Effect of humidity on optical fiber-adhesive bonding

Optical adhesives serve a means of structural attachment as well as provide an optical path between connecting elements in an optical modules. The aim of this study was to determine the displacement and normal strain induced in an optical fiber as a result of moisture absorption within the optical adhesive of the module. The displacement and the strain of single mode fiber-adhesive joint on silicon optical bench (SiOB) were measured by Micro Moire interferometry (MMI). The experiments were performed on a module consisting of SiOB and single-mode-fiber attached in a V-groove with the help of a UV-curable adhesive. Moisture saturation of the optical adhesive within the optical package was achieved via the devised moisture uptake by the capillary effect setup and specimens were placed in the set up for one week. Strain in the adhesive was measured by MMI during the moisture desorption, at 60oC. The maximum V and U field displacement demonstrated by the fiber was 0.66μm and 0.59μm respectively. The V and U field induced recovery strain of 0.00488 and 0.00438 respectively as a result of the saturation process grounds the postulation that moisture does indeed affect the optical fiber's relative position within the optical module.