Methods of forming a bandwidth-tuned optical fiber for short-length data transmission systems include establishing a relationship between a change in a modal delay , a change T in a draw tension T and a change in a BM wavelength of light in a BM wavelength range from 840 nm and 1100 nm for a test optical fiber drawn from a preform and that supports BM operation at the BM wavelength. The methods also include drawing from either the preform or a closely related preform the bandwidth-tuned optical fiber by setting the draw tension based on the established relationships of the aforementioned parameters so that the bandwidth-tuned optical fiber has a target bandwidth greater than 2 GHz.Math.km at a target wavelength within the BM wavelength range.

A method of manufacturing a multimode optical fiber includes specifying a peak wavelength .sub.P for the multimode optical fiber. The peak wavelength .sub.P corresponds to a wavelength at which the multimode optical fiber has a maximum bandwidth. The multimode optical fiber comprises a core and a cladding surrounding and directly adjacent to the core. The core has a radius r.sub.1 and a maximum relative refractive index .sub.1,MAX>0. The cladding comprises a depressed-index region having a minimum relative refractive index .sub.3,MIN<0 and a volume v. A draw tension T for the multimode optical fiber is selected based on a correlation relating peak wavelength .sub.P to draw tension T, the correlation comprising a correlation constant. The correlation constant K is a function of at least one of .sub.1,MAX, r.sub.1, v, .sub.3,MIN, and .sub.P. The multimode optical fiber is drawn from a preform at the draw tension T.

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.

A method for a defined deposition of a glass layer on an inner wall of a preform for an optical fiber and/or for setting a refractive index profile of the preform for a multi-mode fiber. The method includes providing the preform having a cavity and an inner wall which defines an inner diameter of the preform, and spreading a deposition gas at a flow speed (v) in the cavity of the preform so as to provide the defined deposition of the glass layer. The defined deposition is performed at a reduced change in the flow speed a*v, where a<1. Based on the defined deposition, a change in the flow speed (v): $v=\frac{4Q}{}.Math.\left(\frac{1}{d_i^2}-\frac{1}{d_{i+1}^2}\right)$
forms at a volume flow (Q), a first diameter (d.sub.i), and a second diameter (d.sub.i+1).

A co-doped optical fiber is provided having an attenuation of less than about 0.17 dB/km at a wavelength of 1550 nm. The fiber includes a core in the fiber having a graded refractive index profile with an alpha of greater than 5. The fiber also includes a cladding in the fiber that surrounds the core addition, the core includes silica that is co-doped with two or more halogens.

A method of forming an optical fiber, including: exposing a soot core preform to a dopant gas at a pressure of from 1.5 atm to 40 atm, the soot core preform comprising silica, the dopant gas comprising a first halogen doping precursor and a second halogen doping precursor, the first halogen doping precursor doping the soot core preform with a first halogen dopant and the second halogen precursor doping the soot core preform with a second halogen dopant; and sintering the soot core preform to form a halogen-doped closed-pore body, the halogen-doped closed-pore body having a combined concentration of the first halogen dopant and the second halogen dopant of at least 2.0 wt %.

The present disclosure relates to an optical fiber with shaped photosensitivity profile, comprising a nanostructured core composed of at least two types of glass rods, wherein at least one type of glass rods is doped with germanium. The invention relates also to a method for preparing an optical fiber with a core allowing for obtaining photoinduced refractive index modulation. Depending on their specific type, such optical fibers are applicable i.a. in laser generation and in amplification techniques (active optical fibers) and/or in optical fiber sensors and telecommunications applications (passive optical fibers).

A method of manufacturing multi-mode optical fiber is disclosed. The method of manufacturing includes: a step of forming a first glass base material while controlling a supply rate of an additive for adjusting a refractive index to achieve a desired refractive index distribution; a step of drawing the first glass base material; a step of measuring a residual stress distribution in a radial direction of the multi-mode optical fiber after being drawn; a step of readjusting the supply rate of the additive in accordance with deviation of a refractive index, acquired from the residual stress distribution measured, from the desired refractive index distribution; a step of forming a second glass base material while supplying the additive at the supply rate after being readjusted; and a step of drawing the second glass base material.

The present embodiment relates to a production method for matching a shape of a refractive index profile of a core preform with an ideal curve with high precision and in a short time. Prior to a glass synthesis step of stacking a plurality of glass layers including a refractive index adjusting agent of a predetermined amount on an inner peripheral surface or on an outer peripheral surface of a glass deposition substrate, glass synthesis actual-result data is created from production condition data of a glass preform produced in the past and refractive index profile data of a core preform obtained from the glass preform. In each glass synthesis section where the glass synthesis step is executed, a doping amount of the refractive index adjusting agent is adjusted on the basis of the glass synthesis actual-result data.

A co-doped optical fiber is provided having an attenuation of less than about 0.17 dB/km at a wavelength of 1550 nm. The fiber includes a core in the fiber having a graded refractive index profile with an alpha of greater than 5. The fiber also includes a cladding in the fiber that surrounds the core addition, the core includes silica that is co-doped with two or more halogens.