The present disclosure provides a multi-core fiber (MCF) and manufacturing method thereof and an MCF marker (or marker). The MCF (100) comprises a plurality of cores (102) and a marker (108). Each core is associated with a core diameter (104) and a core-placement-radius (106) and the marker (108) is associated with a marker diameter (110) and a marker-placement-radius (112). The marker has a marker core (116) and a marker clad (118) with a D/d ratio between 5 to 20. During manufacturing, the MCF is drawn from a preform assembly (200) having a top hollow handle (202) with a handle thickness (114) attached on a top end of a glass preform (204) that has a plurality of core holes (206) and a marker hole (210), wherein the marker hole (210) is at least partially covered by the top hollow handle of the handle thickness (114).

A micro-structured optical fiber suitable for supercontinuum generation, a preform therefor, and a method of production thereof and a supercontinuum light source. The optical fiber includes a core microstructured length section L.sub.cm, which includes a micro-structured core region having at least a first region forming a central part of the core region and a second region surrounding the first region; and a cladding surrounding the core region; wherein the first and second regions are of a first and second silica material, respectively, which differs with respect to composition, and wherein the core region in at least a length part of the core microstructured length section L.sub.cm has a cross sectional diameter D.sub.cm perpendicular to the longitudinal axis which is about 8 μm or less.

An IR-transmitting glass fiber configured to include a holey-microstructured core and a cladding surrounding the core. Glass material used at least in the core is one of the heavy metal oxide glasses, where the glass network former is an oxide selected from GeO.sub.2, TeO.sub.2, Sb.sub.2O.sub.3, and Bi.sub.2O.sub.3, while each and every component of the fiber includes only an oxide glass material and is devoid of any other materials.

A microstructured multicore optical fibre (MMOF) includes a cladding in which a plurality of basic cells are formed that run along the MMOF. Each of the basic cells includes a core, and at least one of the basic cells is surrounded by a plurality of longitudinal areas that run parallel to the core along the MMOF and are arranged in a hexagonal arrangement around the core. The longitudinal areas are spaced by a lattice constant Λ. Sides of the hexagon can be shared with adjacent basic cells.

An anti-torsion solid-core polarization-maintaining photonic crystal fiber includes a cladding having an inner layer arranged around the core and an outer layer between the inner layer and the outer wall of the cladding. The inner layer has multi-layer air holes used to construct optical properties and two micron-size air holes arranged along the x-axis extending in the center producing form birefringence. The outer layer includes multi-layer air holes arranged radially along the y-axis. The size and arrangement of the multi-layer air holes in the outer layer cause the bending stiffness of the photonic crystal fiber along the x-axis to be different from that along the y-axis. While meeting the requirements of the optical properties of the fiber, the photonic crystal fiber possesses an anti-torsion ability due to the anisotropy of stress distribution in the radial direction, thereby reducing the non-reciprocal phase difference generated by the magneto-optic Faraday Effect.

A hollow core photonic bandgap optical fibre comprises: a cladding comprising capillaries in a hexagonal array and a hollow core formed by excluding a hexagonal group of nineteen capillaries from the centre of the hexagonal array. The core is inflated. A core size ratio is 1.26 or above, defined as a ratio of the core diameter to the cladding diameter normalized to the ratio of the core diameter to the cladding diameter in an undistorted hexagonal array; a first ring ratio is between 0.55 and 2.50, defined as a ratio of the length of radially aligned struts separating the capillaries of the first ring to the length of a strut in an undistorted hexagonal array; and a core node spacing is between 0.60 and 1.90, where defined as a ratio of a strut length around the core of a largest corner capillary and a strut length around the core of a smallest side capillary. The fabrication method comprises four different pressures for the core, corner capillary, side capillary and cladding.

A preform for making a vortex optical fiber comprises a glass cylinder formed substantially of silicone dioxide that defines a core portion along a longitudinal axis of the glass cylinder and a cladding portion surrounding the core portion. The glass cylinder further defines a plurality of holes running parallel to the longitudinal axis from a first end of the glass cylinder to a second end of the glass cylinder.

Rare earth doped fiber lasers can be robust and efficient sources of high quality light, but are usually limited to the highest gain transitions of the active species. But rare earths typically possess a multitude of potentially useful transitions that might be accessed if the dominant transition can be suppressed. In fiber lasers this suppression is complicated by the very high net gain the dominant transitions exhibit; effective suppression requires some mechanism distributed along the length of the fiber. We have developed a novel waveguide with resonant leakage elements that frustrate guidance at well-defined and selectable wavelengths. Based on this waveguide, we have fabricated a Large Mode Area Neodymium doped fiber with suppression of the four-level transition around 1060 nm, and demonstrated lasing on the three-level transition at 930 nm with good efficiency.

An Nd.sup.3+ optical fiber laser and amplifier operating in the wavelength range from 1300 to 1450 nm is described. The fiber includes a rare earth doped optical amplifier or laser operating within this wavelength band is based upon an optical fiber that guides light in this wavelength band. The waveguide structure attenuates light in the wavelength range from 850 nm to 950 nm and from 1050 nm to 1150 nm.

The present invention, as disclosed and described herein, in one aspect thereof comprises a preform for making a vortex optical fiber includes a glass cylinder formed substantially of silicone dioxide that defines a core portion along a longitudinal axis of the glass cylinder and a cladding portion surrounding the core portion. The glass cylinder further defines a plurality of holes running parallel to the longitudinal axis from a first end of the glass cylinder to a second end of the glass cylinder.