.sub.4; and (d) a second outer cladding layer comprising 5 wt %-20 wt % titania, a relative refractive index .sub.5, and a thickness T.sub.M, wherein 3 micronT.sub.M30 microns, and outer radius r.sub.565 microns; the optical fiber has a mode field diameter MFD.sub.1550 and 8 micronsMFD.sub.155010.5 microns, a cutoff wavelength <1550 nm when bent 1 turn around a 2.5 mm radius mandrel, and a bending loss at 1550 nm when using a mandrel comprising a radius of 2.5 mm of 10 dB/turn.

An optical fiber comprising: (i) a chlorine doped silica based core comprising a core alpha ()>10, and maximum refractive index delta .sub.1max % and Cl concentration >1 wt %; (ii) a cladding surrounding the core, the cladding comprising: (a) an inner cladding region adjacent to and in contact with the core and having a refractive index delta .sub.2 and a minimum refractive index delta .sub.2min such that .sub.2min<.sub.1max, the inner cladding region comprising fluorine doped silica and the refractive index delta .sub.2 with region that decreases with radial position, and (b) an outer cladding region surrounding the inner cladding region and having refractive index delta .sub.3, such that .sub.2min<.sub.3. The fiber has mode field diameter MFD at 1310 nm of 9 microns, a cable cutoff of 1260 nm, zero dispersion wavelength of 1300 nmzero dispersion wavelength 1324 nm and bend loss at 1550 nm for a 20 mm mandrel of less than 0.5 dB/turn.

An optical fiber comprising: (i) a core comprising silica and having a maximum relative refractive index delta .sub.1MAX; and LP01 effective area >100 m.sup.2 at 1550 nm; (ii) an inner cladding surrounding the core and having a minimum relative refractive index delta .sub.2MIN and .sub.coreMAX>.sub.2MIN; (iii) an outer cladding surrounding the inner cladding and comprising a first outer cladding portion with a maximum refractive index .sub.3A such that .sub.3A>.sub.2MIN; and another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta .sub.3B wherein with a maximum refractive index delta .sub.3B wherein .sub.3B>.sub.3A, said another portion being the outermost portion of the outer cladding; and (iv) a coating layer surrounding the outer cladding, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta .sub.C wherein .sub.C>.sub.3B.

An optical fiber cable has a sectional area of Ac [m.sup.2] and housing a number N of optical fibers. A transmission loss .sub.dB [dB/km], a mode field diameter W [m], an effective area Aeff [m.sup.2], an effective length L.sub.eff [km], and a wavelength dispersion D [ps/nm/km] of each of the optical fibers at a wavelength of 1550 nm satisfy a predetermined equation.

An optical fiber comprising: (i) a core comprising silica and having a maximum relative refractive index delta .sub.1MAX; and LP01 effective area>100 m.sup.2 at 1550 nm;

(ii) an inner cladding surrounding the core and having a minimum relative refractive index delta .sub.2MIN and .sub.coreMAX>.sub.2MIN; (iii) an outer cladding surrounding the inner cladding and comprising a first outer cladding portion with a maximum refractive index .sub.3A such that .sub.3A>.sub.2MIN; and another outer cladding portion surrounding the first outer cladding portion with a maximum refractive index delta .sub.3B wherein with a maximum refractive index delta .sub.3B wherein .sub.3B>.sub.3A, said another portion being the outermost portion of the outer cladding; and (iv) a coating layer surrounding the outer cladding, and in contact with said another outer cladding portion, the coating layer having a relative refractive index delta .sub.C wherein .sub.C>.sub.3B.

The present invention relates to an optical fiber with improved bend performance and manufacturing method thereof. The optical fiber (100) comprises a core region (108) defined by a core refractive index profile (200) and a cladding region (106) surrounding the core region defined by a cladding refractive index profile (400). Particularly, the core region has a first core (102) defined by a first core refractive index (RI) profile (202) and a first core RI max (peak) and a second core (104) defined by a second core RI profile (204) and a second core RI max (core). Moreover, the cladding region further comprises a first cladding (106) and a third cladding (110) composed of pure silica and a second cladding (108) composed of a down-doped silica, where the down-dopant is fluorine.