The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

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.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

An electromagnetic waveguide, such as an optical fibre, including a hollow central core surrounded by a microstructured sheath formed by an assembly of elementary cells, the microstructured sheath also including at least two elementary cells, at least one intermediate element connecting the elementary cells, the intermediate element having a cross-section with an area less than or equal to 50% of the cross-sectional area of each of the cells that it connects, the intermediate element having a refractive index less than or equal to the refractive index of each of the elementary cells that it connects.

A microstructured optical fiber comprises a doped core region embedded in a cladding layer, and a plurality of longitudinal tubes, wherein a radial cross-section of the optical fiber comprises a central hexagonal portion comprising a plurality of holes arranged according to a hexagonal grid surrounding a core section. Each hole corresponds to a respective tube, within a hexagonal boundary of the grid, and the plurality of holes comprises holes of first and second types arranged in a biaxial mirror-symmetric configuration. The holes of the first type are arranged in two side holey structures comprising distinct sub-grids of the hexagonal grid, defined by respective outer boundaries corresponding to portions of the hexagonal boundary of the grid and respective inner boundaries. Outer tangential lines to the respective inner boundaries cross each other at the opposed side of the core with respect to the side of the respective side holey structure.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

The invention relates to a method of manufacturing an active optical fiber having a cladding and a doped core, as well as the active optical fiber equipped with the cladding and the doped core. The active optical fiber according to the invention is adapted to conduct and generate radiation having a wavelength and is provided with a cladding and a core containing at least one active dopant, characterized in that the core comprises elongate elements made of a first type of glass having a first refractive index n.sub.1 and elongate elements of a second type of glass having a second refractive index n.sub.2, oriented along the optical fiber and forming a compact bundle, wherein transverse dimensions of the elongate core elements are smaller than of the wavelength . Such optical fibers are used in laser generation and in amplification techniques.

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.

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.

We provide methods and apparatus for preparing crystalline-clad and crystalline core optical fibers with minimal or no breakage by minimizing the influence of thermal stress during a liquid phase epitaxy (LPE) process as well as the fiber with precisely controlled number of modes propagated in the crystalline cladding and crystalline core fiber via precisely controlling the diameter of crystalline fiber core with under-saturated LPE flux. The resulting crystalline cladding and crystalline core optical fibers are also reported.