In a multicore optical fiber sensor, an absorptive material integrated into the cladding, or into a waveguide core not used for sensing, may facilitate sensing. The absorptive material is absorptive to light in a wavelength band in which the fiber sensor is configured to operate. Coating such a fiber sensor with a material whose refractive index is smaller than that of the cladding may be done with reduced signal mixing.

The present invention provides a method for manufacturing an optical fiber base material and an optical fiber base material, the method including: arranging a rod containing SiO.sub.2 family glass for core, in a container; pouring a SiO.sub.2 glass raw material solution for cladding layer and a hardener into the container, the glass raw material solution containing a hardening resin; solidifying the glass raw material solution through a self-hardening reaction; and then drying the solidified material and heating the solidified material in chlorine gas, to manufacture an optical fiber base material in which a SiO.sub.2 cladding layer is formed in an outer periphery of the rod containing SiO.sub.2 family glass for core.

The technology of this application relates to an erbium-doped fiber. The erbium-doped fiber can be used in the fields of amplifiers, optical communications, rare-earth-doped fiber preparation, and the like. A fiber core of the erbium-doped fiber includes a first layer and a second layer from inside to outside. The first layer includes a center of the fiber core. The second layer is an annulus, and an outer ring of the annulus is an outer ring of the fiber core. An average doping concentration of erbium ions of the first layer is higher than an average doping concentration of erbium ions of the second layer. An ASE can be reduced by reducing a doping concentration of erbium ions of the second layer, to further reduce a noise figure of the erbium-doped fiber and improve communications quality.

A method of manufacturing an optical fiber, the method includes drawing a first optical fiber preform at a first draw tension to produce a first alkali doped optical fiber and drawing the first optical fiber preform at a second draw tension to produce a second alkali doped optical fiber, measuring the attenuation of the first alkali doped optical fiber and the second alkali doped optical fiber such that the second alkali doped optical fiber has a lower attenuation. Additionally, the method includes setting the draw tension to the second draw tension and drawing a second optical fiber preform at the second draw tension to produce a third alkali doped optical fiber. The third alkali-doped optical fiber has an attenuation at 850 nm of about 1.50 dB/km or less and an attenuation at 1550 nm of about 0.155 dB/km or less.

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and an inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

A method and apparatus to manufacture a coherent bundle of scintillating fibers is disclosed. A method includes providing a collimated bundle having a glass preform with capillaries therethrough known in the industry as a glass capillary array, and infusing the glass capillary array with a scintillating polymer or a polymer matrix containing scintillating nanoparticles.

Disclosed herein is an optical fiber comprising a plurality of dopant concentration profiles in a core of the optical fiber; where the first dopant concentration and the second dopant concentration are each varied in a stepwise manner and wherein a ratio of the first dopant concentration to the second dopant concentration is operative to result in an interaction of a fundamental optical mode at a given wavelength with a plurality of acoustic modes thereby increasing a ratio of Brillouin Scattering intensity ratio of secondary, tertiary or quarternary peak relative to a Brillouin Scattering intensity of a primary peak to be greater than 0.4 in a Brillouin Scattering spectrum.

A method and apparatus to manufacture a coherent bundle of scintillating fibers is disclosed. A method includes providing a collimated bundle having a glass preform with capillaries therethrough known in the industry as a glass capillary array, and infusing the glass capillary array with a scintillating polymer or a polymer matrix containing scintillating nanoparticles.

Disclosed herein is an optical fiber comprising a plurality of dopant concentration profiles in a core of the optical fiber; where the first dopant concentration and the second dopant concentration are each varied in a stepwise manner and wherein a ratio of the first dopant concentration to the second dopant concentration is operative to result in an interaction of a fundamental optical mode at a given wavelength with a plurality of acoustic modes thereby increasing a ratio of Brillouin Scattering intensity ratio of secondary, tertiary or quarternary peak relative to a Brillouin Scattering intensity of a primary peak to be greater than 0.4 in a Brillouin Scattering spectrum.