The invention relates to an optical fiber preform (20) comprising a primary preform (21) and one or more purified silica-based overclad layers (22) surrounding said primary preform (21), the purified silica-based overclad layers (22) comprising lithium and aluminium, and having a ratio between lithium concentration [Li] and aluminium concentration [Al] satisfying the following inequality:
1×10.sup.−3≤[Li]/[Al]≤20×10.sup.−3.

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.

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.

The disclosure relates to highly temperable colored glass compositions. The colored glass compositions have high coefficients of thermal expansion and high Young's moduli that advantageously absorb in the ultraviolet and/or blue wavelength ranges. Methods of making such glasses are also provided.

A silicate-based glass composition includes: 50-70 wt. % SiO.sub.2, 0.01-10 wt. % P.sub.2O.sub.5, 10-30 wt. % Na.sub.2O, 0.01-10 wt. % CaO, 0.01-10 wt. % MO, and 15-30 wt. % R.sub.2O, such that MO is the sum of MgO, CaO, SrO, BeO, and BaO, and R.sub.2O is the sum of Na.sub.2O, K.sub.2O, Li.sub.2O, Rb.sub.2O, and Cs.sub.2O.

The present invention discloses a glass-ceramic article and a glass-ceramic for an electric device cover plate, the glass-ceramic comprises, as a predominant crystalline phase, lithium silicate and the quartz crystalline phase, and has a composition expressed in weight percent including: SiO.sub.2: 65-85%, Al.sub.2O.sub.3: 1-15%, Li.sub.2O: 5-15%, ZrO.sub.2: 0.1-10%, P.sub.2O.sub.5: 0.1-10%, K.sub.2O: 0-10%, MgO: 0-10%, ZnO: 0-10%, and Na.sub.2O: 0-5%, wherein (SiO.sub.2+Al.sub.2O.sub.3+Li.sub.2O+ZrO.sub.2)/P.sub.2O.sub.5 is 40-90, the falling ball test height is 700 mm or more. By reasonable component design, the present invention achieves excellent mechanical properties of the glass-ceramic and the glass-ceramic article of the present invention and obtains the glass-ceramic or the glass-ceramic article suitable for electronic devices at a lower cost.

The disclosure relates to highly temperable colored glass compositions. The colored glass compositions have high coefficients of thermal expansion and high Young's moduli that advantageously absorb in the ultraviolet and/or blue wavelength ranges. Methods of making such glasses are also provided.

A system and process for forming a curved glass laminate article is provided. The process and system utilizes co-sagging of a stack of glass sheets of different thicknesses and different glass materials. During co-sagging the thicker glass layer is placed on top of the thinner glass layer. In this process, shape mismatch is avoided by selecting/controlling the glass materials of the sheets of glass such that the viscosity of the lower, thinner sheet during co-sagging is greater than the viscosity of the thicker glass sheet.

Methods of making a glass-based article including a surface feature thereon. Methods include arranging a glass-based substrate relative to a laser. Methods also include irradiating the glass-based substrate with laser beam with a light wavelength from about 2500 nm to about 3000 nm to grow a surface feature thereon.

The present invention discloses a glass-ceramic article and a glass-ceramic for an electric device cover plate, the glass-ceramic comprises, as a predominant crystalline phase, lithium silicate and the quartz crystalline phase, and has a composition expressed in weight percent including: SiO.sub.2: 65-85%, Al.sub.2O.sub.3: 1-15%, Li.sub.2O: 5-15%, ZrO.sub.2: 0.1-10%, P.sub.2O.sub.5: 0.1-10%, K.sub.2O: 0-10%, MgO: 0-10%, ZnO: 0-10%, and Na.sub.2O: 0-5%, wherein (SiO.sub.2+Al.sub.2O.sub.3+Li.sub.2O+ZrO.sub.2)/P.sub.2O.sub.5 is 40-90, the falling ball test height is 700 mm or more. By reasonable component design, the present invention achieves excellent mechanical properties of the glass-ceramic and the glass-ceramic article of the present invention and obtains the glass-ceramic or the glass-ceramic article suitable for electronic devices at a lower cost.