A method for loading a blank composed of fused silica with hydrogen, including loading the blank at a first temperature (T.sub.1) and a first hydrogen partial pressure (p.sub.1), and further loading the blank at a second temperature (T.sub.2) which is different from the first temperature and at a second hydrogen partial pressure (p.sub.2) which is different from the first hydrogen partial pressure. The first and second temperatures (T.sub.1, T.sub.2) are lower than a limit temperature (T.sub.L) at which a thermal formation of silane in the fused silica of the blank commences. Also disclosed are a lens element produced from such a blank and a projection lens that includes at least one such lens element.

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.

A synthetic quartz glass substrate having a controlled hydrogen molecule concentration is prepared by (a) hot shaping a synthetic quartz glass ingot into a glass block, (b) slicing the glass block into a glass plate, (c) annealing the glass plate at 500-1,250 C. for 15-60 hours, (d) hydrogen doping treatment of the glass plate in a hydrogen gas atmosphere at 300-450 C. for 20-40 hours, and (e) dehydrogenation treatment of the glass plate at 200-400 C. for 5-10 hours.

Glass-based articles that include a hydrogen-containing layer extending from the surface of the article to a depth of layer. The hydrogen-containing layer includes a hydrogen concentration that decreases from a maximum hydrogen concentration to the depth of layer. The glass-based articles exhibit a high Vickers indentation cracking threshold. Glass compositions that are selected to promote the formation of the hydrogen-containing layer and methods of forming the glass-based article are also provided.

The invention concerns 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 comprises a core extending along the length of said longitudinal axis and a cladding region surrounding the core. At least the cladding region comprises 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 comprises hydrogen and/or deuterium. In at least the degradation resistant length section the PCF further comprises a main coating surrounding the cladding region, which main coating is hermetic for the hydrogen and/or deuterium at a temperature below Th, wherein Th is at least about 50? C., preferably 50? C.<Th<250? C.

A diffuser material of synthetically produced, pore-containing quartz glass and a method for the manufacture of a molded body consisting fully or in part thereof. The diffuser material has a chemical purity of at least 99.9% SiO.sub.2, a cristobalite content of not more than 1%, and a density in the range of 2.0 to 2.18 g/cm.sup.3. Starting therefrom, to indicate a diffuser material which is improved with respect to diffuse reflectivity with Lambertian behavior over a wide wavelength range, high material homogeneity and UV radiation resistance, the quartz glass has a hydroxyl group content in the range of at least 200 wt. ppm and at least 80% of the pores have a maximum pore dimension of less than 20 m.

Glass-based articles that include a hydrogen-containing layer extending from the surface of the article to a depth of layer. The hydrogen-containing layer includes a hydrogen concentration that decreases from a maximum hydrogen concentration to the depth of layer. The glass-based articles exhibit a high Vickers indentation cracking threshold. Glass compositions that are selected to promote the formation of the hydrogen-containing layer and methods of forming the glass-based article are also provided.

An optical fiber having an axial direction and a cross section perpendicular to the axial direction, and a method and preform for producing such an optical fiber. The optical fiber is adapted to guide light at a wavelength ?, and includes a core region, an inner cladding region surrounding said core region, and at least one of a first type of feature including a void and a surrounding first silica material. The core, the inner cladding region and the first type of feature extends along said axial direction over at least a part of the length of the optical fiber. The first silica material has a first chlorine concentration of about 300 ppm or less.

A multicore optical fiber that includes: a core that is formed of silica glass doped with at least fluorine, the core having a relative refractive index difference with respect to a refractive index of silica as a reference being 0.30% to 0.10%; and a clad that is formed of silica glass doped with at least fluorine. The clad includes a first clad surrounding an outer periphery of the core and a second clad provided outside the first clad. A relative refractive index difference between the first clad and the core is 0.8% or more. A refractive index of the second clad is higher than a refractive index of the first clad and lower than a refractive index of the core.

Glass-based articles that include a hydrogen-containing layer extending from the surface of the article to a depth of layer. The hydrogen-containing layer includes a hydrogen concentration that decreases from a maximum hydrogen concentration to the depth of layer. The glass-based articles exhibit a high Vickers indentation cracking threshold. Glass compositions that are selected to promote the formation of the hydrogen-containing layer and methods of forming the glass-based article are also provided.