The wideband multimode co-doped optical fiber has a silica core co-doped with GeO.sub.2 and Al.sub.2O.sub.3. The GeO.sub.2 concentration is maximum at the fiber centerline and monotonically decreases radially out to the core radius. The Al.sub.2O.sub.3 concentration is minimum at the centerline and monotonically increases radially out to maximum concentration at the core radius. The cladding has an inner cladding region of relative refractive index Δ2, an intermediate cladding region having a relative refractive index Δ3, and an outer cladding region having a relative refractive index Δ4, wherein Δ3<Δ2, Δ4. The optical fiber has a bandwidth BW≥5 GHz.Math.km with a peak wavelength λ.sub.P within a wavelength range of 800 nm to 1200 nm and over a wavelength band Δλ of at least 100 nm.

Multimode optical fibers are disclosed herein. In some embodiment disclosed herein, a multimode optical fiber having a bandwidth of greater than 2 GHz.Math.km includes: a glass matrix having a front endface, a back endface, a length (L), a refractive index n.sub.20 and a central axis (AC); and a plurality of cores arranged within the glass matrix, wherein the plurality of cores run generally parallel to the central axis between the front and back endfaces and having respective refractive indices n.sub.50, wherein n.sub.50>n.sub.20, wherein the glass matrix serves as a common cladding for the plurality of cores so that each core and the common cladding define a waveguide, wherein each core is a single mode at an operating wavelength; and wherein any two cores have an center-to-center spacing s of 3 μm to 20 μm and a coupling coefficient of greater than 10 m.sup.−1 but less than 200 m.sup.−1.

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.

Glasses are provided that are highly transparent and have very good resistance to solarization. The resistance to solarization is favored to a special extent by the production method. The concentrations of reduced polyvalent ion species are reduced by targeted use of bubbling with an oxidizing gas. Methods for producing glasses and to the uses thereof, particularly as core glasses in optical waveguides, are also provided.

Glasses are provided that are highly transparent and have very good resistance to solarisation. The resistance to solarisation is favoured to a special extent by the production method. The concentrations of reduced polyvalent ion species are reduced by targeted use of bubbling with an oxidising gas. Methods for producing glasses and to the uses thereof, particularly as core glasses in optical waveguides, are also provided.

An aluminoborosilicate glass includes alkaline earth oxides and is substantially free of alkali oxides. The glass may be fusion formable and may be useful as a substrate or other article, such as with consumer and commercial electronic devices.

A photodarkening-resistant ytterbium-doped quartz optical fiber and a method for preparing 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.

The wideband multimode co-doped optical fiber has a silica core co-doped with GeO.sub.2 and Al.sub.2O.sub.3. The GeO.sub.2 concentration is maximum at the fiber centerline and monotonically decreases radially out to the core radius. The Al.sub.2O.sub.3 concentration is minimum at the centerline and monotonically increases radially out to maximum concentration at the core radius. The cladding has an inner cladding region of relative refractive index Δ2, an intermediate cladding region having a relative refractive index Δ3, and an outer cladding region having a relative refractive index Δ4, wherein Δ3<Δ2, Δ4. The optical fiber has a bandwidth BW≥5 GHz.Math.km with a peak wavelength λ.sub.P within a wavelength range of 800 nm to 1200 nm and over a wavelength band Δλ of at least 100 nm.

A manufacturing method for an optical fiber, includes: drawing, while heating in a heating furnace, a lower end of an optical fiber preform that is to be an optical fiber having a core consisting of silica glass containing a rare earth element compound. The heating furnace has a temperature profile in which a temperature of the heating furnace increases to a maximum temperature T.sub.max and then decreases from an upstream side of the heating furnace toward a downstream side of the heating furnace. The temperature profile has a changing point at which the temperature decreases more steeply on the downstream side from a position where the maximum temperature T.sub.max is reached. At the maximum temperature, a temperature of the silica glass is higher than or equal to a glass transition temperature and the silica glass is in a single phase.

An optical fiber includes a core, and a cladding. When a refractive index of silica glass is set as no, a refractive index of the core is set as n.sub.1, and a refractive index of the cladding is set as n.sub.2, a relative refractive index difference Δ defined by Expression (1):

Δ[%]=100×(n.sub.1.sup.2−n.sub.2.sup.2)/2n.sub.0.sup.2  (1)

is 0.2% or higher. A ratio of a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the cladding to a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the core is 0.06 or higher and 0.25 or lower.