Laser waveguides, methods and systems for forming a laser waveguide are provided. The waveguide includes an inner cladding layer surrounding a central axis and a glass core surrounding and located outside of the inner cladding layer. The glass core includes a laser-active material. The waveguide includes an outer cladding layer surrounding and located outside of the glass core. The inner cladding, outer cladding and/or core may surround a hollow central channel or bore and may be annular in shape.

An amplification optical fiber according to the present invention includes: a core doped with an active element, through which multi-mode light propagates; an inner cladding that surrounds the core and has a refractive index lower than that of the core; and an outer cladding that surrounds the inner cladding and has a refractive index lower than that of the inner cladding. The inner cladding has a polygonal outline in a cross section perpendicular to the longitudinal direction, and the inner cladding has a permanent twist applied by turning around the central axis of the core.

A small core-diameter graded-index optical fiber include a core layer and a cladding having an inner cladding layer, a depressed cladding layer, and an outer cladding layer from inside to outside thereof. The core layer has a parabolic refractive index profile with a distribution index in a range of 1.9-2.1, a radius in a range of 10-21 m, and a 1 max in a range of 0.7-1.7% at a core layer center, and is a silica glass layer co-doped with germanium, phosphorus, and fluoride. The inner cladding layer is a pure silica layer or an F-doped silica glass layer, and has a unilateral width in a range of 0.5-5 m and a 2 in a range of 0.4-0%. The depressed cladding layer has a unilateral width in a range of 2-10 m and a 3 in a range from 0.8% to 0.2%. The outer cladding layer is a pure silica glass layer.

Laser waveguides, methods and systems for forming a laser waveguide are provided. The waveguide includes an inner cladding layer surrounding a central axis and a glass core surrounding and located outside of the inner cladding layer. The glass core includes a laser-active material. The waveguide includes an outer cladding layer surrounding and located outside of the glass core. The inner cladding, outer cladding and/or core may surround a hollow central channel or bore and may be annular in shape.

The present disclosure provides a few mode optical fiber (100). The few mode optical fiber (100) includes a core region (102). A core region (102) defined by a region around a central longitudinal axis (116) of the few mode optical fiber (100). In addition, the core region (102) has a first annular region (106) extended from central longitudinal axis (116) to radius r.sub.1, a second annular region (108) extended from radius r.sub.1 to radius r.sub.2, a third annular region (110) extended from radius r.sub.2 to radius r.sub.3, a fourth annular region (112) extended from radius r.sub.3 to radius r.sub.4 and a fifth annular region (114) extended from radius r.sub.4 to radius r.sub.5. Also, the few mode optical fiber (100) has a cladding defined by the sixth annular region (104) extended from radius r.sub.5 to radius r.sub.6.

A high bandwidth radiation-resistant multimode optical fiber includes a core and a cladding layer surrounding the core. The core is a fluorine-doped quartz glass layer with a graded refractive index distribution and a distribution power exponent of 1.7-2.2. The core has R1 of 15-35 m and 1%min of 0.8% to 1.2%. The cladding layer has an inner cladding layer having R2 of 15-38 m and 2% of 0.8% to 1.2% and/or a depressed inner cladding layer having R3 of 15-55 m and 3 of 1.0% to 1.4%, an intermediate cladding layer having R4 of 15.5-58 m and 4 of 0.7% to 0.2% a depressed cladding layer hasving R5 of 16-60 m and 5 of 0.8% to 1.2%, and an outer cladding layer sequentially formed from inside to outside. The outer cladding layer is a pure silica glass layer.

An optical fiber device may include a unitary core including a primary section and a secondary section, wherein at least a portion of the secondary section is offset from a center of the unitary core, wherein the unitary core twists about an optical axis of the optical fiber device along a length of the optical fiber device, and wherein a refractive index of the primary section is greater than a refractive index of the secondary section; and a cladding surrounding the unitary core.

In various embodiments, the beam parameter product and/or beam shape of a laser beam is adjusted by directing the laser beam across a path along the input end of a cellular-core optical fiber. The beam emitted at the output end of the cellular-core optical fiber may be utilized to process a workpiece.

The present disclosure provides a few mode optical fiber. The few mode optical fiber includes a core region. A core region defined by a region around a central longitudinal axis of the few mode optical fiber. In addition, the core region has a first annular region extended from central longitudinal axis to radius r.sub.1, a second annular region extended from radius r.sub.1 to radius r.sub.2, a third annular region extended from radius r.sub.2 to radius r.sub.3, a fourth annular region extended from radius r.sub.3 to radius r.sub.4 and a fifth annular region extended from radius r.sub.4 to radius r.sub.5. Also, the few mode optical fiber has a cladding defined by the sixth annular region extended from radius r.sub.5 to radius r.sub.6.

The present disclosure provides a few mode optical fiber (100). The few mode optical fiber (100) includes a core region (102). A core region (102) defined by a region around a central longitudinal axis (116) of the few mode optical fiber (100). In addition, the core region (102) has a first annular region (106) extended from central longitudinal axis (116) to radius r.sub.1, a second annular region (108) extended from radius r.sub.1 to radius r.sub.2, a third annular region (110) extended from radius r.sub.2 to radius r.sub.3, a fourth annular region (112) extended from radius r.sub.3 to radius r.sub.4 and a fifth annular region (114) extended from radius r.sub.4 to radius r.sub.5. Also, the few mode optical fiber (100) has a cladding defined by the sixth annular region (104) extended from radius r.sub.5 to radius r.sub.6.