The present disclosure provides optical fibers with an impact-resistant coating system. The fibers feature low microbending and high mechanical reliability. The coating system includes a primary coating and a secondary coating. The primary coating and secondary coating have reduced thickness to provide reduced radius fibers without sacrificing protection. The primary coating has a low spring constant and sufficient thickness to resist transmission of force to the glass fiber. The secondary coating has high puncture resistance. The outer diameter of the optical fiber is less than or equal to 200 μm.

An optical fiber includes: a core portion made of glass; a cladding portion that is located on an outer periphery of the core portion and that is made of glass having a lower refractive index than a refractive index of the core portion; and a coating portion that covers an outer periphery of the cladding portion. Further, an average value of a relative refractive-index difference of a center core of the core portion is 0.1 to 0.5%, a fiber diameter including the coating portion is equal to or smaller than 220 μm, an effective cutoff wavelength is longer than 1260 nm and smaller than 1530 nm, and a mode field diameter of light at 1550 nm is equal to or larger than 9 μm.

The optical fibers disclosed is a single mode optical fiber having a core region and a cladding region surrounding and directly adjacent to the core region. The core region can have a radius r.sub.1 in a range from 3.0 microns to 6.0 microns and a core volume V.sub.1 less than 6.0%-micron.sup.2. The cladding region can include a first outer cladding region and a second outer cladding region surrounding and directly adjacent to the first outer cladding region. The first outer cladding region can have a radius r.sub.4a, the second outer cladding region can have a radius r.sub.4b less than or equal to 65 microns and comprising silica based glass doped with titania. The disclosed single mode optical fiber can have a fiber cutoff wavelength λ.sub.CF less than 1530 nm.

An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor F.sub.μBL_GO is 2.6 ([GPa.sup.−1.Math.μm.sup.−10.5.Math.dB/turn].Math.10.sup.−27) or less, when represented by

F.sub.μBL_GO=F.sub.μBL_G×F.sub.μBL_O

by using geometry microbend loss characteristic F.sub.μBL_G and optical microbend loss characteristic F.sub.μBL_O.

A single mode optical fiber is provided that includes a core region having an outer radius ri and a maximum relative refractive index Δ.sub.1max. The single mode optical fiber further includes a cladding region surrounding the core region, the cladding region includes a depressed-index cladding region, a relative refractive index Δ.sub.3 of the depressed-index cladding region increasing with increased radial position. The single mode optical fiber has a bend loss at 1550 nm for a 15 mm diameter mandrel of less than about 0.75 dB/turn, a bend loss at 1550 nm for a 20 mm diameter mandrel of less than about 0.2 dB/turn, and a bend loss at 1550 nm for a 30 mm diameter mandrel of less than 0.005 dB/turn. Additionally, the single mode optical fiber has a mode field diameter of 9.0 microns or greater at 1310 nm wavelength.

An optical fiber is provided that includes a core region, a cladding region having a radius less than about 62.5 microns; a polymer coating comprising a high-modulus layer and a low-modulus layer, wherein a thickness of the low-modulus inner coating layer is in a range of 4 microns to 20 microns, the modulus of the low-modulus inner coating layer is less than or equal to about 0.35 MPa, a thickness of the high-modulus coating layer is in a range of 4 microns to 20 microns, the modulus of the high-modulus inner coating layer is greater than or equal to about 1.6 GPa, and wherein a puncture resistance of the optical fiber is greater than 20 g, and wherein a microbend attenuation penalty of the optical fiber is less than 0.03 dB/km, and wherein an outer diameter of the coated optical fiber is less than or equal to 175 microns.

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 (Δpeak) and a second core (104) defined by a second core RI profile (204) and a second core RI max (Δcore). 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.

The optical fibers disclosed is a single mode optical fiber having a core region and a cladding region surrounding and directly adjacent to the core region. The core region can have a radius r.sub.1 in a range from 3.0 microns to 6.0 microns and a core volume V.sub.1 less than 6.0%-micron.sup.2. The cladding region can include a first outer cladding region and a second outer cladding region surrounding and directly adjacent to the first outer cladding region. The first outer cladding region can have a radius r.sub.4a, the second outer cladding region can have a radius r.sub.4b less than or equal to 65 microns and comprising silica based glass doped with titania. The disclosed single mode optical fiber can have a fiber cutoff wavelength λ.sub.CF less than 1530 nm.

A low-dispersion single-mode fiber includes a core and claddings covering the core. The core layer has a radius in a range of 3-5 μm and a relative refractive index difference in a range of 0.15% to 0.45%. The claddings comprise a first depressed cladding, a raised cladding, a second depressed cladding, and an outer cladding arranged sequentially from inside to outside. The first depressed cladding has a unilateral width in a range of 2-7 μm and a relative refractive index difference in a range of −0.4% to 0.03%. The raised cladding has a unilateral width in a range of 2-7 μm and a relative refractive index difference in a range of 0.05% to 0.20%. The second depressed cladding has a unilateral width in a range of 0-8 μm and a relative refractive index difference in a range of 0% to −0.2%. The outer cladding is formed of pure silicon dioxide glass.

A fiber-optic system for use in optical sensing includes a multicore sensing fiber having at least two cores of which each of the at least two cores has a first core diameter, and a multicore lead-in fiber having at least two cores including a position corresponding with the position of the at least two cores of the multicore sensing fiber. Each of the at least two cores of the multicore lead-in fiber have a second core diameter. The second core diameter is substantially larger than the first core diameter. The system further includes an alignment means for aligning the multicore sensing fiber and the multicore lead-in fiber so that the lead-in fiber and the multicore sensing fiber are configured for coupling radiation between the fibers through the cores.