Abstract: An optical waveguide substrate, which has less particles or concave pits caused by Oxidation Induced Stacking Fault on the quartz film when oxidizing the surface of the silicon substrate relatively thickly and forming on its surface a quartz film to become an optical waveguide, is manufactured. The making method of the optical waveguide substrate comprises a step of exposing a silicon substrate to an atmosphere of oxidizing gas while heating to form a quartz film on the surface thereof for an optical waveguide, characterized in that a density of Oxygen contained in said silicon substrate is 24 ppma at maximum.

Abstract: In a process for producing an optical fiber preform, a starting member and a glass synthesizing burner are reciprocated relative to each other so that fine glass particles synthesized with the burner are deposited layer by layer on the starting member, and a heating power of the glass synthesizing burner in a nonsteady outside diameter portion at either end of the soot preform is adjusted to control the temperature of the nonsteady outside diameter portion at either end against local elevation. The starting member is formed of a transparent glass rod that is held within a vessel and rotatable about its own axis, the burner is fitted on a lateral side of the vessel at right angles to the rotating axis of the starting member and is movable towards or away from the starting member.

Abstract: In a known process for the manufacture of an elongated porous SiO2 preform, SiO2 particles are deposited on the mantle surface of a cylindrical carrier rotating about its longitudinal axis. The SiO2 particles are formed by means of a plurality of deposition burners which are arranged, at a distance from one another, in at least one burner row extending parallel to the longitudinal axis of the carrier. The burners are moved in a repeated cycle back and forth along the forming preform and between turnaround points where the direction of their motion is reversed. Measures are taken in the process to prevent or reduce overheating of the preform in the turnaround point regions. These measures can lead to variations in the rate of deposition.

Abstract: A processing method of a silica glass fiber, which is applicable to a long fiber, to improve its UV resistance by UV irradiation and heat treatment. Initially, a heating furnace 1 is positioned such that the left end of the silica glass fiber is within the heating furnace 1. Then, the heating furnace 1 is moved toward the right, while UV is irradiated with a UV source to the left end surface of the silica glass fiber. Since the silica glass becomes transparent due to removal of structural defects that have been caused by the UV irradiation, the UV travels further forward and causes other structural defects there. When the heating furnace 1 is moved there, the structural defects are removed and the silica glass fiber becomes transparent. By repeating these steps, the fiber is processed throughout length. Thus, mass production becomes possible and an improvement of productivity and lower costs can be achieved.

Abstract: A silicon surface oxidation device utilizes a steam generator in which heated water is barely in contact with the members of the device, steam with no contamination is efficiently generated, and the silicon surface can be oxidized through relatively large thickness by using a steam oxidation method which is simple and high in safety. The steam generator has a feed port for pure water which flows along a surface in a chamber, an oscillator for oscillating a microwave toward the surface, a steam exit port for sending out the steam of the pure water generated from the surface by the microwave, and a discharge port for the pure water flowing along the surface. A heating furnace is connected to the steam exit port, and silicon placed in the heating furnace is oxidized by the steam generated by the microwave.

Abstract: A method of cooling an optical fiber while it is being drawn through contact with at least one cooling fluid in at least one cooling area, wherein said method is such that fast cooling, i.e. cooling that is faster than cooling in the surrounding air, is followed by slow cooling, i.e. cooling slower than cooling in the surrounding air, the temperature of the fiber in an intermediate area between the two cooling areas lying in the range 1200° C. to 1700° C. in the case of silica glass fibers.

Abstract: A fiber draw furnace for drawing a fiber from a preform has a thermographic sensor in combination with a thermographic profiling processor. The thermographic sensor responds to infrared energy radiating from the fiber, for providing a thermographic sensor signal containing information about the infrared energy radiating from the fiber. The thermographic profiling processor responds to the thermographic sensor signal, for providing a thermographic profiling processor signal containing information about a thermographic profile of variations in the heat emitted across the width or along the length of the fiber. The fiber is typically quartz glass. The thermographic sensor includes an infrared filter and lens combination for filtering out infrared energy outside a range of 8-12 microns radiating from the quartz fiber. The thermographic sensor includes a lens and an infrared sensor for focusing and sensing infrared energy inside a range of 8-12 microns radiating from the quartz fiber.

Abstract: A method for drawing a glass ingot comprises holding a vertically suspended glass ingot 5 at an upper end thereof, passing the ingot through a heating furnace 10 having upper and lower openings, and drawing the glass ingot while moving one end or both ends thereof, wherein a plurality of heating means 1 are provided along vertical directions in the heating furnace 10, and the temperatures of the respective heating means 1 are individually control to control a temperature distribution within the heating furnace 10.

Abstract: The specification describes a process and apparatus for collapsing preform tubes in Modified Chemical Vapor Deposition processes. The problem of bubble formation during tube collapse was found to be attributable to excess dopant vapor pressure emitted from the hot zone during the final stage of tube collapse. This excess pressure is controlled by cooling the tube in advance of the torch, thereby decreasing the viscosity of the dopant vapor and increasing its transport rate. This is found to reduce internal tube pressure and eliminate bubble formation in the collapsed preform.

Abstract: In the fiber-drawing method, a first preform is lowered along a fiber-drawing axis through a fiber-drawing oven so as to be heated and drawn down into an optical fiber, and a second preform is lowered along the fiber-drawing axis through the fiber-drawing oven so as to be heated and drawn down in turn after the first preform has been withdrawn. While the first preform is being drawn down into a fiber, the second preform is heated in a preheating oven disposed adjacent to the fiber-drawing oven so as to raise the second preform to a temperature which is slightly below the fiber-drawing temperature, and the preheated second preform is transferred quickly onto the fiber-drawing axis after the first preform has been withdrawn therefrom. This method contributes to increasing the capacity for producing optical fibers.

Abstract: A supplemental controller for a fiber glass bushing actively performs heating and cooling of a connected segment of the bushing which is otherwise controlled by a primary controller. In one embodiment, the supplemental controller performs heating by means of current injection into a connected bushing segment and cooling by means of current diversion from or around the connected bushing segment. Initial start-up and balancing operations can be performed without activation of the supplemental controller. In another embodiment of the invention, the supplemental controller heats a bushing segment by injecting current in-phase with current from the primary bushing controller and cools the bushing segment by injecting current out-of-phase with current from the primary bushing controller.

Abstract: An apparatus and method used in manufacturing a long period grating filter are provided. The apparatus used in manufacturing a long period grating filter includes an upper body including a plurality of teeth spaced from each other by a predetermined distance and a lower body having teeth spaced from each other by the same distance as the teeth of the upper body and a plurality of grooves in a direction perpendicular to the teeth in which an optical fiber is loaded, wherein the upper and lower bodies are engaged with each other, and a plurality of grooves are formed in the loaded optical fiber by abrading the loaded optical fiber by moving the upper body in a direction parallel to the teeth. According to the present invention, an excimer laser, various other expensive equipment, and an optical fiber sensitive to ultraviolet rays are not required for manufacturing the long period grating filter. Accordingly, complicated hydrogen processing is not necessary.

Abstract: A supplemental controller for a fiber glass bushing actively performs heating and cooling of a connected segment of the bushing which is otherwise controlled by a primary controller. In one embodiment, the supplemental controller performs heating by means of current injection into a connected bushing segment and cooling by means of current diversion from or around the connected bushing segment. Initial start-up and balancing operations can be performed without activation of the supplemental controller. In another embodiment of the invention, the supplemental controller heats a bushing segment by injecting current in-phase with current from the primary bushing controller and cools the bushing segment by injecting current out-of-phase with current from the primary bushing controller.

Abstract: A method for drawing a glass ingot into a rod having a given outer diameter is described. The method is characterized in that when the glass ingot is fed into a heating zone at a final tapered portion thereof, a temperature in the heating zone is decreased so that the final tapered portion is prevented from being drawn in excess owing to the heat from the heating zone.

Abstract: Bubble-free core glass can be deposited at relatively high rate (e.g., >0.3 gm SiO.sub.2 /minute, preferably 0.6 gm SiO.sub.2 /minute or more) by MCVD if the deposition conditions are appropriately selected. For instance, a relatively high torch traverse speed, a relatively low sintering temperature, and/or relatively low gas flow rates can facilitate high rate deposition of bubble-free glass. By way of example, conditions are disclosed that yielded essentially bubble-free core glass (.DELTA.=0.35%) at a rate of 1 gm SiO.sub.2 /minute.

Abstract: The transmission properties of an optical fiber are enhanced by cooling the fiber gradually to temperatures of at least -300.degree. Fahrenheit, maintaining the fiber at such reduced temperature for a time suitable to stabilize the transmission properties of the fiber, and then allowing the fiber gradually to return to normal room temperature. The heating of the fiber to restore it to room temperature in part is accomplished by transmitting through the fiber optical pulses of the frequency and repetition rate the fiber will experience in normal use.

Abstract: In a known process for the production of quartz glass bodies, SiO.sub.2 particles are deposited of the mantle surface of a cylindrical carrier rotating about its longitudinal axis, forming an elongated, porous preform, where the SiO.sub.2 particles are formed in a plurality of flame hydrolysis burners which are arranged in at least one burner row parallel to the longitudinal axis of the carrier and are moved at a preset translational speed forward and back between turnaround points at which points their direction of movement is reversed, and in which process the preform is sintered. In order to make available on this basis an easily accomplished process that makes it possible to manufacture a preform which is largely free of localized density variations, the invention proposes on the one hand that the base value of the surface temperature of the preform being formed be kept in a range between 1,050.degree. C. and 1,350.degree. C.

Abstract: A method for coating an optical fiber (1) has the optical fiber (1) exiting the longitudinal direction through a coating nozzle (10) from a volume (11) which is filled with a liquid hardenable coating material (6). The surface of the fiber is spaced from the wall (12) of the coating nozzle (10). The viscosity of the coating material (6) at room temperature is greater than 2500 mPa.multidot.s and the temperature of the coating material (6) is adjusted high enough for the coating material (6) to have a viscosity of less than 2000 mPa.multidot.s.

Abstract: A method for manufacturing quartz glass in a flame hydrolysis reaction inside a furnace, including the steps of mixing a gas containing Si, a combustion-supporting gas, and a combustible gas and discharging this mixed gas from a burner; producing a quartz glass powder by causing the mixed and discharged gases to react in a flame within the furnace while an opening area of an opening and shutting system of the furnace is controlled; and producing a quartz glass ingot by depositing and vitrifying the quartz glass powder on a target surface facing an interior of the furnace, wherein said producing step includes the step of controlling the opening area of the opening and shutting system of the furnace in accordance with the amount of growth of the ingot on the target surface.

Abstract: Disclosed is a method of controlling the diameter of a glass rod drawn from a glass preform. The diameter control begins as soon as a glass gob begins to move away from a heated portion of the preform. The velocity of the gob is measured and furnace temperature adjusted to maintain gob velocity at a pre-selected target value. By starting diameter control at this early stage of the process, utilization of the preform is improved as is the utilization of the drawing equipment.

Abstract: A method of fabricating an optical fiber doped with a rare earth component using a volatile complex, which flattens the light frequency response under a stimulated emission of radiation principle using a modified chemical vapor deposition method. Silicon tetrachloride (SiCl.sub.4) and oxygen are injected into a quartz reaction tube under a heating process, so that a cladding layer is repeatedly deposited. Then, a volatile organic metal chelate, silicon tetrachloride and oxygen are injected into the quartz reaction tube, and then heated and water-cooled to form a porous layer. At the same time, a rare earth element is deposited on the porous layer, to thereby form a core layer. Thereafter, via a high heating process, a preform is completed. Then, an optical fiber is obtained from the preform via a drawing-out process. Here, hydroxide ions (OH.sup.

Abstract: A method of drawing an optical fiber preform to manufacture an optical fiber, includes the steps of heating an optical fiber preform to temperatures at which the heated preform can be drawn, drawing the heated optical fiber preform by applying tension to the preform, and making the tension substantially constant during the drawing step. The particular method permits manufacturing an optical fiber exhibiting uniform transmitting characteristics, particularly uniform transmission loss, over the entire lengthwise region of the optical fiber, even if the optical fiber is manufactured by drawing an optical fiber preform having a large diameter.

Abstract: In accordance with the invention, the index of refraction of a region of a glass body is selectively increased by treating the glass with hydrogen or deuterium, heating the hydrogenated glass to a temperature in excess of 500.degree. C., permitting the glass to rapidly cool below 100.degree. C. and exposing the region to UV radiation, preferably in the range 300 nm to 400 nm. The result is an increase in the refractive index of the irradiated region. Absorption is via a GODC band at 330 nm believed to result from a singlet to triplet transition. This band is about 1000 times weaker than the commonly used band at 240 nm. This process can be used to make and adjust a variety of optical waveguide devices such as photoinduced Bragg gratings and long period gratings.

Abstract: In a drawing method and drawing apparatus according to the present invention, a forward end portion of an optical fiber glass preform is heated and melted while the glass preform is fed into a drawing furnace 3 so that an optical fiber is drawn, and the optical fiber glass preform is heated in a position just above the drawing furnace to make the surface of the glass preform clean.

Abstract: A vertically disposed apparatus used to make core-clad optical fibers inces an inner elongated cylinder removably closed at the top and provided at the bottom with an inner exit port of a smaller diameter than the inner cylinder and an outer cylinder, disposed around the inner cylinder, removably closed at the top and provided at the bottom with an outer exit port of a smaller diameter than the outer cylinder. The inner exit port is of a smaller diameter than the outer exit port and is disposed directly above the outer exit port. The apparatus also includes a heater for heating the inner and outer cylinders and acces to the inner and the outer cylinders for individually pressurizing inner and outer cylinders.

Abstract: A method for side writing Bragg gratings, having minimal birefringence, in a waveguide structure is disclosed. The method employs the orientation of the polarization direction of the writing light beam relative to the long axis of the waveguide structure together with the orientation of the intrinsic birefringence slow axis to effectively minimize birefringence in the subject grating.

Abstract: During the fire-polishing of a lengthwise extended glass body (3), for example a preform for drawing optical fibers, the glass body (3) is held by a holding device (5, 7), and is heated by a burner (23) moving at a variable advancing speed parallel to the lengthwise axis (19). The surface temperature of the glass body (3) is determined with a temperature measuring device (25). The mechanical stress condition of the glass body (3) is detected with an optical device (29) and can be controlled by varying the burner temperature and/or the advancing speed of the burner. The invention makes it possible to counteract the occurrence of high mechanical stresses in the glass body (3).

Abstract: A method of making core holes in cast cladding glass for fabricating optical fiber preforms to make single and multimode optical fibers. Liquid cladding glass is pored into a casting mold having a metallic wire that is translated through the liquid glass as it cools so that the wire essentially carves out a smooth cylindrical core hole along the cylindrical axis of the cooled cladding glass. The method substantially reduces surface contamination at the interface of the core hole and the cladding glass because any liquid glass that comes in contacts with the metallic wire is removed during the process, leaving behind a pristine glass surface.

Abstract: A system and method for providing an optical coupler is disclosed. The system and method comprise providing a plurality of optical fibers formed together in parallel and providing a torch capable of maintaining a temperature of approximately 1200 degrees Celsius, plus or minus approximately 50 degrees Celsius on the plurality of optical fibers, for a predetermined time. An optical coupler made in accordance with the method and system possesses improved uniformity and insertion loss.

Abstract: A supplemental controller for a fiber glass bushing actively performs heating and cooling of a connected segment of the bushing which is otherwise controlled by a primary controller. In one embodiment, the supplemental controller performs heating by means of current injection into a connected bushing segment and cooling by means of current diversion from or around the connected bushing segment. Initial start-up and balancing operations can be performed without activation of the supplemental controller. In another embodiment of the invention, the supplemental controller heats a bushing segment by injecting current in-phase with current from the primary bushing controller and cools the bushing segment by injecting current out-of-phase with current from the primary bushing controller.

Abstract: A method of fabricating optical preforms that yield optical fibers having minimal scattering centers by substantially eliminating bubbles and crystallites that form during preform fabrication. The method utilizes glasses having low viscosity in their liquid state to eliminate large bubbles that contain ambient gasses. Small bubbles that have sizes comparable to the wavelength of light are eliminated by simultaneously vacuum-pumping and slow-cooling the liquid glass used to fabricate the preform before pouring the glass into the preform cast mold. Finally, bubbles due to the formation of vacuums in the preform are eliminated by applying a temperature gradient across the cast mold to induce a steep vertical gradient in viscosity in the liquid glass when the liquid glass is poured in the mold.

Abstract: A vaporizer (film evaporator) (13) for halide-free, silicon-containing liquid reactants used in producing preforms is provided. The vaporizer includes a plurality of packed-bed columns (22) surrounding a central tube (24). A mixture of liquid reactant, e.g., octamethylcyclotetrasiloxane, and gas, e.g., oxygen, is sprayed onto the top surfaces (54) of the columns (22) by a set of spray nozzles (32). The liquid reactant and the gas flow downward together through the columns and are heated by hot oil (28) which flows around the columns' walls (50). The liquid reactant evaporates into the gas until the dew point temperature is reached, at which point all of the liquid reactant will have been converted into vapor. The vapor/gas mixture exits the bottom surfaces 56 of columns (22), where its direction of flow changes from downward to upward. This change in flow direction separates higher molecular weight species (46) from the vapor/gas mixture.

Abstract: In order to provide an improved process for the production of a glass preform for an optical fiber which includes substantially no bubble formation therein and also has a substantially uniform shape, the present invention provides a process for the production of a glass preform which is at least partially formed from silica. In particular, a body is formed on a rod by depositing fine glass particles thereon, preferably by the vapor phase reactions, and heating the body to vitrify under a reduced atmosphere or a vacuumed atmosphere so that the glass preform is produced.

Abstract: This process for producing an optical waveguide comprises a step of sintering a glass fine-particle layer to form a upper cladding layer, and a step of controlling a refractive index of the upper cladding layer by changing a temperature decreasing rate when the glass layer is cooled down to the room temperature.

Abstract: An optical fiber glass preform is preheated so that it is uniformly preheated therethrough, then a surface of the preform is abraded by an oxyhydrogen flame to obtain a smooth optical fiber glass preform. This method is advantageous when relatively larger diameter preforms are treated in this manner because the step of uniformly preheating the preform reduces or eliminates a temperature differential therein. The temperature differential could otherwise cause the preform to crack during cooling.

Abstract: A method for producing an oxide glass thin film is provided, in which volatilization of additives in a porous film from which the thin film is formed is effectively suppressed, and which the oxide glass film has a desired arrangement of refractive index with a low optical loss. According to this method, glass fine particles mainly containing SiO.sub.2 with a first additive are deposited on a substrate to form a porous thin film. A gas containing a second additive is supplied to a first chamber and heated to a first predetermined temperature profile to provide a heated gas containing an oxide. After disposing the substrate in a second chamber communicated with the first chamber, the substrate is heated to make the deposited porous glass into transparent glass while controlling a temperature in the second chamber according to a second temperature profile.

Abstract: The invention relates to a method of drying and sintering porous optical fiber preforms, especially those consisting of a solid glass core cane surrounded by a layer of cladding soot. After it is dried in a dehydrating atmosphere, the porous preform is heated to a presinter temperature just below that at which it would begin to rapidly densify. The various temperature holds and ramp rates are such that the preform is consolidated in a relatively short time without becoming cloudy or exhibiting other defects that would adversely affect the optical fiber drawn from the consolidated draw blank.

Abstract: The present invention provides a method for manufacturing an optical fiber coupler in which an optical fiber is elongated and heated by using a heating source under a constant tension. The heat source is controlled based on the ratio of a target elongating speed and an actual elongating speed of the optical fiber.

Abstract: Disclosed is an improved device and method for detecting fiber breakouts and fiber restarts in processes or systems for making fibers from a molten thermoplastic material. In these processes the running fibers induce ambient air into the array of hot fibers close to the nozzles where the fibers are formed, but this air flow essentially ceases when the fiber breaks out. A thermocouple junction located in the path of this airflow will sense temperature changes caused by fiber breakouts and fiber starts. The present invention simplifies and increases the accuracy of prior art sensor systems by eliminating hardware holding this thermocouple and instead uses one or more small holes in a bushing frame plus the refractory used to hold the fiberizing bushing in the frame to hold the thermocouple in the appropriate place.

Abstract: In accordance with the invention a planar waveguide device is fabricated by providing a substrate with an undercladding, depositing a particulate layer of core glass on the undercladding, consolidating the particulate layer by low temperature viscous sintering, patterning the consolidated layer to form an optical waveguide and applying an overcladding. The glass layers can be deposited quickly and economically by slurry dipping, centrifuging or electrophoresis. In a preferred embodiment the substrate is silicon, and the core glass is sodium-boro-silicate.

Abstract: A method for applying a carbon coating to an optical fiber wherein the build up of reaction by-products within the reactor is reduced by providing cooler reactors walls, dual fiber exit ports with different inside diameters, and gas shielding at one fiber exit port.

Abstract: Sol-gel processing of a silica glass body is facilitated by rapid drying. The body, having been heated to a temperature of about 200.degree. C. in a hermetically sealed vessel, is vented while reducing temperature. Termination of drying coincides with reduction to atmospheric pressure.

Abstract: Heating a wet colloidal gel body in an autoclave above its 1-atmosphere boiling point, under rigorously defined conditions, avoids shrinkage during subsequent drying. As a consequence, drying rates may be increased, and handling care becomes less critical.

Abstract: Low attenuation, low dispersion of optical waveguides are provided by a process initiating with axial deposition of a high velocity core soot stream impinging on, a target at a high angle of incidence relative to the axis of rotation of the target. A core cylinder is built up axially by relative movement between the soot stream and target during deposition, the movement being non-constant in order to maintain a substantially constant diameter with a constant deposition rate. A cladding layer is then built up by deposition of soot radially on the core. Subsequent drying and sintering provides a vitreous preform which may be drawn directly into optical waveguides. Alternatively, the sintered product may be drawn down to smaller rods, which then are covered with further deposited soot cladding to a desired final thickness, and after further drying and sintering may be drawn to optical waveguides.

Abstract: A method for producing mineral wool of a material which is highly fluid at an elevated liquidus temperature in particular above 1,200.degree. C., with a viscosity of less than 5,000 poises at liquidus temperature, is proposed wherein the molten mineral material, after having destroyed all nuclei of crystallization, is supplied into a spinner (1') the peripheral wall (19) of which comprises a multiplicity of orifices with small diameters wherethrough said molten material is centrifuged to form filaments which, in a given case, are subjected to a supplementary attenuating effect of a preferably hot gas flow flowing along said peripheral wall (19) of said spinner (1') and generated by a concentric annular external burner (13). If fiberization of such a material is effected in the traditional way, a great proportion of unfiberized particles in the product will result.

Abstract: A method of producing an oxide glass thin film includes a process to obtain a transparent glass film, in which volatilization of additives in a porous film deposited is effectively suppressed and which can provide an oxide glass thin film having a desired arrangement of refractive index with a low optical loss. The method is for producing an oxide glass thin film, in which glass fine particles mainly containing SiO.sub.2 with additives are deposited on a substrate to form a porous thin film and then heated to form a transparent glass film. In the method, vapor of oxides of additive components is mixed in an atmosphere in which the porous thin film is heated to form the transparent glass film, whereby stopping the volatilization of the additives in the porous film deposited, preventing diffusion of the additives added to a core layer, and preventing the volatilization of glass transition temperature lowering components of additives (P.sub.2 O.sub.5, B.sub.2 O.sub.3, GeO.sub.2, etc.).

Abstract: In accordance with the invention, the index of refraction of a region of a glass body is selectively increased by treating the material with hydrogen and then simultaneously applying heat and actinic radiation to the region. Preferably the body is heated to a temperature in excess of 150.degree. C. and the heat and radiation are simultaneously applied. The result is a substantial and long-lived increase in excess of 5.times.10.sup.-5 in the refractive index of the irradiated region. This process can be used to make and adjust a variety of optical waveguide devices such as photoinduced Bragg gratings.