Chemical etching of optical fibers to produce conical tips prior to fiber lensing.

As part of a process to form lensed fibers for laser packages, tapered tips are formed on optical fibers by etching the fibers in a hydrofluoric acid solution beneath an organic layer. To improve the yield of the subsequent fiber lensing step, it is desirable to reduce the length of etched tips. Theoretical prediction of taper shape as a function of capillary constant and contact angle is presented. For the range of fluid properties characteristic of the organic/acid/fiber system, taper shape falls into a limiting, conical regime, in which the shape depends primarily on contact angle. The effects of a wide variety of surfactants on contact angle and cone length are described. Nonionic surfactants generally have the greatest influence on contact angle, if the concentration is not high enough to form surface micelles on the fiber.