The optical fiber offered is capable of not only restraining the attenuation due to glass defects, but also reducing the increase of manufacturing cost. The optical fiber is made of silica glass and includes a core and a cladding. The cladding encloses the core and has a refractive index smaller than that of the core. When the core is divided into inner core and outer core at half of the radius of the core, the average chlorine concentration of the inner core is larger than that of the outer core. The core includes any of the alkali metal group.

An amplification fiber which can generate a laser beam in a visible region even when a silica glass is used as a base material of a core of the amplification fiber is realized. An amplification fiber according to an embodiment of the present disclosure includes a core configured to generate a laser beam from an excitation beam in a visible region, and a cladding surrounding the core. The core is composed of a core material including Dy, one or more elements selected from Al, Ge, and P, and a silica glass.

Intermediate to high CTE glass compositions and laminates formed from the same are described. The glasses described herein have properties, such as liquidus viscosity or liquidus temperature, which make them particularly well suited for use in fusion forming processes, such as the fusion down draw process and/or the fusion lamination process. Further, the glass composition may be used in a laminated glass article, such as a laminated glass article formed by a fusion laminate process, to provide strengthened laminates via clad compression as a result of CTE mismatch between the core glass and clad glass.

A glass substrate for a high-frequency device, which contains, in terms of mole percent on the basis of oxides: 40 to 75% of SiO.sub.2; 0 to 15% of Al.sub.2O.sub.3; 13 to 23% of B.sub.2O.sub.3; 2.5 to 11% of MgO; and 0 to 13% of CaO, and having a total content of alkali metal oxides in the range of 0.001-5%, where at least one main surface of the glass substrate has a surface roughness of 1.5 um or less in terms of arithmetic average roughness Ra. and the glass substrate has a dielectric dissipation factor at 35 GHz of 0.007 or less.

Disclosed are biodegradable glass substrates that are useful as functional elements of solid-state devices. In particular, biodegradable glass substrates having a rapidly degradable glass and a slowly degradable glass provide a structural platform that completely dissolves following a desired operational lifetime of devices such as implanted electronic devices, implanted sensor devices, and optical fibers.

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.

The present invention relates to a glass substrate for a high-frequency device, which includes SiO.sub.2 as a main component, the glass substrate having a total content of alkali metal oxides in the range of 0.001-5% in terms of mole percent on the basis of oxides, the alkali metal oxides having a molar ratio represented by Na.sub.2O/(Na.sub.2O+K.sub.2O) in the range of 0.01-0.99, and the glass substrate having a total content of Al.sub.2O.sub.3 and B.sub.2O.sub.3 in the range of 1-40% in terms of mole percent on the basis of oxides and having a molar ratio represented by Al.sub.2O.sub.3/(Al.sub.2O.sub.3+B.sub.2O.sub.3) in the range of 0-0.45, in which at least one main surface of the glass substrate has a surface roughness of 1.5 nm or less in terms of arithmetic average roughness Ra, and the glass substrate has a dielectric dissipation factor at 35 GHz of 0.007 or less.

An optical fiber according to an embodiment includes a core, a cladding, and a coating layer. At the boundary between the core and the cladding, the local sound velocity decreases in the direction from the core side toward the cladding side. At least in the cladding, the local sound velocity changes continuously in a radial direction. Further, the line width of the Brillouin gain of the light beam guided by the fundamental mode is 60 MHz or more.

An optical fiber includes a core portion having a radius r.sub.C and a graded refractive index profile .sub.C having an alpha value greater than or equal to 1 and less than or equal to 8. The core portion includes a silica-based glass and a down-dopant, where a concentration of the down-dopant is graded such that the concentration of the down-dopant decreases from the radius r.sub.C towards the center of the core portion. The optical fiber comprises a cladding portion surrounding the core portion and having a relative refractive index .sub.OC that is less than a maximum refractive index .sub.Cmax of the core portion.

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.