Method of reinforcing optical fiber coupler.

摘要

A method of reinforcing a multiple optical fiber coupling unit is provided including the steps of removing a portion of longitudinal coatings of optical fibers (11) of the multiple optical fiber coupling unit to expose glass portions (12) of said optical fibers; fusing a portion of the exposed glass portions so as to optically couple the optical fibers; extending the fused portion to a predetermined state; fixing non-extended portions of the exposed glass portions on a first reinforcing substrate (15) with a first adhesive (14); and fixing the first reinforcing substrate on a second reinforcing substrate (16) with a second adhesive (17). The multiple optical fiber unit coupler made by this method has a transmission characteristic that does not substantially change even with a temperature change and under high humidity. The first reinforcing substrate (15) is preferably made of a material such as quartz, LCP (liquid crystal polymers) or the like, which has a coefficient of linear expansion substantially equal to that of the optical fibers (10). Since the expansion coefficients are substantially equal, stress exerted on a light-coupling portion of the coupler due to thermal expansion/shrinkage of the substrate caused by a change in circumferential temperature, is prevented. The adhesive (14) may be, for example, an adhesive of the thermosetting or ultraviolet-setting type of a urethane acrylate group, an epoxy group, or an cyanoacrylate group. It is preferable to use a material having a coefficient of linear expansion substantially equal to that of optical fibers and having the same shock resistance as that of the optical fibers as the second reinforcing substrate (16). Since the first and second reinforcing substrates (15) and (16) are fixed to each other through the soft adhesive (17), the coefficient of linear expansion is not always substantially equal to that of the optical fibers. Therefore, it is preferable to use a material, such as LCP, Invar, or the like for the reinforcing substrate (16). Further, the shape of the substrate (16) is preferably box-like or cylindrical so as to assure sealing in order to protect small-diameter portions of the coupler and to prevent dust from entering the coupler. <IMAGE>