Abstract: To provide a manufacturing method with which lithium difluorophosphate powder can be recovered from a lithium difluorophosphate solution. A method for manufacturing lithium difluorophosphate powder is used which includes the steps of precipitating solid lithium difluorophosphate by adding a poor solvent to a solution in which lithium difluorophosphate is dissolved in a main solvent, and obtaining lithium difluorophosphate powder by solid-liquid separation of the solid lithium difluorophosphate from the liquid containing the main solvent and the poor solvent, wherein the relational expression between the octanol/water partition coefficient PP of the main solvent and the octanol/water partition coefficient PA of the poor solvent is defined by the following formula (1). PA??4/3×PP+1.

Abstract: To provide a manufacturing method with which lithium difluorophosphate powder can be recovered from a lithium difluorophosphate solution. A method for manufacturing lithium difluorophosphate powder is used which includes the steps of precipitating solid lithium difluorophosphate by adding a poor solvent to a solution in which lithium difluorophosphate is dissolved in a main solvent, and obtaining lithium difluorophosphate powder by solid-liquid separation of the solid lithium difluorophosphate from the liquid containing the main solvent and the poor solvent, wherein the relational expression between the octanol/water partition coefficient PP of the main solvent and the octanol/water partition coefficient PA of the poor solvent is defined by the following formula (1). (1): PA??4/3×PP+1.

Abstract: Provided are a method for judging the amount of impurities in a solvent for an electrolyte liquid to be used in a non-aqueous electrolyte liquid battery, that enables judging, more easily than conventionally, the amount in which several types of impurities causing degradation of battery performance is contained in the solvent; a method for producing an electrolyte liquid using this judging method; and an electrolyte liquid. The judging method includes: obtaining a reaction solution by adding a Lewis acid to the solvent; measuring the Hazen value of the reaction solution; and judging whether the value is no more than a predetermined threshold. The producing method includes mixing, with an electrolytic salt, the solvent for which the Hazen value has been judged to be no more than the threshold by the judging method. The electrolyte liquid contains: the solvent with the Hazen value as judged above; and an electrolytic salt.

Abstract: A glass includes (a) a matrix containing a compound of at least one nonmetallic element; and (b) a particle selectively formed in the matrix. This particle is made of the at least one nonmetallic element. A process for producing such glass includes (a) providing a blank glass containing a compound of at least one nonmetallic element; (b) condensing a pulsed laser beam to a focal point in the blank glass such that a particle is selectively formed in the blank glass at a position corresponding to the focal point, the particle being made of the at least one nonmetallic element dissociated from the compound; and (c) moving the focal point in the blank glass to produce a pattern of the particle. The glass is suitable for optical functional elements.

Abstract: Pulsed light is irradiated to an amorphous base material, to produce therein one or more single crystals or polycrystals having nonlinear characteristic advantageous for light communication and laser technique. An external field such as electric field or magnetic field may be applied to the amorphous material, or a seed crystal or crystalline substrate may be used to promote crystallization from a contact interface between the amorphous material and the seed crystal or crystalline substrate.

Abstract: The invention relates to a 1.4-1.52 &mgr;m-band optical amplifier. This optical amplifier includes (a) a first pumping source for a first pumping light in a wavelength range defined as being not less than 0.65 &mgr;m and being less than 0.77 &mgr;m; (b) a second pumping source for a second pumping light in a wavelength range of from 1.0 to 1.2 &mgr;m; (c) an optical multiplexer for combining said first and second pumping lights with a signal light, to produce a combined light; and (d) a light amplifying optical waveguide for amplifying said signal light by receiving said combined light, said optical waveguide comprising a core doped with Tm. The optical amplifier is highly efficient.

Abstract: A glass includes (a) a matrix containing a compound of at least one nonmetallic element; and (b) a particle selectively formed in the matrix. This particle is made of the at least one nonmetallic element. A process for producing such glass includes (a) providing a blank glass containing a compound of at least one nonmetallic element; (b) condensing a pulsed laser beam to a focal point in the blank glass such that a particle is selectively formed in the blank glass at a position corresponding to the focal point, the particle being made of the at least one nonmetallic element dissociated from the compound; and (c) moving the focal point in the blank glass to produce a pattern of the particle. The glass is suitable for optical functional elements.

Abstract: Pulsed light is irradiated to an amorphous base material, to produce therein one or more single crystals or polycrystals having nonlinear characteristic advantageous for light communication and laser technique. An external field such as electric field or magnetic field may be applied to the amorphous material, or a seed crystal or crystalline substrate may be used to promote crystallization from a contact interface between the amorphous material and the seed crystal or crystalline substrate.

Abstract: Pulsed light is irradiated to an amorphous base material, to produce therein one or more single crystals or polycrystals having nonlinear characteristic advantageous for light communication and laser technique. An external field such as electric field or magnetic field may be applied to the amorphous material, or a seed crystal or crystalline substrate may be used to promote crystallization from a contact interface between the amorphous material and the seed crystal or crystalline substrate.

Abstract: The invention relates to an optical waveguide having a core made of one member selected from halide glasses, chalcogenide glasses and oxyhalide glasses. This one member is doped with both of erbium and cerium. The invention further relates to a 1.5 &mgr;m-band optical amplifier having the optical waveguide for amplifying the light. Due to the doping of both erbium and cerium, it becomes possible to provide a highly efficient optical amplifier having low noise and wide band. With this, it becomes possible to construct an optical communication network having high credibility, high capacity and high speed.

Abstract: An upconversion laser material includes a micro-sphere which is doped with an ion of a rare earth element and made of one selected from the group consisting of crystals and glasses. Thus, the micro-sphere achieves the light confinement therein and serves as a resonator. Therefore, the Q-value of the resonator becomes large. With this, it is possible to obtain the upconversion laser oscillation at room temperature.

Abstract: An optical fiber preform includes a core made from a fluoride glass which is doped with a rare earth, and a cladding surrounding the core. The cladding is made from one of an oxide glass and a fluoroxide glass. The core has a characteristic of amplification at 1.3 .mu.m-band. The cladding does not have absorption at 1.3 .mu.m-band. The preform is useful as a material for a fiber optical amplifier in optical communication systems.

Abstract: A method of forming a fiber glass preform includes the steps of: (a) pouring a cladding glass into a mold; (b) pouring a core glass on a flat horizontal upper surface of the cladding glass so as to form a united glass body having the core glass and the cladding glass under a condition that viscosity of the cladding glass and viscosity of the core glass are adjusted to certain predetermined values respectively so that the core glass is separated from and placed on the cladding glass; (c) cooling the united glass body to solidify the same so that the cladding glass is deformed by contraction thereof so as to produce a depression at a top middle portion thereof and that the core glass is deformed so as to form a projected portion thereof to fill the depression therewith; (d) separating the united glass body into an upper portion and a lower portion comprising the projected portion of the core glass; and (e) extruding the lower portion of the united glass body so as to form the fiber glass preform.