Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

A method for performance prediction of a functional glass system, which includes the following steps: determining species of atoms for structural search according to components of a target glass system; performing structural search based on a first principle to search out compounds that can be formed by interaction between the atoms; comparing a formation energy and a phonon spectrum of each of the compounds to obtain stable compounds; constructing a glass structural composition diagram according to the stable compounds, microstructural units of a glassy compound adjacent to a target glass composition point are structural genes of the glass; and calculating a property of the target glass according to a leverage model formula of a multiplex glass system, the leverage model formula of the multiplex glass system being P0=Σ.sub.i=1.sup.nPi×Li.

A method for performance prediction of a functional glass system, which includes the following steps: determining species of atoms for structural search according to components of a target glass system; performing structural search based on a first principle to search out compounds that can be formed by interaction between the atoms; comparing a formation energy and a phonon spectrum of each of the compounds to obtain stable compounds; constructing a glass structural composition diagram according to the stable compounds, microstructural units of a glassy compound adjacent to a target glass composition point are structural genes of the glass; and calculating a property of the target glass according to a leverage model formula of a multiplex glass system, the leverage model formula of the multiplex glass system being P0=Σ.sub.i=1.sup.nPi×Li.

Provided is a thermally stable and inexpensive infrared-transmitting glass. An infrared-transmitting glass contains, in terms of % by mole, over 0 to 9% Ge, over 0 to 50% Ga, 50 to 90% Te, 0 to 40% Si+Al+Ti+Cu+In+Sn+Bi+Cr+Sb+Zn+Mn+Cs+Ag+As+Pb, and 0 to 40% F+Cl+Br+I.

Provided is a thermally stable and inexpensive infrared-transmitting glass. An infrared-transmitting glass contains, in terms of % by mole, over 0 to 9% Ge, over 0 to 50% Ga, 50 to 90% Te, 0 to 40% Si+Al+Ti+Cu+In+Sn+Bi+Cr+Sb+Zn+Mn+Cs+Ag+As+Pb, and 0 to 40% F+Cl+Br+I.

Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

Provided is optical glass containing, in terms of mol % of cations: 10 to 60% of a La.sup.3+ component; more than 0% and up to 75% of a Ga.sup.3+ component; and 5 to 75% of a Nb.sup.5+ component, in which a total amount of the La.sup.3+ component, Ga.sup.3+ component, and Nb.sup.5+ component is 60 to 100%.

The invention relates to a process for inscribing a three-dimensional structure formed from variations in refractive index in the bulk of a transparent oxide glass comprising silver ions by femtosecond-laser-beam irradiation, the method comprising: generating a laser beam made up of a series of ultra-brief light pulses of pulse duration shorter than the characteristic time of thermalization of the glass so as to achieve an excitation at the point of irradiation via multi-photon interaction; focusing said beam at a desired depth in the glass; irradiating point by point the glass with said beam so as to form the structure in the glass along a predetermined path, the number of pulses, the repetition rate of the pulses and the irradiance at each irradiation point being controlled to induce an accumulation of silver aggregates localised in an annular peripheral region around an irradiation point, said accumulation of aggregates generating a variation in refractive index in the annular peripheral region around the irradiation point, and to erase a variation in refractive index in a segment of an annular peripheral region generated around another irradiation point when said segment of the peripheral region coincides with a region of the laser beam.

Glass compositions include phosphorus oxide (P.sub.2O.sub.5), niobia (Nb.sub.2O.sub.5), barium oxide (BaO) and potassium oxide (K.sub.2O) as essential components and may optionally include titania (TiO.sub.2), calcium oxide (CaO), sodium oxide (Na.sub.2O), lithium oxide (Li.sub.2O), bismuth oxide (Bi.sub.2O.sub.3), strontium oxide (SrO), tungsten oxide (WO.sub.3) and other components. The glasses may be characterized by high refractive index at 587.56 nm at comparably low density at room temperature.

Glass compositions include phosphorus oxide (P.sub.2O.sub.5), niobia (Nb.sub.2O.sub.5), barium oxide (BaO) and potassium oxide (K.sub.2O) as essential components and may optionally include titania (TiO.sub.2), calcium oxide (CaO), sodium oxide (Na.sub.2O), lithium oxide (Li.sub.2O), bismuth oxide (Bi.sub.2O.sub.3), strontium oxide (SrO), tungsten oxide (WO.sub.3) and other components. The glasses may be characterized by high refractive index at 587.56 nm at comparably low density at room temperature.