A method of fabricating a fused fibre optic coupler includes disposing two or more segments of optical fibre under longitudinal tension. The tensioned fibre segments are preheated to a temperature sufficient to soften the segments and thereby substantially relieve their tension by inelastic stretching of the segments. After the segments have cooled, the fibre segments are re-tensioned and then heated while in intimate side-by-side contact to a temperature sufficient to cause the fibre segments to fuse together.
To make a fused fiber coupler (1) which is especially suited as a pump coupler for use in fiber amplifiers, exhibits low sensitivity to polarization, and can be spliced in with low loss, commercially available single-mode fibers are employed. After completion of an elongating process and interruption of heat from a heat supply, the input-fiber pair (fiber ends 4, 5) and the output-fiber (fiber ends 6, 7) of two fused lengths of the fiber (2, 3) are twisted by 180.degree. about their common axis and fixed in this position.
A mask having a center hole for passing through a center fiber, which is one of multiple fibers, and multiple surrounding holes for passing through surrounding fibers, which are the remainder of the multiple fibers, and a stress adjusting unit for holding stresses generated in the center fiber and surrounding fibers to a desired constant value, respectively, are installed. The surrounding fibers are rotated around the center fiber by rotating the mask. The center fiber and the surrounding fibers that have been twisted around the center fiber are heated with a heating apparatus and drawn. The center fiber and the surrounding fibers are fixed using a clamp installed between the stress adjusting unit and the heating apparatus.
The invention provides a method for fabricating a polarization independent narrow channel wavelength division multiplexing fiber optic coupler, comprising the steps of: holding two optical fibers in an abutting longitudinal relation along a predetermined length of the fibers; injecting light energy into one of the fibers; fusing the optical fibers together along the predetermined length to form a fused length of a fiber optic coupler; elongating the fused length of the fusing optical fibers; measuring the light energy output from the ends of the first and second fibers; ceasing the fusing and elongating when the measured light energy output from the ends of the first and second fibers indicates that a predetermined number, N.sub.S, of one-half power transfer cycles have occurred in the coupler, where the N.sub.S th one-half power transfer cycle occurs within a K.pi. phase region of a polarization envelope associated with the coupler, where K is a positive integer.
The present inventions pertain to a method of applying a solid protective coating to articles, to a system capable of depositing a solid film layer on articles, and to hermetically sealed articles. In particular, films are deposited on fused quartz substrates, optical fibers, and other items requiring a hermetic seal by a single or multiple beams laser-induced chemical vapor deposition [LCVD]. According to the present inventions, the protective layer can be deposited on the articles to be hermetically sealed in an open environment at atmospheric pressure and ambient temperature whereby the coating process may occur outside the confines of an enclosure. A coaxial precursor and non-reactive laminar gas jet configuration insulates the deposition area from oxygen and other aerial impurities. Moreover, the present inventions insulate items from corrosion resulting from hydrogen or water penetrating the items' surfaces, maintain the items' mechanical properties, and preserve the integrity of optical signal transmission of optical fibers.
An arrangement (apparatus and method) for hermetically sealing a fiber optic device. The fiber optic device includes a device body such as an optical coupler or a multiplexer coupled to exposed regions of optical fibers. The fiber optic device is hermetically sealed by forming metal seals such as pure aluminum blocks on exposed regions of the optical fibers. The blocks are formed by injecting molten aluminum into molds, during which the molten aluminum bonds to the optical fiber chemically and forms a compression seal on the optical fibers during cooling. The metal seals are then used to define a boundary for substrate bodies used to enclose the fiber optic device, where a hermetic seal is formed between the metal seals and the substrates by compressing the substrates onto the metal seals. Hence, a hermetic seal may be easily implemented on an existing fiber optic device without the necessity of adhesives.
