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.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

A single mode optical fiber is provided that includes a core region having an outer radius r.sub.1 and a maximum relative refractive index Δ1.sub.max. The single mode optical fiber has a bend loss at 1550 nm for a 15 mm diameter mandrel of less than about 0.75 dB/turn, has a bend loss at 1550 nm for a 20 mm diameter mandrel of less than about 0.2 dB/turn, and a bend loss at 1550 nm for a 30 mm diameter mandrel of less than 0.002 dB/turn. Additionally, the single mode optical fiber has a mode field diameter of 9.0 microns or greater at 1310 nm wavelength and a cable cutoff of less than or equal to about 1260 nm.

An optical fiber includes: a center core; an inner ring layer, located outside of the center core in a radial direction, that has a refractive index lower than a refractive index of the center core; an outer core, located outside of the inner ring layer in the radial direction, that has a refractive index higher than the refractive index of the inner ring layer; and an outer ring layer, located outside of the outer core in the radial direction, that has a refractive index lower than the refractive index of the outer core. A relative refractive index difference Δ.sub.CF between the center core and the inner ring layer varies along a longitudinal direction such that the relative refractive index difference Δ.sub.CF at a location along the longitudinal direction is smaller than a relative refractive index difference Δ.sub.PF between the outer core and the outer ring layer.

The invention is related to devices that couple light into and out of concentric multicore fibers (MCFs). One embodiment of the invention is directed to a multiplexing/demultiplexing coupler, formed using at least two diffractive optical elements, so that light from one of the cores of the concentric MCF exits the coupler along a first axis and the light from another of the cores of the MCF exits coupler along another axis displaced form the first axis. In another embodiment, an add/drop filter includes at least one diffractive optical element, and directs light from one core of the concentric MCF to one fiber and light from one or more other cores of the concentric MCF to another fiber. In another embodiment, a mixing coupler transmits light from inner and outer cores of a first concentric MCF respectively to outer and inner cores of a second concentric MCF.

The present disclosure provides an optical fibre. The optical fibre includes a core, an inner cladding, a first trench region, an intermediate cladding, a second trench region, and an outer cladding. The core has a first radius. The inner cladding is defined by the first radius and a second radius of the optical fibre. The first trench region is defined by the second radius and a third radius. The first trench region. The intermediate cladding is defined by the third radius and a fourth radius. The second trench region is defined by the fourth radius and a fifth radius. The outer cladding is defined by the fifth radius and a sixth radius.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nanopolymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nanopolymer layers in a tubular shape.

A new type of all-silica optical fiber is described; a Structured Silica Clad Silica (SSCS) optical fiber, whose cladding is structured to provide mode mixing within the core; and/or to have an average effective refractive index. Its cross-section is essentially symmetrical, it can be used, among other objects, to provide flatter, more speckle-free outputs from fiber lasers, or other limited mode photonic sources. Building the new fiber structure around a rare earth doped laser core provides a better fiber laser/amplifier for cladding pumping. The structured silica cladding contains paired layers, in which a down doped silica layer is followed by a layer of pure, or lesser down-doped, or even up-dope silica, and die number of paired layers is, typically, from 5 to about 25, and, generally, within the paired layers the ratio of thickness of the higher RI layer of silicate the down-doped silica is very broad, lying between about 0.0625 to about 16, depending on the intended use of the SSCS fibers. In some versions, the main core material can be up-doped silica with pure silica or down-doped silica as the primary second component.

The production and new type of preforms are presented which yield, upon drawing, new, class of optical fibers, improved, speckle-free output optical fibers. Useful fibers, providing speckle-free, smooth output with flat top transmission of light from gaussian or few mode sources are produced from preforms introduced herein. The unique production of these improved preforms is also presented. The preforms, and thus the fibers produced in varying core dimensions from about 100 μm to above 1000 μm, are based on a structured silica section of mode mixing area adjacent to the inner core, or in the case of non-circular core, within the core. Plasma Vapor Deposition process is modified to achieve the structured sections in a well-controlled manner. The structured sections are composed of a number of pairs of layers, where a thin down-doped layer is alternated with a much thicker core material layer. The ratio of the thickness of the core layer to the thickness of the down-doped layer is about 3 to 25. The number of paired layers is typically between about 8 to 30-layer pairs. The effective NA of the structured section is dependent on the particulars of the structured silica section and of the individual down-doped layer. Both circular inner core examples and non-circular core examples are possible and are discussed, herein.

In various embodiments, optical fibers have arrangements of core, annular core, and cladding regions enabling variation of beam shape and/or beam parameter product and may be utilized for the processing (e.g., welding, cutting, drilling, etc.) of various workpieces.