A measurement apparatus, including: a tapered optical fiber, the tapered optical fiber having an input to receive radiation and having an output to provide spectrally broadened output radiation toward a measurement target, the tapered optical fiber configured to spectrally broaden the radiation received at the input; and a detector system configured to receive a redirected portion of the output radiation from the measurement target.

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 a glass fiber and a coating resin covering an outer periphery of the glass fiber. The glass fiber includes a core and a cladding. An outer diameter of the glass fiber is 99 m or larger and 101 m or smaller. The coating resin includes a cured material of an ultraviolet curing resin composition. An outer diameter of the coating resin is 160 m or larger and 170 m or smaller. A mode field diameter for light having a wavelength of 1310 nm is 7.2 m or larger and 8.2 m or smaller. Bending loss at a wavelength of 1550 nm when wound in a ring shape having a radius of 10 mm is 0.1 dB/turn or less. Bending loss at the wavelength of 1550 nm when wound in the ring shape having the radius of 7.5 mm is 0.5 dB/turn or less.

Disclosed herein are methods, apparatus, and systems for providing an optical beam delivery system, comprising an optical fiber including a first length of fiber comprising a first RIP formed to enable, at least in part, modification of one or more beam characteristics of an optical beam by a perturbation assembly arranged to modify the one or more beam characteristics, the perturbation assembly coupled to the first length of fiber or integral with the first length of fiber, or a combination thereof and a second length of fiber coupled to the first length of fiber and having a second RIP formed to preserve at least a portion of the one or more beam characteristics of the optical beam modified by the perturbation assembly within one or more first confinement regions. The optical beam delivery system may include an optical system coupled to the second length of fiber including one or more free-space optics configured to receive and transmit an optical beam comprising the modified one or more beam characteristics.

An optical fiber includes: a core that includes quartz glass doped with a core updopant; an inner cladding that includes quartz glass doped with a cladding updopant and a downdopant and that covers a circumferential surface of the core; and an outer cladding that includes quartz glass and that covers an outer circumferential surface of the inner cladding. A refractive index of the inner cladding is substantially equal to a refractive index of the outer cladding. The inner cladding contains the cladding updopant at a concentration such that a refractive index increase rate ascribed to the cladding updopant falls within a range of 0.25% to 0.5%.

Disclosed herein are methods, apparatus, and systems for providing an optical beam delivery device, comprising a first length of fiber comprising a first RIP formed to enable modification of one or more beam characteristics of an optical beam by a perturbation device and a second length of fiber having a second RIP coupled to the first length of fiber, the second RIP formed to confine at least a portion of the modified beam characteristics of the optical beam within one or more confinement regions.

A method for forming an article includes providing a material having a first material property; forming a melt pool by exposing the material to an optical beam having at least one beam characteristic, wherein the melt pool has at least one melt pool property determinative of a second material property of the material; and modifying the at least one beam characteristic in response to a change in the melt pool property.

A method for forming an article includes providing a material having a first material property; forming a melt pool by exposing the material to an optical beam having at least one beam characteristic, wherein the melt pool has at least one melt pool property determinative of a second material property of the material; and modifying the at least one beam characteristic in response to a change in the melt pool property.

There are provided a multi-core optical fiber including four step-index type cores with a standard cladding diameter and having excellent mass productivity, quality, and yield while meeting desired specifications, and a design method thereof.

A multi-core optical fiber according to the present disclosure includes: four cores arranged in a square lattice shape along a longitudinal direction, each of the four cores having a step-index type refractive index distribution with a radius a; and a cladding region having a lower refractive index than that of each core and a diameter of 1251 m and provided on an outer peripheral portion of each core, where an absolute value of a relative refractive index difference between each core and the cladding region is . The four cores are arranged so that a relationship between a minimum distance (OCT) from the center of each core to an outer periphery of the cladding region, a minimum value of spacing between the cores, and the MFD at a wavelength of 1310 nm satisfies Formula C1, and the radius a of each core and the relative refractive index difference between the core and the cladding region are set.

[Formula C1]

OCT3.73MFD+3.43

5.28MFD+83.54(C1)

Disclosed herein are methods, apparatus, and systems for providing an optical beam delivery system, comprising an optical fiber including a first length of fiber comprising a first RIP formed to enable, at least in part, modification of one or more beam characteristics of an optical beam by a perturbation assembly arranged to modify the one or more beam characteristics, the perturbation assembly coupled to the first length of fiber or integral with the first length of fiber, or a combination thereof and a second length of fiber coupled to the first length of fiber and having a second RIP formed to preserve at least a portion of the one or more beam characteristics of the optical beam modified by the perturbation assembly within one or more first confinement regions. The optical beam delivery system may include an optical system coupled to the second length of fiber including one or more free-space optics configured to receive and transmit an optical beam comprising the modified one or more beam characteristics.