The invention relates to a method for annealing of at least two wafers bonded via low-temperature direct bonding comprising heating the bonded wafers up to a first annealing temperature in the range of 100° C. to 500° C., preferably 150° C. to 400° C., even more preferred 150° C. to 200° C., holding the first annealing temperature in a range of 1 to 4 hours, preferably 1 to 3 hours, cooling down the bonded wafers to room temperature, re-heating the bonded wafers to a second annealing temperature in the range of 100° C. to 500° C., preferably 150° C. to 400° C., even more preferred 150° C. to 200° C., and cooling down the bonded wafers to room temperature.

A radiation-resistant laser optical fiber preform core rod at least includes one type of activated ion (Yb.sup.3+, Er.sup.3+) and one or more types of co-doped ion (Al.sup.3+, P.sup.5+, Ge.sup.4+, Ce.sup.3+, F.sup.−), and —OD group of 16-118 ppm. Irradiation resistance of core rod glass can be effectively improved by sequentially performing pre-treatments, i.e. deuterium loading, pre-irradiation and thermal annealing on a preform core rod. Electron paramagnetic resonance test shows that, under the same radiation condition, the radiation induced color center concentration in a preform core rod treated by the method above is lower than in an untreated core rod by one or more orders of magnitude. The obtained core rod can be used for preparing a radiation-resistant rare earth-doped silica fiber, and has the advantages of high laser slope efficiency, low background loss, being able to be used stably in a vacuum environment for a long time, for example.

A sheet of glass can be formed in a batch process by introducing molten glass onto a layer of molten tin within a tank. The tank may be outfitted with infrared emitters to control the amount of heat delivered to the tank while the sheet of glass is formed. A lower surface of the tank can have a three-dimensional shape, and the molten tin may be removed from the tank while the sheet of glass is ductile so that the sheet of glass is molded by the three-dimensional shape, thereby producing a shaped sheet of glass. The delivery of infrared energy to the tank may be facilitated by one or more ceramic glass surface.

A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A method of forming a glass sheet comprises: (a) forming a ribbon of glass from molten glass with a pair of forming rollers; (b) reducing horizontal temperature variability of the ribbon of glass to be 10° C. or less across 80 percent of an entire width of the ribbon of glass before the ribbon of glass cools to a glass transition temperature; (c) controlling a cooling rate of the ribbon of glass while the ribbon of glass moves vertically downward within a setting zone such that the ribbon of glass has a first average cooling rate before the ribbon of glass cools to the glass transition temperature and a second average cooling rate after the ribbon of glass cools to the glass transition temperature, the first average cooling rate being less than the second average cooling rate; and (d) separating a glass sheet from the ribbon of glass.

An environment-friendly glass material, including components like SiO.sub.2, ZnO, alkali metal oxide and S, but does not contain Cd, wherein when the thickness of the environment-friendly glass material is 3 mm, the cutoff wavelength is above 550 nm, the transmittance at 800-850 nm is above 75%, the transmittance at 850-900 nm is above 80%, the transmittance at 900-1000 nm is above 83%, and the transmittance at 1000-2000 nm is above 85%. Through rational component design, the glass material of the present invention realizes environmental protection, UV and visible light cutoff, and high near-infrared transmittance at the same time.

An environment-friendly glass material, including components like SiO.sub.2, ZnO, alkali metal oxide and S, but does not contain Cd, wherein when the thickness of the environment-friendly glass material is 3 mm, the cutoff wavelength is above 550 nm, the transmittance at 800-850 nm is above 75%, the transmittance at 850-900 nm is above 80%, the transmittance at 900-1000 nm is above 83%, and the transmittance at 1000-2000 nm is above 85%. Through rational component design, the glass material of the present invention realizes environmental protection, UV and visible light cutoff, and high near-infrared transmittance at the same time.

In a laser irradiation apparatus 1 according to one embodiment, each of first and second flotation units 30a, 30b includes a base 31, and a porous plate 32 bonded to an upper surface of the base 31 by an adhesive layer 34, the base 31 includes a rising portion 312 protruding upward at an outer periphery facing at least the gap, and the porous plate 32 includes a cutout portion 321 configured to fit to the rising portion 312, and the adhesive layer 34 is formed along an inner wall of the rising portion 312 having fitted to the cutout portion 321.

In a laser irradiation apparatus 1 according to one embodiment, each of first and second flotation units 30a, 30b includes a base 31, and a porous plate 32 bonded to an upper surface of the base 31 by an adhesive layer 34, the base 31 includes a rising portion 312 protruding upward at an outer periphery facing at least the gap, and the porous plate 32 includes a cutout portion 321 configured to fit to the rising portion 312, and the adhesive layer 34 is formed along an inner wall of the rising portion 312 having fitted to the cutout portion 321.