A method of making a microstructured optical fiber including loading the core and cladding materials of the fiber with hydrogen and deuterium at a loading temperature; annealing the fiber at a selected temperature T.sub.anneal; pumping the fiber with radiation; and reducing the temperature of the fiber and storing the fiber at the reduced temperature before the step of pumping the fiber; and wherein the method allows the hydrogen and the deuterium to become bound to the core material and the cladding material.

A method of making a microstructured optical fiber including loading the core and cladding materials of the fiber with hydrogen and deuterium at a loading temperature; annealing the fiber at a selected temperature T.sub.anneal; pumping the fiber with radiation; and reducing the temperature of the fiber and storing the fiber at the reduced temperature before the step of pumping the fiber; and wherein the method allows the hydrogen and the deuterium to become bound to the core material and the cladding material.

An illumination device includes: an optical fiber, the optical fiber allowing light emitted from a light source to be introduced at a first end portion thereof and to be guided through the optical fiber while emitting a portion of the light through a side surface of the optical fiber; a light-transmissive tube, the light-transmissive tube covering the side surface of the optical fiber such that a gap is located between the tube and the side surface of the optical fiber; and a light-shielding cap covering a second end portion of the tube at a side opposite the light source such that a space is located between a bottom portion of the cap and the second end portion of the tube. A second end portion of the optical fiber projects past the second end portion of the tube and is located at an inner side of the cap.

An optical fiber having an axial direction and a cross section perpendicular to the axial direction, and a method and preform for producing such an optical fiber. The optical fiber is adapted to guide light at a wavelength ?, and includes a core region, an inner cladding region surrounding said core region, and at least one of a first type of feature including a void and a surrounding first silica material. The core, the inner cladding region and the first type of feature extends along said axial direction over at least a part of the length of the optical fiber. The first silica material has a first chlorine concentration of about 300 ppm or less.

An optical fiber with wide bandwidth and high gain in an O+E band and a regulation method thereof are disclosed. The optical fiber includes a core and a cladding (0). The core includes a first loose layer (1), a first core layer (2), a second loose layer (3), a second core layer (4) and an inner core (5) from outside to inside. The first loose layer (1) and the second loose layer (3) are made of a silica material doped with high-refractive-index GeO.sub.2 and P.sub.2O.sub.5. In the first core layer (2) and the second core layer (4), Al.sub.2O.sub.3, bismuth oxide and PbO are sequentially doped. The gain performance of the optical fiber is controlled by adjusting doping molar ratios of Al.sub.2O.sub.3, bismuth oxide and PbO. The co-doped silica optical fiber maintains fiber gains exceeding 15 dB in a wavelength range of 1260 to 1460 nm.

A single-core polarization-maintaining dispersion compensation micro-structured optical fiber comprises a fiber core, a first layer of air holes surrounding the fiber core, the cladding defects on the x-axis, the cladding defects on the y-axis, and the cladding. The air holes in the fiber cross section are arranged in the equilateral triangle lattice. Three consecutive air holes are omitted to form a solid area. This solid area is the fiber core. There are two cladding defects along the x-axis. Their centers are respectively located at the two vertices of the hexagon on the x-axis, which is formed by the fourth air hole ring from the core exclusive the central air hole. Each cladding defect along the x-axis contains 7 air holes and goes through from the core by only 1 layer of air holes. There are also two cladding defects along the y-axis.

The purpose of the present invention is to provide an optical fiber evaluation equipment and an optical fiber evaluation method that evaluate the center of a cladding of an MCF and a deviation of the center of each core of the MCF from a design value with ease and high accuracy. The optical fiber evaluation equipment according to the present invention approximates the outside diameter of a cladding by a circle, based on a cross-sectional image of an MCF, and determines the center of the circle as the center of the cladding. In addition, the optical fiber evaluation equipment according to the present invention obtains the center coordinates of cores with an origin at the center of the circle, rotates the cross-sectional image so as to minimize a difference between the center coordinates and design coordinates of each core, and derives the minimum value thereof as the amount of deviation of the center of each core.

A hollow-core fibre (100) of non-bandgap type comprises a hollow core region (10) axially extending along the hollow-core fibre (100) and having a smallest transverse core dimension (D), wherein the core region (10) is adapted for guiding a transverse fundamental core mode and transverse higher order core modes, and an inner cladding region (20) comprising an arrangement of anti-resonant elements (AREs) (21, 21A, 21B) surrounding the core region (10) along the hollow-core fibre (100), each having a smallest transverse ARE dimension (d.sub.i) and being adapted for guiding transverse ARE modes, wherein the core region (10) and the AREs (21, 21A, 21B) are configured to provide phase matching of the higher order core modes and the ARE modes and the ARE dimension (d.sub.i) and the core dimension (D) are selected such that a ratio of the ARE and core dimensions (d.sub.i/D) is approximated to a quotient of zeros of Bessel functions of first kind (u.sub.lm,ARE/u.sub.lm,core), multiplied with a fitting factor in a range of 0.9 to 1.5, with m being the m-th zero of the Bessel function of first kind of order l, said zeros of the Bessel functions describing the LP.sub.lm ARE modes and LP.sub.lm higher order core modes, respectively. Furthermore, an optical device (200) including the hollow-core fibre (100) and a method of manufacturing the hollow-core fibre are described.

A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.

This disclosure relates to polarizing optical fibers and polarization maintaining optical fibers, including active and/or passive implementations. An embodiment includes a polarizing (PZ) optical fiber that includes stress applying parts (SAPs) disposed in a first cladding region, the SAPs comprising a material with a thermal expansion coefficient, ?.sub.SAP. A core region is at least partially surrounded by cladding features and the SAPs. The core includes glass with a thermal expansion coefficient, ?.sub.core. The arrangement of the SAPs satisfies: R.sub.sc=d.sub.SAP/D.sub.sc, where D.sub.sc is the SAP center to core center distance, and d.sub.SAP is the average SAP diameter, and d?=|?.sub.SAP??.sub.core|, and where Rsc and d? may be sufficiently large to induce stress birefringence into the core and to provide for polarized output. Active fibers in which a portion of the fiber is doped may be implemented for application in fiber lasers, fiber amplifiers, and/or optical pulse compressors.