A multicore optical fiber comprising: a depressed index common-cladding region having a refractive index Δ.sub.cc; and a plurality of core portions disposed within the depressed index common-cladding region, wherein each core portion comprises: a central axis, a core region comprising a relative refractive index Δ.sub.1, an inner-cladding region encircling and directly contacting the core region comprising a relative refractive index Δ.sub.2, a trench region encircling and directly contacting the inner cladding region comprising a relative refractive index Δ.sub.3, and an outer-cladding region encircling and directly contacting the trench region comprising a relative refractive index Δ.sub.4, wherein the refractive index of the depressed index common-cladding region Δ.sub.cc is less than the refractive index of the outer-cladding region Δ.sub.4, and wherein a difference between the refractive index of the depressed index common-cladding region Δ.sub.cc and the refractive index of the first outer-cladding region Δ.sub.4 is greater than 0.05% Δ.

An object of the present invention is to provide a multi-core optical fiber that can prevent an increase in bending loss even when a distance between a peripheral core and a cladding boundary is decreased, and can improve a bending loss characteristic in a state where an influence on a cutoff wavelength and a mode field diameter is small, and a design method thereof.

The multi-core optical fiber according to the present invention is an optical fiber in which two or more core regions are arranged in a cladding region having a refractive index lower than a refractive index of the core at a minimum core interval, a ring-shaped low refractive index region surrounding the core and having a refractive index lower than the refractive index of the cladding region is provided, a bending loss after the provision of the ring-shaped low refractive index region is reduced as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided, and at the same time, a change in mode field diameter after the provision of the ring-shaped low refractive index region is not changed as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided.

A fiber optic cable includes a cable jacket having an outer surface defined by a cable jacket outer diameter J.sub.OD and an inner surface defined by a cable jacket inner diameter J.sub.ID; a plurality N of optical fibers, where N≥4, contained within the cable jacket and positioned a distance away from the cable jacket inner diameter, with each optical fiber having a core, a cladding surrounding the core, and at least one coating surrounding the core with the at least one coating having an outer coating diameter less than or equal to about 200 microns and wherein the cable jacket outer diameter J.sub.OD is less than or equal to 1 mm.

A multicore optical fiber includes an inner glass region having a plurality of core regions surrounded by a common outer cladding, the inner glass region further having at least one marker and an outer diameter in the range of 120 microns and 130 microns, wherein each core region is comprised of a germania-doped silica core and a fluorine-doped silica trench, wherein the trench volume of the fluorine-doped silica trench is greater than 50% Δ microns.sup.2. The fiber has an outer coating layer surrounding the inner glass region, the outer coating layer having a primary coating layer and a secondary coating layer with a diameter of the secondary coating layer equal to or less than 200 microns, wherein each core region has a mode field diameter greater than 8.2 microns at 1310 nm, a cable cutoff wavelength of less than 1260 nm, and zero dispersion wavelength of less than 1335 nm.

A fiber optic cable includes an optical fiber, a strength layer surrounding the optical fiber, and an outer jacket surrounding the strength layer. The strength layer includes a matrix material in which is integrated a plurality of reinforcing fibers. A fiber optic cable includes an optical fiber, a strength layer, a first electrical conductor affixed to an outer surface of the strength layer, a second electrical conductor affixed to the outer surface of the strength layer, and an outer jacket. The strength layer includes a polymeric material in which is embedded a plurality of reinforcing fibers. A method of manufacturing a fiber optic cable includes mixing a base material in an extruder. A strength layer is formed about an optical fiber. The strength layer includes a polymeric film with embedded reinforcing fibers disposed in the film. The base material is extruded through an extrusion die to form an outer jacket.

An optical fiber includes: a core portion made of glass; and a cladding portion made of glass, having a refractive index lower than the refractive index of the core portion, and positioned on an outer periphery of the core portion. Further, the cladding portion has an outer diameter smaller than 100 μm, and the core portion has a relative refractive-index difference of 0.32% to 0.40% with respect to the cladding portion.

An optical fiber preform including a glass material and a refractive index adjusting additive is disclosed. This preform has striae due to difference in concentration of the additive and the striae have concentric refractive index periodicity in at least a part thereof from a radial center of the preform to an outer periphery thereof. The respective striae pitches each indicating a period of the refractive index periodicity increase from the center of the preform to the outer periphery thereof.

An optical fiber includes a core with radius r1, a first clad layer with outermost radius r2 adjacent to the core at radial position r1 and covering the outer periphery of the core, a second clad layer with outermost radius r3 adjacent to the first clad layer at radial position r2 and covering the outer periphery of the first clad layer, and a third clad layer adjacent to the second clad layer at radial position r3 and covering the outer periphery of the second clad layer. The refractive index of the first clad layer decreases continuously from the inside to the outside, reaching a maximum value at radial position r1 and a minimum value at radial position r2. The refractive index of the second clad layer increases continuously from the inside to the outside, reaching a minimum value at radial position r2 and a maximum value at radial position r3.

The disclosure provides optical fibers that exhibit low macrobend loss at 1550 nm at bend diameters between 10 mm and 40 mm. The relative refractive index profile of the fibers includes a trench cladding region with small depth, large width and a trench volume configured to minimize macrobend loss at large and small bend diameters. The optical fiber includes an outer cladding region that surrounds and is directly adjacent to the trench cladding region and an optional offset cladding region between the trench cladding region and the core region. In some embodiments, the trench cladding region has a relative refractive index that decreases monotonically from the inner radius to the outer radius. The monotonic decrease in relative refractive index may have a constant slope. The low macrobend loss at large and small diameters makes the optical fibers well suited for space-constrained deployment environments, such as data centers.

Optical fibers having a large effective area and a low cutoff wavelength are disclosed. Three main embodiments of the optical fiber allow for single-mode operation at wavelengths greater than 980 nm, and have a large effective area with low bend losses and low dispersion at 1310 nm. The large effective area optical fiber is expected to be particularly useful for data center applications due to its ability to efficiently optically couple with VCSELs and photonic integrated devices. Integrated systems and optical communication systems that employ the optical fibers are also disclosed.