Abstract: A method for fabricating silica glass is disclosed. The method includes the steps of (a) hydrolyzing silicon alkoxide; (b) hydrolyzing heterometal alkoxide containing Bi and Ti components; (c) mixing a solution containing hydrolyzed products of the silicon alkoxide and a solution containing hydrolyzed products of the heterometal alkoxide, thus forming a mixed solution; (d) molding gel by pouring the mixed solution into a forming mold; (e) drying the molded gel; and (e) performing heat-treatment of the dried gel so as to vitrify the gel.

Abstract: A porous optical fiber provided with air holes and a method for manufacturing the same are disclosed. The porous optical fiber includes a core having a first refractivity extended in a longitudinal direction, an external cladding layer having a second refractivity surrounding the core, and an internal cladding layer having a third refractivity formed between the core and the external cladding layer and provided with a plurality of air holes scattered therethrough.

Abstract: An apparatus for manufacturing a photonic crystal fiber preform having a plurality of holes that extend in a lengthwise direction of the photonic crystal fiber perform is disclosed. The apparatus includes a housing for receiving a raw material for the photonic crystal fiber perform, a first support section arranged at an upper part of the housing; a second support section arranged at a lower part of the housing, and a plurality of pins supported by the first and second support sections. At least a portion of each pin is positioned in the housing. The apparatus also includes a vacuum pump for vacuumizing the interior of the housing; a first pipe connected to the lower part of the housing to introduce the raw material into the housing; and a first valve installed on the first pipe to open and close the first pipe.

Abstract: A sol-gel process is disclosed. The process includes forming a sol by dispersing an organic binder and at least two kinds of fumed silica having different particle sizes into de-ionized water and forming a gel by injecting the dispersed sol into a mold.

Abstract: A sol-gel process is disclosed. The process includes the steps of creating a sol by dispersing an organic binder having Si—O backbone structure into de-ionized water together with fumed silica, injecting the dispersed sol into a mold to form a gel, drying the gel, removing organic substances remaining in the gel, removing impurities remaining in the gel and OH radicals, and heating the gel at a temperature to improve the consolidation of the gel.

Abstract: Disclosed is an apparatus for fabricating a preform used to manufacture a photonic crystal optical fiber having multiple holes extending in a longitudinal direction thereof. The apparatus includes a housing for containing a raw material for the photonic crystal optical fiber; a first support member positioned at one end of the housing; a second support member positioned at the other end of the housing; and multiple tubes respectively supported by the first and second support members to be at least partly located within the housing, wherein diameter of each multiple tube can be variable selectively depending on an amount of fluid poured through the open ends of the tubes.

Abstract: A method of fabricating a preform for a holey optical fiber, which prevents gel tubes from cracking includes the steps of: (a) forming sol using a starting material of silica glass; (b) pouring the silica glass in the sol state produced in step (a) into a plurality of molds, and gelating the silica glass to form a plurality of gel tubes, each having one air hole; (c) drying the gel tubes after removing the plurality of gel tubes from the individual molds; (d) applying a heat treatment of the gel tubes dried in step (c) to remove moisture and impurities contained in the gel tubes; (e) stacking the gel tubes, which have been subjected to heat treatment in step (d), in a predetermined array; and (f) sintering the stacked gel tubes, thereby vitrifying the gel tubes.

Abstract: Disclosed is a process for producing a holey fiber preform through a sol-gel molding method. The process comprises the steps of: (a) expanding a plurality of elongated tubes, wherein the tubes can be expanded/contracted by control of pressure in the tubes, (b) positioning the expanded tubes in the mold in a predetermined arrangement; (c) introducing a sol gel into the mold; (d) separating the gel from the mold, and contracting the tubes to form elongated air holes in the gel; and (e) removing the tubes. In the process, the tubes for forming air holes can be removed with no impact on the dried gel.

Abstract: A porous optical fiber provided with air holes and a method for manufacturing the same are disclosed. The porous optical fiber includes a core having a first refractivity extended in a longitudinal direction, an external cladding layer having a second refractivity surrounding the core, and an internal cladding layer having a third refractivity formed between the core and the external cladding layer and provided with a plurality of air holes scattered therethrough.

Abstract: A method for fabricating silica glass is disclosed. The method includes the steps of (a) hydrolyzing silicon alkoxide; (b) hydrolyzing heterometal alkoxide containing Bi and Ti components; (c) mixing a solution containing hydrolyzed products of the silicon alkoxide and a solution containing hydrolyzed products of the heterometal alkoxide, thus forming a mixed solution; (d) molding gel by pouring the mixed solution into a forming mold; (e) drying the molded gel; and (e) performing heat-treatment of the dried gel so as to vitrify the gel.

Abstract: Disclosed are fabrication method and device for a porous optical fiber preform. The fabrication method includes the steps of (a) rotating one or more rotating disks in a deposition furnace, wherein a plurality of shoot rods are coupled to the one or more rotating disks and spaced at predetermined intervals along a circumferential direction of the one or more rotating disks; (b) supplying a raw material in a gaseous state into the deposition furnace to deposit the raw material onto the shoot rods; (c) after the formation of a silica shoot by deposition of the raw material on the shoot rods, eliminating the shoot rods from silica shoot; and (d) sintering the silica shoot from which the shoot rods are eliminated.

Abstract: Disclosed is a colloidal silica composition and a method for producing high-purity silica glass using the same. The colloidal silica composition of the present invention comprise an alkoxysilane compound, an organic solvent, deionized water, and a basic catalyst. The colloidal silica composition further includes a basic organic material for adjusting a hydrogen ion concentration (pH) to prevent the formation of agglomerates when concentrated. Silica glass having high purity and excellent sinterability can be produced using the colloidal silica composition of the present invention.

Abstract: The present invention relates to a process of producing a silica glass in which the sol is transported from a mixer to a former under a certain amount of pressure. The transportation path of the sol is vacuumized in order to remove macro bubbles that can be potentially produced while the sol is transported from the mixer to the former. The interior of a piping connecting between the mixer for bearing the sol and the former for forming the gel is maintained in the vacuum state so as to effectively remove the macro bubbles, which can be potentially produced during the transportation of the sol.

Abstract: Disclosed are apparatus and method for ultrasonically dispersing a silica sol such as is used in a process of manufacturing a silica glass by a sol-gel method. The apparatus includes a sol feeder for holding a sol to be dispersed, a sol container for containing the ultrasonically dispersed sol, a medium tank having a liquid-phase ultrasonic medium, an ultrasonic vibrator for generating ultrasonic waves within the tank, and a sol pipe for providing a sol feeding path connecting the sol feeder and the sol container to each other, the sol pipe having a portion submerged under the ultrasonic medium in the medium tank. The portion of the sol pipe submerged under the ultrasonic medium has a shape bent in a zigzagged fashion.

Abstract: A fabrication method of graded index silica glass is disclosed. The method according to the present invention includes the steps of dispersing to form sol by mixing a starting material with a dispersion medium; molding the sol into a moisturized gel with a predetermined shape using a molding frame and separating the moisturized gel from the molding frame; drying the moisturized gel under a predetermined temperature and humidity level to remove the dispersion medium and to form a first dry gel having a predetermined moisture content distribution, hydrolyzing the moisture remained in the first dry gel and an additive solution by putting the first dry gel into the additive solution; re-drying the first dry gel, which underwent said hydrolysis, to form a second dry gel; and, thermal processing the second dry gel by supplying reaction gas thereto, removing impurities therefrom and annealing for isolation.

Abstract: A fabrication method of graded index silica glass is disclosed. The method according to the present invention includes the steps of dispersing to form sol by mixing a starting material with a dispersion medium; molding the sol into a moisturized gel with a predetermined shape using a molding frame and separating the moisturized gel from the molding frame; drying the moisturized gel under a predetermined temperature and humidity level to remove the dispersion medium and to form a first dry gel having a predetermined moisture content distribution, hydrolyzing the moisture remained in the first dry gel and an additive solution by putting the first dry gel into the additive solution; re-drying the first dry gel, which underwent said hydrolysis, to form a second dry gel; and, thermal processing the second dry gel by supplying reaction gas thereto, removing impurities therefrom and annealing for isolation.

Abstract: A method for producing a dopant doped high pure silica glass comprising the steps of: preparing powder by dispersing silica particles into a dispersion medium; adding a dopant containing gas; drying, heating and pulverizing the same in sequence to produce dopant doped silica powder; and, producing a dopant doped silica glass by using the silica powder produced by said powder preparing step as a starting substance.