Space division multiplexers can include adapters between multicore fibers with different core patterns and/or add-drop multiplexers for multicore fibers.

Example embodiments include an optical interrogation system with a sensing fiber having a single core, the single core having multiple light propagating modes. Interferometric apparatus probes the single core multimode sensing fiber over a range of predetermined wavelengths and detects measurement interferometric data associated with the multiple light propagating modes of the single core for each predetermined wavelength in the range. Data processing circuitry processes the measurement interferometric data associated with the multiple light propagating modes of the single core to determine one or more shape-sensing parameters of the sensing fiber from which the shape of the fiber in three dimensions can be determined.

Disclosed herein is a method for measuring temperature via distributed temperature sensing comprising transmitting light through a fiber optic cable; detecting backscattered light in the fiber optic cable, wherein the backscattered light comprises an anti-Stokes band and a Stokes band; calculating a ratio between an intensity of the anti-Stokes band and an intensity of the Stokes band; and using the calculated ratio to determine a temperature being sensed in the fiber optic cable; wherein the fiber optic cable comprises, from the center to the periphery; a central core having a refractive index that decreases progressively from a center of the central core to an edge of the core, wherein the refractive index follows an alpha profile; wherein a bandwidth-length product of the multimode optical fiber has a value greater than 2000 MHz-km at 1550 nm.

The laser-induced dispensing system includes a cartridge assembly having a supply reel for supplying a foil having a light transmissive layer wound around the supply reel, and a take-up reel for taking up the foil. There is provided a coating device for coating the foil by a donor material during a motion of the foil. The laser-induced dispensing system also includes an irradiation head having optics configured for focusing a laser beam. Additionally, a controller, for controlling the cartridge assembly to establish motion of the foil, and the optics to focus the laser beam onto the foil at a location downstream of the outlet of the coating device so as to release droplets of the donor material from the foil is provided.

A method of categorizing a group of multimode optical fibers, the method including comparing an effective modal bandwidth of a first multimode optical fiber with a first threshold, the first multimode optical fiber being in a group of multimode optical fibers meeting a first OM-standard and the first threshold being an effective modal bandwidth of the first multimode optical fiber. The method further including categorizing the first multimode optical fiber as meeting OM functional requirements of a second OM-standard if the effective modal bandwidth of the first multimode optical fiber is equal to or above the first threshold, wherein the second OM-standard is higher than the first OM-standard.

The present invention provides a method for converting the topological charge of an orbital angular momentum mode of light to an opposite topological charge by applying the light to a spool of optical fiber having a bend radius R and length L. The length of the fiber used to form the spool is defined by ½ the bend-induced 2π walk-off length L.sub.l,m.sup.b(2π). The length of the fiber L and the bend radius R of the spool may be adjusted to account for an ellipticity-induced 2π walk-off length L.sub.l,m.sup.3(2π). Using the proportionality rules, L.sub.l,m.sup.b(2π)∝R.sup.2l and L.sub.l,m.sup.3(2π)∝ε.sup.−l adjustments to account for ellipticity induced 2π walk-off length L.sub.l,m.sup.e(2π), or to account for a change in the bend radius ΔR of the spool can be easily determined.

A first multimode optical fiber carries a mode division multiplexed (MDM) optical signal. The MDM optical signal is transmitted into a second multimode fiber from the first multimode optical fiber. The first and second multimode fibers are coupled via a fiber connector. The lateral offset between the two fibers at the connector is less than 2 μm.

A mode equalization filter for reducing a difference in optical power between modes of signal light propagating inside FMFs of an MDM optical transmission scheme includes an FMF on the input side, a collimating lens, an ND filter, a condensing lens, and an FMF on the output side. The ND filter includes partial ND filters combined each other and having main surfaces placed in parallel to each other, a ring portion having a low transmittance is provided in a part of the partial ND filter, and a ring portion having a low transmittance is also provided in a part of the partial ND filter. When the ring portions have different aspects, and the partial ND filters are adjusted and set to be slidable in directions of axes, respectively, the partial ND filters have a property that the transmittance of each mode of the signal light differs and can obtain a function of a variable mode equalization filter.

The invention relates to a waveguide and a polarisation splitter based on said waveguide, in which a rotation of an angle greater than zero is applied to a plurality of sections of a core material and a plurality of sections of a covering material, thereby achieving an independent control of the refractive indices of a zero-order transverse electric mode and a zero-order transverse magnetic mode. This document also describes a manufacturing method of said waveguide which allows the birefringence of the light that passes through the waveguide.

An optical fiber rod (30) according to the present invention includes a center region (35), an outer region (31) formed around the center region (35), and an intermediate region (33) formed between the center region (35) and the outer region (31), and satisfies nA>nB>nC where nA is the refractive index of a material A produced by polymerization of a monomer ma, nB is the refractive index of a material B produced by polymerization of a monomer mb, and nC is the refractive index of a material C produced by polymerization of a monomer mc. The center region (35) is made of a material produced by polymerization of a monomer mixture containing the monomer ma, the outer region (31) is made of a material produced by polymerization of a monomer mixture containing the monomer mc, and the intermediate region (33) is made of a material produced by polymerization of a monomer mixture containing the monomer mb. The refractive index decreases in the order: the center region (35)>the intermediate region (33)>the outer region (31).