Abstract: Techniques are described for reducing splice loss between a pair of optical fibers. A first fiber is spliced to a second fiber at a splice point. A region of the spliced fibers, including the splice point, is thermally treated to cause a controlled diffusion of dopants in the region. A controlled tension is then applied to the splice region while heating it to a predetermined temperature to produce a controlled change in the splice region's strain state. Further described is a heat and tension station for performing a heat and tension technique on a pair of spliced fibers.

Abstract: A package is described that includes a sleeve having at least one end defining an opening. The sleeve further includes at least one pair of locking tabs extending therefrom, each locking tab including a locking edge, each locking tab being folded inwards into the opening. The package further includes a rigid end cap dimensioned to fit closely within the opening, the end cap including a rim designed so that, when the end cap is inserted into the opening, the rim engages the sleeve end and prevents the end cap from being inserted further into the opening. The end cap further includes a channel for receiving the pair of locking tabs, the channel having a ledge that engages the locking edge of each locking tab to prevent the end cap from being removed from the sleeve opening. Another described package provides a release mechanism for allowing an end cap to be removed without causing damage to the package.

Abstract: Techniques are described for fabricating a preform from a soot body. In one described technique, a soot body is loaded into a substrate tube, and the position of the soot body is stabilized within the tube. The tube is then rotated around its longitudinal axis. Heat is applied from a heat source to the substrate tube at a first end of the soot body to cause the first end of the soot body to begin to sinter and to cause the substrate tube to begin to at least partially collapse around the sintered portion of the soot body. The heat source is then advanced along the substrate tube and the soot body to cause a progressive sintering of the soot body, and to cause a progressive, at least partial, collapse of the substrate tube around the sintered portion of the soot body.

Abstract: A fiber coating applicator includes a chamber and a cup positioned over the chamber. The cup is connected to the chamber by an entrance aperture. The chamber includes an exit aperture opposite the entrance aperture. The cup, entrance aperture, chamber, and exit aperture define a pathway for a fiber, such as an optical fiber, to be coated. The chamber further includes an input port for pumping a coating material into the chamber. The entrance aperture is dimensioned such that as a fiber travels along the pathway and coating material is pumped into the chamber, coating material travels upward through the entrance aperture around the fiber into the cup, the upward flow of coating material being restricted by the fiber and entrance aperture such that there is a hydrostatic pressure in the chamber. The exit aperture is dimensioned to shape coating material around a fiber traveling along the pathway.

Abstract: Systems and techniques are described for fabricating a low-loss, high-strength optical transmission line. In one described technique, a first fiber is spliced to a second fiber at a splice point. The spliced fibers are loaded into a heat treatment station, where a gas torch flame is used to thermally treat a splice region including the splice point, with the thermal treatment reducing splice loss between the first and second fibers. While heating the splice region, a dry gas is purged around the torch flame during the heat treatment process to avoid water at the surface of the spliced fibers. According to further described techniques, a purging gas is fed to the torch flame to purge dust particles from the flame, and after the heat treatment has been completed, the torch flame is used to restore the glass surface of the spliced fibers. Additionally described are torch assemblies for fabricating low-loss, high-strength optical fiber transmission lines.

Abstract: Techniques are described for reducing splice loss by using an ultra-short bridge fiber to splice together a first fiber and a second fiber having different modefield diameters. The ultra-short bridge fiber has an intermediate modefield diameter between the modefield diameters of the first and second fibers. In one described technique, a first end of the ultra-short bridge fiber is spliced to a lead end of the first fiber at a first splice point. The bridge fiber is then cleaved at a predetermined distance away from the first splice point. A lead end of the second fiber is then spliced to cleaved end of the bridge fiber at a second splice point. A single protective splint is then installed that covers the bridge fiber and the first and second splice points. Further described is an optical fiber transmission line including an ultra-short bridge fiber.

Abstract: Optical fibers are described that exhibit reduced splice loss. Further described are techniques for fabricating optical fibers exhibiting reduced splice loss. One described fiber includes a plurality of regions, one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension, a strain is frozen into the higher viscosity region. A lower viscosity buffer layer is sandwiched between the higher viscosity region and the lower viscosity region. The buffer layer isolates the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

Abstract: Systems and techniques are described for monitoring a pre-splice heat treatment of an optical fiber. In one described technique, a lead end of a first fiber is prepared for splicing. The lead of the fiber is then loaded into a heat treatment station. While heating the lead fiber end, an optical time domain reflectometer is used to measure reflected backscatter loss from the lead fiber end. The lead fiber continues to be heated end until the measured reflected backscatter loss from the lead fiber end reaches a predetermined level. At that point, the heat treatment is discontinued.