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 of fabricating a nano composite material includes: forming an intermediate product by loading nano-sized reinforcing materials into an inside of a tube and arranging the nano-sized reinforcing materials in a linear direction; canning the intermediate material by inserting the intermediate material into an inside of a can and sealing the can; evacuating a gas contained in the can; melting the intermediate product in the can by heating the can; preheating a mold; and loading the can into the preheated mold and pressing the mold.

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: Disclosed is a method for manufacturing a preform for a photonic crystal fiber (PCF). The method includes the steps of (A) forming a dry gel having a cylindrical shape by forming a silica slurry obtained by mixing a monomer and a dimer and drying the slurry, and (B) forming air holes having the desired size and arrangement through the dry gel, thereby easily regulating the size and arrangement of the air holes and manufacturing various shapes of the preform.

Abstract: A method of fabricating a preform used for produce a holey fiber having air holes therein is disclosed. The method includes the steps of preparing a tubular mold having a plurality of pins for forming a plurality of air holes aligned in a predetermined pattern, injecting silica slurry including a monomer and a dimer into the tubular mold and forming silica slurry into a gel, demolding the gel from the pins and the tubular mold, and drying and sintering the gel formed with air holes. The size and alignment of the air holes are easily adjusted, thereby achieving a large preform without contamination preform during the fabricating process.

Abstract: The present invention discloses a method for fabricating silica glass using a sol-gel process, which includes a sol forming step for forming a sol by mixing a starting material, deionized water and an additive together; gelation step for gelatinizing the sol after filling a circular mold with the gel produced; gel drying step for separating the gel from the circular mold and drying the gel; setting step for placing the gel inside of a heat chamber and injecting helium gas into the heat chamber; and low heat treatment step for pressurizing and depressurizing an internal pressure of the heat chamber repeatedly for several times.

Abstract: Enclosed is an apparatus for analyzing micro-bubbles inside a high-purity glass tube by using a laser light dispersion. The apparatus includes: an optical base having a sample stage in a substantially horizontal orientation; a glass tube rotably mounted on the optical base in a substantially vertical orientation, the glass tube being rotated and translated in a vertical direction at a predetermined speed via the sample stage; a light generator disposed at one side of the glass tube for selectively irradiating a laser light onto an outer surface of the glass tube at a prefixed angle; and, a detector disposed at the other side of the glass tube for detecting the distribution and amount of micro-bubbles of the glass tube using the laser light passed through the glass tube.

Abstract: This invention discloses a method and an apparatus for sintering a gel tube formed by a sol-gel change. The sintering apparatus comprises a reaction chamber for accommodating the gel tube, sealed under a vacuum condition; a vacuum pump for adjusting the degree of vacuum inside the reaction chamber according to a control signal; a vacuum gauge for measuring the degree of vacuum inside the reaction chamber; a movable part for supporting the gel tube and for rotating and vertically moving the gel tube according to the control signal; a temperature sensor for measuring the temperature inside the reaction chamber; a heater for adjusting the temperature inside the reaction chamber according to the control signal so as to sinter the gel tube; and, a controller for controlling the vacuum pump, the heater, and the movable part for sintering the gel tube under the vacuum condition.

Abstract: A method for fabricating large aperture optical fiber preform using a sintering apparatus for gel tube, includes the steps of: forming a uniform sol by mixing/dispersing for mixing fumed silica with deionized water, and adding a dispersing additive to form uniform sol; injecting the sol into a mold with a certain tubular form, and then gellifying the sol; demolding the tube-shaped gel from the mold; drying the tube-shaped gel; processing (or Binder burn-out & Purification) organic compounds including remaining moisture, alkali metallic impurities, and hydroxides in the gel; inserting a primary preform into the tube-shaped gel and then fastening the preform; and after arranging the gel with the primary preform therein into a sintering apparatus, sintering/over cladding the gel with the primary preform therein under vacuum atmosphere at high temperature.

Abstract: Disclosed is a method for controlling a heat treatment in the process of fabricating a high purity silica glass via a sol-gel process using a low temperature heater having an inhalation line and an exhaust line. Accordingly, the method includes the steps of (a) identifying whether or not the diameter of the exhaust line is varied; (b) controlling the mass flow of the process gas according to the changed diameter of the exhaust line in step (a); (c) measuring an exhaust gas velocity discharged through the exhaust line; (d) comparing the exhaust gas velocity measured in the step (c) with the exhaust gas velocity after the scale of the exhaust line is varied; and, (e) repeating steps (b)-(d) if the comparison result in step (d) is different.

Abstract: Enclosed is an apparatus for analyzing micro-bubbles inside a high-purity glass tube by using a laser light dispersion. The apparatus includes: an optical base having a sample stage in a substantially horizontal orientation; a glass tube rotably mounted on the optical base in a substantially vertical orientation, the glass tube being rotated and translated in a vertical direction at a predetermined speed via the sample stage; a light generator disposed at one side of the glass tube for selectively irradiating a laser light onto an outer surface of the glass tube at a prefixed angle; and, a detector disposed at the other side of the glass tube for detecting the distribution and amount of micro-bubbles of the glass tube using the laser light passed through the glass tube.

Abstract: The present invention discloses a method for fabricating silica glass using a sol-gel process, which includes a sol forming step for forming a sol by mixing a starting material, deionized water and an additive together; gelation step for gelatinizing the sol after filling a circular mold with the gel produced; gel drying step for separating the gel from the circular mold and drying the gel; setting step for placing the gel inside of a heat chamber and injecting helium gas into the heat chamber; and low heat treatment step for pressurizing and depressurizing an internal pressure of the heat chamber repeatedly for several times.

Abstract: A silica product, method and apparatus for manufacturing a tube-shaped silica glass product using a molded green body having a hollow rod structure. A molded green body having a hollow rod structure has a uniform outer diameter and has a bore having an inner diameter increasing gradually from one end to the other. When sintered in a vertically movable sintering furnace, a tube-shaped silica glass product having a longitudinal cross section distribution less than a tolerance limit may be obtained. Optical fiber manufactured using the silica glass tube according to the present invention may have a uniform longitudinal geometrical structure, thereby exhibiting superior transmission characteristics.

Abstract: Disclosed is an apparatus and method for sintering an over-jacketing tube in the zone sintering phase of an optical fiber preform fabrication process using a sol-gel process. The sintering apparatus includes: a processing tube; a gel tube assembly connected to a top rotation cap positioned at the top opening of the processing tube and being rotated at a predetermined rate, a ceramic pin extending downwardly from the center axis of the rotation cap, and a gel tube suspended from the bottom of the ceramic pin and suspended along the same axle of the processing tube; and a movable furnace initially positioned at the bottom of the processing tube and translating in a vertical direction along the processing tube for thermally treating the gel tube.

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 method of a fabricating silica glass by sol-gel process is provided. The method includes mixing silica, a binder, a dispersing agent and a gelling agent, and forming a sol without air bubbles; injecting the sol into a mold, the injection of the sol into the mold being controlled by the pressure of an inert gas; gelating the sol injected into the mold and demolding the gel; and drying the demolded gel, and thermally-treating the dried gel. Therefore, incorporation of impurities and air bubbles during injection of a sol into a mold is minimized, and injection amount and injection rate of the sol can be controlled.

Abstract: A method of a fabricating silica glass by sol-gel process is provided. The method includes mixing silica, a binder, a dispersing agent and a gelling agent, and forming a sol without air bubbles; injecting the sol into a mold, the injection of the sol into the mold being controlled by the pressure of an inert gas; gelating the sol injected into the mold and demolding the gel; and drying the demolded gel, and thermally-treating the dried gel. Therefore, incorporation of impurities and air bubbles during injection of a sol into a mold is minimized, and injection amount and injection rate of the sol can be controlled.

Abstract: A silica glass composition having silica and a binder is provided. The binder is methylcellulose or a polymer comprising repeating units represented by the formula (1): (—CH2—CH(OR)—)  (1) where R is a C1-C12 alkyl group or is the acetyl group. The silica glass composition according to the present invention includes a binder cheaper than the conventional polyethyloxazoline and is not hazardous to humans. The air bubbles removing efficiency can be enhanced by reducing the viscosity of the sol, and the content of solid in the sol can be increased by using the silica glass composition according to the present invention. Also, the strength of the wet gel is increased allowing the gel to be easily handled in a subsequent process. The silica glass composition according to the present invention can be used in manufacturing silica glass for a semiconductor device and an optical lens as well as a tube for optical fiber.