Abstract: Techniques and systems are described for reducing splice loss in an optical fiber transmission line. One described technique includes splicing together at a splice point a first fiber having a first modefield diameter to a second fiber having a second modefield diameter larger than the first modefield diameter. The splice point is heated to a core expansion temperature to cause a controlled thermal diffusion of core dopant in the first fiber in order to reduce modefield mismatch between the first and second fibers. Splice loss is then reduced by heating the splice point to a differential diffusion temperature to cause a controlled diffusion of a cladding dopant in the first fiber, while maintaining the expanded core.

Abstract: Techniques and systems are described for splicing together first and second optical fibers. A thermal treatment station is described, having a chassis, a fiber holding block for holding a pair of optical fibers that have been spliced together at a splice point, the fiber holding block including a cutaway portion exposing the splice point, and a torch, the fiber holding block and the torch being mounted to the chassis such that the positions of the splice point and the torch can be adjusted with respect to each other so that the splice point lies in the flame. A technique for splicing together two optical fibers is further described, in which the optical fibers are first spliced together using a fusion splicer and then thermally treated by positioning the splice point in a flame while monitoring splice loss.

Abstract: Techniques and systems are described for reducing splice loss in an optical fiber transmission line. One described technique includes splicing together at a splice point a first fiber having a first modefield diameter to a second fiber having a second modefield diameter larger than the first modefield diameter. The splice point is heated to a core expansion temperature to cause a controlled thermal diffusion of core dopant in the first fiber in order to reduce modefield mismatch between the first and second fibers. Splice loss is then reduced by heating the splice point to a differential diffusion temperature to cause a controlled diffusion of a cladding dopant in the first fiber, while maintaining the expanded core.

Abstract: Techniques and systems are described for splicing together first and second optical fibers. A thermal treatment station is described, having a chassis, a fiber holding block for holding a pair of optical fibers that have been spliced together at a splice point, the fiber holding block including a cutaway portion exposing the splice point, and a torch, the fiber holding block and the torch being mounted to the chassis such that the positions of the splice point and the torch can be adjusted with respect to each other so that the splice point lies in the flame. A technique for splicing together two optical fibers is further described, in which the optical fibers are first spliced together using a fusion splicer and then thermally treated by positioning the splice point in a flame while monitoring splice loss.