A co-doped optical fiber is provided having an attenuation of less than about 0.17 dB/km at a wavelength of 1550 nm. The fiber includes a core region in the fiber having a graded refractive index profile with an alpha of greater than 5. The fiber also includes a first cladding region in the fiber that surrounds the core region. Further, the core region has a relative refractive index of about −0.10% to about +0.05% compared to pure silica. In addition, the core region includes silica that is co-doped with chlorine at about 1.2% or greater by weight and fluorine between about 0.1% and about 1% by weight.

A glass substrate for a high-frequency device, which contains 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 alkaline earth metal oxides in the range of 0.1-13% in terms of mole percent on the basis of oxides, wherein 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.

A fiber optic imaging element includes medium-expansion and a fabrication method including: (1) matching a core glass rod with a cladding glass tube to perform mono fiber drawing; (2) arranging the mono fibers into a mono fiber bundle rod, and then drawing the mono fiber bundle rod into a multi fiber; (3) arranging the multi fiber into a multi fiber bundle rod, and then drawing the multi fiber bundle rod into a multi-multi fiber; (4) cutting the multi-multi fiber, and then arranging the multi-multi fiber into a fiber assembly buddle, then putting the fiber assembly buddle into a mold of heat press fusion process, and performing the heat press fusion process to prepare a block of the fiber optic imaging element with medium-expansion; and (5) edged rounding, cutting and slicing,

The multicomponent oxide glass has a composition including: 45-53 mol % SiO.sub.2; 22-30 mol % B.sub.2O.sub.3; 5-9 mol % Al.sub.2O.sub.3; 0.02-0.10 mol % Sb.sub.2O.sub.3; 0-18 mol % Li.sub.2O; 0-18 mol % Na.sub.2O; 0-18 mol % K.sub.2O; 0-13 mol % MgO; 0-13 mol % CaO; 0-13 mol % BaO; and 0-13 mol % ZnO. When the total content of Li.sub.2O, Na.sub.2O, and K.sub.2O is X mol % and the total content of MgO, CaO, BaO, and ZnO is Y mol %, 11≤X≤18 and 14≤X+Y≤24 hold, and the value of βOH calculated from βOH=α/t, where α represents a height of an absorption peak due to OH groups, observed in a range of 3400 cm.sup.−1 to 3800 cm.sup.−1 of an infrared absorption spectrum in no unit and t represents a thickness of the glass in cm, is 4 cm.sup.−1 or more.

Alkali-doped boroaluminosilicate glasses are provided. The glasses include the network formers SiO.sub.2, B.sub.2O.sub.3, and Al.sub.2O.sub.3. The glass may, in some embodiments, have a Young's modulus of less than about 65 GPa and/or a coefficient of thermal expansion of less than about 40×10.sup.−7/° C. The glass may be used as a cover glass for electronic devices, a color filter substrate, a thin film transistor substrate, or an outer clad layer for a glass laminate.

An optical material including: a silica host; and a Praseodymium dopant; wherein the Praseodymium atoms are configured to form nanoclusters in the silica host. In addition, the optical material may include an Ytterbium co-dopant. The nanoclusters include Ge, Te, Ta, Lu and/or F, Cl to minimize multi-phonon quenching. Moreover, the nanoclusters may be encapsulated in a low phonon energy shell to minimize energy transfer to the host matrix.

An optical fiber can include a core comprising silica co-doped with nitrogen and chlorine and an outer cladding surrounding the core. In some aspects, the core can be characterized by an annealing temperature of less than or equal to about 1150° C. and/or the core can include a relative refractive index Δ.sub.core in a range of from about 0.15% to about 0.45%.

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 fiber optic plate 122 including a plurality of core glasses 122a, a clad glass 122b covering the core glass 122a, and a light-absorbing glass 122c disposed between the plurality of core glasses 122a, wherein a content of TiO.sub.2 in the core glass 122a is 7% by mass or less, a content of B.sub.2O.sub.3 in the core glass 122a is 15% by mass or more, and a content of WO.sub.3 in the core glass 122a is more than 0% by mass.

Disclosed herein are glass compositions, articles made from the disclosed glass compositions, and methods of making the same. More specifically, disclosed herein is a glass composition comprising from about 10 to about 14 mol % of K.sub.2O; from 0 to about 4 mol % of CaO; from about 14 to about 18 mol % of Al.sub.2O.sub.3; and from about 66 to about 74 mol % SiO.sub.2.