Abstract: A method for forming a doped optical fiber includes drawing the optical fiber from a doped glass supply at a draw speed and a draw tension sufficient to introduce a heat aging defect in the optical fiber. The optical fiber is treated by maintaining the optical fiber within a treatment temperature range for a treatment time while preferably maintaining the optical fiber within a treatment tension range to reduce the tendency of the optical fiber to increase in attenuation over time following formation of the optical fiber. Apparatus are also provided.

Abstract: A method of making 1.times.2 or 2.times.2 overclad couplers, switches and the like such that the process is more reproducible and loss characteristics are improved. Such couplers are typically made by inserting the stripped portions of two active optical fibers into a tube, heating the tube midregion to collapse it onto the fibers and stretching the central portion of the collapsed midregion to achieve the desired coupling characteristics. The improvement involves the insertion of one or two spacer fibers into the tube bore along with the active fibers to take up empty space that had been present in tube bore and to prevent an active fiber from sagging and crossing over the other fiber when the tube is heated during the tube collapse step.

Abstract: After a plurality of optical fibers are fused to make a fiber optic coupler, the ends thereof are glued to a substrate to provide the outwardly extending fibers with adequate pull strength. The glue can flow from the point of application toward the fused region where it can adversely affect the the device. To prevent the glue from flowing too far toward the fused region and yet permit sufficient flow to strengthen the fibers, a beam of UV light is directed onto the fibers at that predetermined point where glue flow should stop. When the glue is cured by the beam, it stops flowing. Thereafter, the remainder of the glue is cured.