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.

A multicore optical fiber including four cores arranged in a linear configuration, the centerline of each core being spaced from the centerline of an adjacent core by a distance x of about 30 microns or less, and each core having a relative refractive index .sub.1. A cladding surrounding each of the four cores, the cladding including an inner cladding region with a relative refractive index .sub.2, a depressed-index cladding region with a relative refractive index .sub.3, and an outer cladding region with a relative refractive index .sub.4, wherein .sub.1>.sub.2>.sub.3 and .sub.1>.sub.4>.sub.3. Furthermore, each core of the four cores has a mode field diameter, at a wavelength of 1310 nm, of about 8.1 microns or less, and cross talk between adjacent cores is about 18 dB or less at wavelengths of 1310 nm and 1550 nm per 2 km fiber length.

An MCF of the present embodiment has eight or more cores. A diameter of a common cladding is not more than 126 m. Optical characteristics of each core are as follows: a TL at a predetermined wavelength of 1310 nm is not more than 0.4 dB/km; an MFD at the predetermined wavelength is from 8.0 m to 10.1 m; a BL in a BR of not less than 5 mm or in the BR of not less than 3 mm and, less than 5 mm is not more than 0.25 dB/turn at the predetermined wavelength; 0 is from 1300 nm to 1324 nm; cc is not more than 1260 nm; an XT or XTs at the predetermined wavelength is not more than 0.001/km.

Optical fibers having a large effective area and a low cutoff wavelength are disclosed. Three main embodiments of the optical fiber allow for single-mode operation at wavelengths greater than 980 nm, and have a large effective area with low bend losses and low dispersion at 1310 nm. The large effective area optical fiber is expected to be particularly useful for data center applications due to its ability to efficiently optically couple with VCSELs and photonic integrated devices. Integrated systems and optical communication systems that employ the optical fibers are also disclosed.

Described and claimed herein are radiation curable compositions for coating an optical fiber, particularly primary coating compositions, wherein the composition possesses specified liquid glass transition temperatures, and/or viscosity ratios between, e.g., 25? C. and 85? C. Such compositions possess preferably high amounts of a reactive oligomer component with a backbone not derived from polypropylene glycol, preferably reactive oligomers with select diisocyanate constituents, one or more reactive diluent monomers, a photoinitiator, and optionally, one or more additives. Such compositions also are preferably sufficiently viscous at room temperature to ensure optimum optical fiber coating processability. Also described are methods of coating the radiation curable compositions elsewhere described, and the fiber optic coatings resulting therefrom.

A mode division multiplexing system that includes a transmitter system, a receiver system and an optical link that optically connects the transmitter and receiver systems. The optical link includes a rectangular-core optical fiber having a rectangular core with a short dimension and a long dimension. The rectangular-core optical fiber supports only a single mode in the short dimension and multiple modes in the long dimension. A method of transmitting optical signals includes converting single mode optical signals to respective multimode optical signals each having a select spatial mode as defined by the rectangular-core optical fiber. The multimode optical signals are multiplexed and transmitted from the transmitter system to the receiver system over the rectangular-core optical fiber where the multimode optical signals are demultiplexed and converted back to single mode optical signals, which are then detected by respective receivers. A rectangular-core optical fiber is also disclosed.

Disclosed herein are methods, apparatus, and systems for perturbing an optical beam propagating within a first length of fiber to adjust one or more beam characteristics of the optical beam in the first length of fiber or a second length of fiber or a combination thereof, coupling the perturbed optical beam into a second length of fiber and maintaining at least a portion of one or more adjusted beam characteristics within a second length of fiber having.

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 receptacle includes a fiber stub, a block, and a first elastic member. The fiber stub includes an optical fiber, and a ferrule provided on one end side of the optical fiber. The block is separated from the ferrule and has one end surface, an other end surface, and a through-hole extending from the one end surface to the other end surface. A portion of the optical fiber protrudes from the ferrule and is inserted into the through-hole. The first elastic member fixes the optical fiber in the through-hole. The portion of the optical fiber includes first to third portions. The second portion is provided between the first portion and the third portion. A core diameter at the first portion is smaller than a core diameter at the third portion. A core diameter at the second portion increases from the first portion toward the third portion.

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%.