An optical fiber may comprise a core doped with one or more active ions to guide signal light from an input end of the optical fiber to an output end of the optical fiber, a cladding surrounding the core to guide pump light from the input end of the optical fiber to the output end of the optical fiber, and one or more inserts formed in the cladding surrounding the core. Each of the one or more inserts may have a geometry (e.g., a cross-sectional size, a helical pitch, and/or the like) that varies along a longitudinal length of the optical fiber, which may cause an absorption of the pump light to be modulated along the longitudinal length of the optical fiber.

An optical fiber includes (i) a chlorine doped silica based core having a core alpha (Core.sub.)4, a radius r.sub.1, and a maximum refractive index delta .sub.1max % and (ii) a cladding surrounding the core. The cladding surrounding the core includes a) a first inner cladding region adjacent to and in contact with the core and having a refractive index delta .sub.2, a radius r.sub.2, and a minimum refractive index delta .sub.2min such that .sub.2min<.sub.1max, b) a second inner cladding adjacent to and in contact with the first inner cladding having a refractive index .sub.3, a radius r.sub.3, and a minimum refractive index delta .sub.3min such that .sub.3min<.sub.2, and c) an outer cladding region surrounding the second inner cladding region and having a refractive index .sub.5, a radius r.sub.max, and a minimum refractive index delta .sub.3min such that .sub.3min<.sub.2. The optical fiber has a mode field diameter MFD at 1310 of 9 microns, a cable cutoff of 1260 nm, a zero dispersion wavelength of 1300 nmzero dispersion wavelength 1324 nm, and a macrobending loss at 1550 nm for a 20 mm mandrel of less than 0.75 dB/turn.

A rollable optical fiber ribbon utilizing low attenuation, bend insensitive fibers and cables incorporating such rollable ribbons are provided. The optical fibers are supported by a ribbon body, and the ribbon body is formed from a flexible material such that the optical fibers are reversibly movable from an unrolled position to a rolled position. The optical fibers have a large mode filed diameter, such as 9 microns at 1310 nm facilitating low attenuation splicing/connectorization. The optical fibers are also highly bend insensitive, such as having a macrobend loss of 0.5 dB/turn at 1550 nm for a mandrel diameter of 15 mm.

A low attenuation optical cable is provided. The cable includes an outer cable jacket and at least one buffer tube surrounded by the cable jacket. The cable includes a plural number of optical fibers located within the channel of the at least one buffer tube. The cable includes small sized active particles located within the buffer tube, and an average maximum outer dimension of the active particles within the buffer tube is 50 microns. The small sized active particles reduce microbending-based attenuation otherwise seen with larger sized active particles, particularly within densely packed buffer tubes.

An optical fiber includes (i) a chlorine doped silica based core having a core alpha (Core.sub.)4, a radius r.sub.1, and a maximum refractive index delta .sub.1 max% and (ii) a cladding surrounding the core. The cladding surrounding the core includes a) a first inner cladding region adjacent to and in contact with the core and having a refractive index delta .sub.2, a radius r.sub.2, and a minimum refractive index delta .sub.2 min such that .sub.2 min<.sub.1 max, b) a second inner cladding adjacent to and in contact with the first inner cladding having a refractive index .sub.3, a radius r.sub.3, and a minimum refractive index delta .sub.3 min such that .sub.3 min<.sub.2, and c) an outer cladding region surrounding the second inner cladding region and having a refractive index .sub.5, a radius r.sub.max, and a minimum refractive index delta .sub.3 min such that .sub.3 min<.sub.2. The optical fiber has a mode field diameter MFD at 1310 of 9 microns, a cable cutoff of 1260 nm, a zero dispersion wavelength of 1300 nmzero dispersion wavelength 1324 nm, and a macrobending loss at 1550 nm for a 20 mm mandrel of less than 0.75 dB/turn.

A high bandwidth radiation-resistant multimode optical fiber includes a core and a cladding layer surrounding the core. The core is a fluorine-doped quartz glass layer with a graded refractive index distribution and a distribution power exponent of 1.7-2.2. The core has R1 of 15-35 m and 1%min of 0.8% to 1.2%. The cladding layer has an inner cladding layer having R2 of 15-38 m and 2% of 0.8% to 1.2% and/or a depressed inner cladding layer having R3 of 15-55 m and 3 of 1.0% to 1.4%, an intermediate cladding layer having R4 of 15.5-58 m and 4 of 0.7% to 0.2% a depressed cladding layer hasving R5 of 16-60 m and 5 of 0.8% to 1.2%, and an outer cladding layer sequentially formed from inside to outside. The outer cladding layer is a pure silica glass layer.

A low attenuation optical cable is provided. The cable includes an outer cable jacket and at least one buffer tube surrounded by the cable jacket. The cable includes a plural number of optical fibers located within the channel of the at least one buffer tube. The cable includes small sized active particles located within the buffer tube, and an average maximum outer dimension of the active particles within the buffer tube is 50 microns. The small sized active particles reduce microbending-based attenuation otherwise seen with larger sized active particles, particularly within densely packed buffer tubes.

An optical fiber includes (i) a chlorine doped silica based core having a core alpha (Core.sub.)4, a radius r.sub.1, and a maximum refractive index delta .sub.1 max% and (ii) a cladding surrounding the core. The cladding surrounding the core includes a) a first inner cladding region adjacent to and in contact with the core and having a refractive index delta .sub.2, a radius r.sub.2, and a minimum refractive index delta .sub.2 min such that .sub.2 min<.sub.1 max, b) a second inner cladding adjacent to and in contact with the first inner cladding having a refractive index .sub.3, a radius r.sub.3, and a minimum refractive index delta .sub.3 min such that .sub.3 min<.sub.2, and c) an outer cladding region surrounding the second inner cladding region and having a refractive index .sub.5, a radius r.sub.max, and a minimum refractive index delta .sub.3 min such that .sub.3 min<.sub.2. The optical fiber has a mode field diameter MFD at 1310 of 9 microns, a cable cutoff of 1260 nm, a zero dispersion wavelength of 1300 nmzero dispersion wavelength1324 nm, and a macrobending loss at 1550 nm for a 20 mm mandrel of less than 0.75 dB/turn.

A rollable optical fiber ribbon utilizing low attenuation, bend insensitive fibers and cables incorporating such rollable ribbons are provided. The optical fibers are supported by a ribbon body, and the ribbon body is formed from a flexible material such that the optical fibers are reversibly movable from an unrolled position to a rolled position. The optical fibers have a large mode filed diameter, such as ?9 microns at 1310 nm facilitating low attenuation splicing/connectorization. The optical fibers are also highly bend insensitive, such as having a macrobend loss of ?0.5 dB/turn at 1550 nm for a mandrel diameter of 15 mm.

The present invention relates to a multi-core optical fiber having a plurality of cores (102) and a cladding (108) surrounding the plurality of cores (102). The cladding (108) has a peripheral cladding layer (108b) that is down doped such that a leakage loss of the multi-core optical fiber (100) is less than 0.001 Decibel/Kilometer (dB/Km) at a wavelength 1550 nanometers (nm).