Optical waveguide cores having refractive index profiles that vary angularly about a propagation axis of the core can provide single-mode operation with larger core diameters than conventional waveguides. In one representative embodiment, an optical waveguide comprises a core that extends along a propagation axis and has a refractive index profile that varies angularly about the propagation axis. The optical waveguide can also comprise a cladding disposed about the core and extending along the propagation axis. The refractive index profile of the core can vary angularly along a length of the propagation axis.

A dispersion shifted optical fiber where a radius r.sub.0 of a first center segment is 0.5 μm to 2.8 μm, and a relative refractive index difference Δ.sub.0 is 0.4% or more and 0.9% or less. A radius r.sub.1 of a first segment is 1.8 μm or more and 4.5 μm or less. A radius r.sub.2 of a second segment is 4.0 μm or more and 8.0 μm or less, and a relative refractive index difference Δ.sub.2 is 0.00% or more and 0.07% or less. A radius r.sub.3 of a third segment is 4.5 μm or more and 8.5 μm or less, and a relative refractive index difference Δ.sub.3 is 0.285% or more and 0.5% or less. A radius r.sub.4 of a fourth segment is 8.0 μm or more and 16.0 μm or less, and a relative refractive index difference Δ.sub.4 is 0.005% or more and 0.04% or less.

A test apparatus has at least one optical source, a high-speed photodetector, a microcontroller or processor, and electrical circuitry to power and drive the optical source, high-speed photodetector, and microcontroller or processor. The apparatus measures the frequency response and optical path length of a multimode optical fiber under test, utilizes a reference VCSEL spatial spectral launch condition and modal-chromatic dispersion interaction data to estimate the channels total modal-chromatic bandwidth of the fiber under test, and computes and presents the estimated maximum data rate the fiber under test can support.

The present disclosure provides a universal optical fiber (100). The universal optical fiber (100) includes a core (102) extended from a central longitudinal axis (110) to a first radius r.sub.1. In addition, the universal optical fiber (100) includes a buffer clad (104) region extending from the first radius r.sub.1 to a second radius r.sub.2. Further, the universal optical fiber (100) includes a trench region (106) extending from the second radius r.sub.2 to a third radius r.sub.3. Furthermore, the universal optical fiber (100) includes a cladding (108) extending from the third radius to a fourth radius r.sub.4. Moreover, the core (102), the buffer clad region (104), the trench region (106) and the cladding (108) are concentrically arranged.

The present disclosure provides a universal optical fiber (100). The universal optical fiber (100) includes a core (102) extended from a central longitudinal axis (110) to a first radius r.sub.1. In addition, the universal optical fiber (100) includes a buffer clad (104) region extending from the first radius r.sub.1 to a second radius r.sub.2. Further, the universal optical fiber (100) includes a trench region (106) extending from the second radius r.sub.2 to a third radius r.sub.3. Furthermore, the universal optical fiber (100) includes a cladding (108) extending from the third radius to a fourth radius r.sub.4. Moreover, the core (102), the buffer clad region (104), the trench region (106) and the cladding (108) are concentrically arranged.

An optical fiber includes: a central core portion; an intermediate layer; a trench layer; and a cladding portion. Further, relationships Δ1>Δ2>Δ3 and 0>Δ3 are satisfied, where Δ1, Δ2, and Δ3 are a relative refractive-index difference of the central core portion, the intermediate layer, and the trench layer, respectively, with respect to the cladding portion, Δ1 is equal to or larger than 0.34% and equal to or smaller than 0.37%, |Δ3| is equal to or larger than 0.1% and equal to or smaller than 0.25%, Δ1×|Δ3| is equal to or smaller than 0.08%.sup.2, a mode field diameter at a wavelength of 1310 nm is equal to or larger than 8.8 μm, and a transmission loss at a wavelength of 1550 nm is equal to or smaller than 0.195 dB/km.

An optical fiber includes: a central core portion; an intermediate layer; a trench layer; and a cladding portion. Further, relationships Δ1>Δ2>Δ3 and 0>Δ3 are satisfied, where Δ1, Δ2, and Δ3 are a relative refractive-index difference of the central core portion, the intermediate layer, and the trench layer, respectively, with respect to the cladding portion, Δ1 is equal to or larger than 0.34% and equal to or smaller than 0.37%, |Δ3| is equal to or larger than 0.1% and equal to or smaller than 0.25%, Δ1×|Δ3| is equal to or smaller than 0.08%.sup.2, a mode field diameter at a wavelength of 1310 nm is equal to or larger than 8.8 μm, and a transmission loss at a wavelength of 1550 nm is equal to or smaller than 0.195 dB/km.

Methods for modifying multi-mode optical fiber manufacturing processes are disclosed. In one embodiment, a method for modifying a process for manufacturing multi-mode optical fiber includes measuring at least one characteristic of a multi-mode optical fiber. The at least one characteristic is a modal bandwidth or a differential mode delay at one or more wavelengths. The method further includes determining a measured peak wavelength of the multi-mode optical fiber based on the measured characteristic, determining a difference between the target peak wavelength and the measured peak wavelength, and modifying the process for manufacturing multi-mode optical fiber based on the difference between the target peak wavelength and the measured peak wavelength.

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 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.