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.

There is described a multi-clad optical fiber for propagating an optical signal having at least a single mode. The multi-clad optical fiber generally has a fiber core, an inner cladding surrounding the fiber core, and at least an outer cladding surrounding the inner cladding, the multi-clad optical fiber having at least a taper portion extending along a longitudinal dimension z, the taper portion having a radial dimension progressively decreasing at a normalized slope exceeding an adiabaticity criterion of a conventional single-clad optical fiber propagating at least the single-mode across its single-mode core.

A substrate can include an optical light guide including a core. The core can include a fluorescent material in a content of greater than 0.5 wt. % for the total weight of the core. In an embodiment, the optical light guide can include a scintillator material. In another embodiment the core can include polyethylene naphthalate (PEN) and a polyvinylidene difluoride cladding.

A method of processing by controlling one or more beam characteristics of an optical beam may include: launching the optical beam into a first length of fiber having a first refractive-index profile (RIP); coupling the optical beam from the first length of fiber into a second length of fiber having a second RIP and one or more confinement regions; modifying the one or more beam characteristics of the optical beam in the first length of fiber, in the second length of fiber, or in the first and second lengths of fiber; confining the modified one or more beam characteristics of the optical beam within the one or more confinement regions of the second length of fiber; and/or generating an output beam, having the modified one or more beam characteristics of the optical beam, from the second length of fiber. The first RIP may differ from the second RIP.

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.

An optical fiber amplifier comprising first, second and third optical fibers, and first, second and third lenses, is disclosed. First cores of the first optical fiber and second cores of the second optical fiber have homothetic arrangement each other in the arrangement of outer cores. The first core has a mode field diameter MFD1S when transmitting an optical signal and a core pitch P1, and the first lens has a focal distance f1S at the wavelength of the optical signal. The second core has a mode field diameter MFD2S when transmitting the optical signal and a core pitch P2, and the second lens has a focal distance f2S at the wavelength. The MFD1S of each first core is within ±25% of MFD2S×(P1/P2) of the corresponding second core, and the MFD1S of each first core is within ±25% of MFD2S×(f1S/f2S) of the corresponding second core.

In various embodiments, the beam parameter product and/or beam shape of a laser beam is adjusted by coupling the laser beam into an optical fiber of a fiber bundle and directing the laser beam onto one or more in-coupling locations on the input end of the optical fiber. The beam emitted at the output end of the optical fiber may be utilized to process a workpiece.

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 according to an embodiment includes a core and a cladding. The average value n1_ave of the refractive index of the core, the minimum value nc_min of the refractive index of the cladding, and the refractive index n0 of pure silica glass satisfy relationships of n1_ave>nc_min and nc_min<n0. The cladding contains fluorine. The fluorine concentration in the cladding is adjusted to be minimum in the outermost portion of the cladding including the outer peripheral surface of the cladding.

An optical fiber includes a core that propagates a light that includes a wavelength of 1060 nm. The light propagates in the core at least in an LP01 mode and an LP11 mode. A difference between a propagation constant of the light in the LP01 mode and a propagation constant of the light in the LP11 mode is 2000 rad/m or smaller. The expression

[00001]$L\frac{.Math.M^2}{-2.Math.3.Math.7.Math.21.Math.0^{-6}.Math.+4.8.Math.1.Math.91.Math.0^{-3}}$

is satisfied, where L is a length, M.sup.2 is a beam quality of light, M.sup.2 is a deterioration amount of the beam quality of light due to propagation in the optical fiber.