Optical Fiber Shifts and Shear Stains in V-Groove Arrays for Optical MEMS Packaging

The objective of this study is to investigate optical fiber shifts and shear stains in V-groove arrays for optical microelectromechanical system packaging, when the arrays are subjected to temperature cycling. Thermally induced optical fiber shifts in the joints consisting of an optical fiber, epoxy adhesive, and silicon substrate were simulated using a finite element analysis (FEA) package ANSYS. Experiments using real-time Moire´ interferometry were also performed at temperatures of 25, 40, 60, 85 and 100°C for confirmation of the analysis results. The study revealed that thermally induced fiber shifts increased with the number of V-groove channels. The shear strains at the fiber and silicon interface in the fiber joints increased as the V-groove channel was further away from the neutral point of the fiber array packages. The optical coupling loss is the greatest during thermal loading for the outer fiber in the four channel V-groove array. Optical loss of 0.334 and 0.346 dB was calculated using the fiber shift values obtained from the FEA and experimental results, respectively. The effect of fiber shifts, especially the shift of the fiber that is positioned at the outermost V-groove in the array, cannot be ignored.