The present disclosure provides an optical fibre. The optical fibre includes a core extended from a central longitudinal axis to a first radius r1. Further, the optical fibre includes a first trench region extended from a second radius r2 to a third radius r3, a second trench region extended from the third radius r3 to a fourth radius r4 and a cladding region extended from the fourth radius r4 to a fifth radius r5.

The present disclosure provides an optical fibre. The optical fibre includes a core region, a primary trench region and a secondary trench region. The core region has a radius r.sub.1. In addition, the core region has a relative refractive index Δ.sub.1. Further, the primary trench region has a relative refractive index Δ.sub.3. Furthermore, the primary trench region has a curve parameter α.sub.trench-1. Moreover, the secondary trench region has a relative refractive index Δ.sub.4. Also, the secondary trench region has a curve parameter α.sub.trench-2.

A optical fiber comprising a central core region having an outer radius r.sub.1 of 3 μm to 7 μm, and a maximum refractive index Δ.sub.1 of 0.25% to 0.5% and an alpha (a) profile of 1 to 20; a cladding region comprising (i) a first inner cladding region surrounding the core, having a refractive index Δ.sub.2 of −0.25% to 0.05% and a radius r.sub.2 of 6 μm to 15 μm, (ii) a second inner cladding region, surrounding the first inner cladding region, having a refractive index Δ.sub.3 of −0.1% to 0.2% and a radius r.sub.3 of 7 μm to 15 μm, and (iii) an outer cladding region, surrounding the second inner cladding region, having a refractive index Δ.sub.4 between −0.05% to 0.1%; wherein the optical fiber exhibits a cable cutoff of less than 1260 nm, a mode field diameter at 1310 nm of greater than 8.2 microns.

The optical fiber according to the present invention includes, in a cross section of the optical fiber, one core region (11) and a cladding region (12) that is arranged on an outer periphery of the core region. The cladding region is a medium that has a lower refractive index than that of the core region and also has a smaller refractive index wavelength dispersion than that of the core region. The optical fiber has a solid core and therefore, allows more reduction in the Rayleigh scattering loss compared to an optical fiber having a hollow core. In addition, since the optical fiber adopts, for the cladding region, a medium that has a smaller refractive index wavelength dispersion than that of the core region, it allows a reduction in the wavelength dispersion of n.sub.eff.

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.

An optical fiber includes (i) a chlorine doped silica based core having a core alpha (Core.sub.α)≥4, a radius r.sub.1, and a maximum refractive index delta Δ.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 Δ.sub.2, a radius r.sub.2, and a minimum refractive index delta Δ.sub.2min such that Δ.sub.2min<Δ.sub.1max, b) a second inner cladding adjacent to and in contact with the first inner cladding having a refractive index Δ.sub.3, a radius r.sub.3, and a minimum refractive index delta Δ.sub.3min such that Δ.sub.3min<Δ.sub.2, and c) an outer cladding region surrounding the second inner cladding region and having a refractive index Δ.sub.5, a radius r.sub.max, and a minimum refractive index delta Δ.sub.3min such that Δ.sub.3min<Δ.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 nm≤zero dispersion wavelength≤1324 nm, and a macrobending loss at 1550 nm for a 20 mm mandrel of less than 0.75 dB/turn.

In some embodiments, a data center optical communications system includes: a transmitter comprising a light source, wherein the light source is configured to provide light; an optical fiber operably connected to said transmitter and configured to receive light from the light source, wherein the optical fiber has a length L of 50 km or greater; a receiver configured to receive light from the optical fiber, wherein the receiver includes a detector for detecting the light, wherein the system has a power consumption of 15 W or less

The optical fiber offered is capable of not only restraining the attenuation due to glass defects, but also reducing the increase of manufacturing cost. The optical fiber is made of silica glass and includes a core and a cladding. The cladding encloses the core and has a refractive index smaller than that of the core. When the core is divided into inner core and outer core at half of the radius of the core, the average chlorine concentration of the inner core is larger than that of the outer core. The core includes any of the alkali metal group.

An optical fiber includes: a core; a depressed layer surrounding the core; and a cladding surrounding the depressed layer. A refractive index profile of the core is an α-th power distribution having an index α of 1.0 or more and 2.9 or less. A relative refractive index difference Δ.sup.− of the depressed layer with respect to the cladding has an absolute value |Δ.sup.−| that is 0.05% or more and 0.15% or less. A ratio r1/r2 of a radius r1 of the core to an outer radius r2 of the depressed layer is 0.35 or more and 0.60 or less. A cable cutoff wavelength λcc of 22 m is less than 1.26 μm. A mode field diameter at a wavelength of 1.31 inn is larger than 8.6 inn and smaller than 9.5 μm.

A present embodiment relates to a MDL measurement method and the like including a structure for enabling MDL measurement without increasing a processing load. The present embodiment sequentially executes, for N (≥2) spatial modes, light-input operation of inputting light of a predetermined intensity to an arbitrary spatial mode, and intensity measurement operation of measuring an output light intensity of each of the N spatial modes including the arbitrary spatial mode, to generate a transfer matrix relating to transmission loss in an optical fiber as a measurement target, and determine at least a linear value of MDL per unit fiber length by using each component value of the generated transfer matrix.