Abstract: A multi-clad optical fiber is provided. The fiber includes, concentrically and radially outwards from the center of the optical fiber, a core doped with at least one rare-earth dopant material, a pedestal cladding structure, an inner cladding and an outer cladding. The pedestal cladding structure includes a pedestal layer having a refractive index smaller than a refractive index of the core, and a raised index layer having a refractive index larger than the refractive index of the pedestal layer. The raised index layer has a thickness and a refractive index which preserve the confinement of the core mode in the core and minimize the overlap of one or more pedestal modes with the core.

Abstract: A composite material for sensing a chemical species in a medium is provided. The composite material includes a polymer having a glass transition temperature, a porosity promoter dispersed in the polymer in an amount such that the chemical species is transportable from the medium into the composite material at a temperature below the glass transition temperature, and a chemical indicator dispersed in the composite material, the chemical indicator providing an optical response varying with a concentration of the chemical species in the composite material.

Abstract: A multi-clad optical fiber is provided. The fiber includes, concentrically and radially outwards from the center of the optical fiber, a core doped with at least one rare-earth dopant material, a pedestal cladding structure, an inner cladding and an outer cladding. The pedestal cladding structure includes a pedestal layer having a refractive index smaller than a refractive index of the core, and a raised index layer having a refractive index larger than the refractive index of the pedestal layer. The raised index layer has a thickness and a refractive index which preserve the confinement of the core mode in the core and minimize the overlap of one or more pedestal modes with the core.

Abstract: Needle assemblies and analysis systems for collection and optical interrogation of a biological sample is provide. The needle assembly includes a needle hub and a needle tip. A shaft portion extends between the needle hub and the needle tip. The shaft portion includes a cavity extending from the needle hub to the needle tip. The cavity includes a sample-receiving region opened at the needle tip. In some embodiments, the shaft portion includes a cladding structure surrounding the cavity and configured for longitudinal light guidance. In other embodiments, the shaft portion includes an optical window in line-of-sight alignment with the sample-receiving region. The needle assembly may advantageously be used to collect, within the sample receiving region, a biological sample from a biological medium and perform an optical interrogation of this sample directly in the needle assembly.

Abstract: A composite material for sensing a chemical species in a medium is provided. The composite material includes a polymer having a glass transition temperature, a porosity promoter dispersed in the polymer in an amount such that the chemical species is transportable from the medium into the composite material at a temperature below the glass transition temperature, and a chemical indicator dispersed in the composite material, the chemical indicator providing an optical response varying with a concentration of the chemical species in the composite material.

Abstract: A multicore optical fiber includes a cladding and multiple cores disposed in the cladding. Each core has a light-guiding path and follows a helical trajectory about a fiber axis. The multicore fiber also includes a set of discrete lateral coupling zones, which are longitudinally distributed and azimuthally aligned with respect to the fiber axis. Each lateral coupling zone forms an optical coupling path, which enables at least one of lateral in-coupling and out-coupling of light between a corresponding one of the cores and an exterior of the multicore fiber. An optical probing system for light delivery to and/or light collection from a probed region includes a multicore optical fiber to enable coupling of guided light out of the cores for delivery to the probed region and/or collection of light from the probed region for coupling into one of the cores.

Abstract: A multicore optical fiber includes a cladding and multiple cores disposed in the cladding. Each core has a light-guiding path and follows a helical trajectory about a fiber axis. The multicore fiber also includes a set of discrete lateral coupling zones, which are longitudinally distributed and azimuthally aligned with respect to the fiber axis. Each lateral coupling zone forms an optical coupling path, which enables at least one of lateral in-coupling and out-coupling of light between a corresponding one of the cores and an exterior of the multicore fiber. An optical probing system for light delivery to and/or light collection from a probed region includes a multicore optical fiber to enable coupling of guided light out of the cores for delivery to the probed region and/or collection of light from the probed region for coupling into one of the cores.

Abstract: A microstructured optical fiber exhibiting enhanced circularity of the guided light mode is provided. The microstructured optical fiber includes a light-guiding core and a primary cladding surrounding the core wherein the primary cladding has a plurality of holes arranged in hexagonal unit cells defining an Archimedean-like lattice. Preferably, the core is defined by a break in a center of the Archimedean-like lattice, the break being characterised by an absence of at least one of the unit cells. Also preferably, each of the unit cells has seven holes arranged in a centred hexagon. A method of making the microstructured optical fiber is also provided. The method includes fabricating a fiber preform by stacking a plurality of canes around a rod, each cane having a number of holes arranged in a unit cell defining an Archimedean-like lattice, and drawing said fiber preform into the microstructured optical fiber.

Abstract: A method for manufacturing a polarization-maintaining optical fiber is provided. The method includes (a) making a fiber preform by providing in an over-cladding tube: a core rod having an inner core and a cladding surrounding the inner core; at least one stress-applying part (SAP) disposed adjacent to the core rod along an outer periphery of the cladding thereof and having a coefficient of thermal expansion different from that of the cladding; inner filler rods arranged along the outer periphery of the core rod at positions where the SAP is not disposed and having a coefficient of thermal expansion different from that of the SAP; and a plurality of outer filler rods arranged adjacent the over-cladding tube between the over-cladding tube and inner filler rods, SAP and core rod, and consisting of a same material as the over-cladding tube; and (b) drawing the fiber preform to obtain the optical fiber.

Abstract: A microstructured optical fiber exhibiting enhanced circularity of the guided light mode is provided. The microstructured optical fiber includes a light-guiding core and a primary cladding surrounding the core wherein the primary cladding has a plurality of holes arranged in hexagonal unit cells defining an Archimedean-like lattice. Preferably, the core is defined by a break in a center of the Archimedean-like lattice, the break being characterised by an absence of at least one of the unit cells. Also preferably, each of the unit cells has seven holes arranged in a centred hexagon. A method of making the microstructured optical fiber is also provided. The method includes fabricating a fiber preform by stacking a plurality of canes around a rod, each cane having a number of holes arranged in a unit cell defining an Archimedean-like lattice, and drawing said fiber preform into the microstructured optical fiber.