A method for manufacturing an optical fiber preform includes: producing a core preform including a core portion made of transparent glass and a first cladding layer obtained by adding fluorine to the core portion; and forming, on an outer periphery of the first cladding layer, a second cladding layer made of glass having a refractive index higher than that of the first cladding layer. Further, a refractive index profile is formed in the first cladding layer due to a fluorine concentration profile, the refractive index profile being provided at least near a boundary surface with the second cladding layer and having a profile such that a refractive index difference between a refractive index of the first cladding layer and a refractive index of the second cladding layer decreases in accordance with a reduction in a distance from the boundary surface with the second cladding layer.

A solution is provided comprising boron nitride nanotubes (BNNTs) in a liquid solvent. An optical waveguide, such as an optical fiber, is contacted with the solution so as to form a layer of the solution supported on at least a portion of the optical waveguide. The liquid solvent is then removed from the layer of the solution supported on the optical waveguide in order to form a coating of the BNNTs on the optical waveguide. Further provided is a BNNT coated optical waveguide for use as a sensor.

The invention concerns a Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and comprises a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region comprises a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF comprises hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further comprises a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below Th, wherein Th is at least about 50° C., preferably 50° C.<Th<250° C.

A method is described of manufacturing an optical sensing element for detecting a presence and/or determining a concentration of an analyte in a fluid medium, in particular in an aqueous medium. The optical sensing element includes an optical waveguide (e.g. an optical fiber) comprising an optically transparent material for guiding light through the sensing element along a flightpath. The optical sensing element further includes an inorganic coating for adsorbing the analyte from the fluid medium and an adhesion promotion layer formed between the optical waveguide and the inorganic coating. The adhesion promotion layer includes an adhesion promotion material for promoting adhesion of the inorganic material.

Method and apparatus for producing metal-coated optical fiber involves feeding a length of glass fiber through a first solution bath so as to plate a first predetermined metal on the glass fiber via electroless deposition. The length of glass fiber is passed continuously from the first solution bath to a second solution bath adapted to plate thereon a second predetermined metal via electrolytic plating such that the optical fiber contacts an electrode only after at least some of the second predetermined metal has been applied. The length of glass fiber may be passed continuously from the second solution bath to a third solution bath adapted to plate thereon a third predetermined metal via electrolytic plating.

A high-density optical fiber ribbon is formed by two or more cladding-strengthened glass optical fibers each having an outer surface and that do not individually include a protective polymer coating. A common protective coating substantially surrounds the outer surfaces of the two or more cladding-strengthened glass optical fibers so that the common protective coating is common to the two or more cladding-strengthened glass optical fibers. A fiber ribbon cable is formed by adding a cover assembly to the fiber ribbon. A fiber ribbon interconnect is formed adding one or more optical connectors to the fiber ribbon or fiber ribbon cable. Optical data transmission systems that employ the fiber ribbon to optically connect to a photonic device are also disclosed. Methods of forming the cladding-strengthened glass optical fibers and the high-density optical fiber ribbons are also disclosed.

A solution is provided comprising boron nitride nanotubes (BNNTs) in a liquid solvent. An optical waveguide, such as an optical fiber, is contacted with the solution so as to form a layer of the solution supported on at least a portion of the optical waveguide. The liquid solvent is then removed from the layer of the solution supported on the optical waveguide in order to form a coating of the BNNTs on the optical waveguide. Further provided is a BNNT coated optical waveguide for use as a sensor.

A Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein T.sub.h is at least about 50° C., preferably 50° C.<T.sub.h<250° C.

A photodarkening-resistant ytterbium-doped quartz optical fiber and a method for prpearing such a fiber are provided. Glass of a photodarkening-resistant ytterbium-doped quartz optical fiber core rod includes at least Yb.sub.2O.sub.3, Al.sub.2O.sub.3, P.sub.2O.sub.5, SiO.sub.2. The proportions of Yb.sub.2O.sub.3, Al.sub.2O.sub.3, and P.sub.2O.sub.5 in the entire substance are Yb.sub.2O.sub.3: 0.05-0.3 mol %, Al.sub.2O.sub.3: 1-3 mol %, and P.sub.2O.sub.5: 1-5 mol %, respectively. In the preparation method for the photodarkening-resistant ytterbium-doped quartz optical fiber, a sol-gel method and an improved chemical vapor deposition method are combined. By using the molecular-level doping uniformity and the low preparation loss thereof respectively, ytterbium ions, aluminum ions and phosphorus ions are effectively doped in a quartz matrix, thereby effectively solving the problems in the optical fiber of high loss, photodarkening caused by cluster or the like, and a central refractive index dip.

A Photonic Crystal Fiber (PCF) a method of its production and a supercontinuum light source comprising such PCF. The PCF has a longitudinal axis and includes a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region includes a plurality of microstructures in the form of inclusions extending along the longitudinal axis of the PCF in at least a microstructured length section. In at least a degradation resistant length section of the microstructured length section the PCF includes hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further includes a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below T.sub.h, wherein Th is at least about 50° C., preferably 50° C.<Th.sub.h<250° C.