Effects of thermally induced optical fiber shifts in V-groove arrays for optical MEMS

Thermally induced optical fiber shifts in the joints consisting of an optical fiber, epoxy adhesive and silicon substrate were simulated using a FEA (finite element analysis) package. Experiments using a real-time micro-moiré system were also performed at temperatures of 25, 40, 60, 85 and 100 °C for confirmation of the FEA results. The optical coupling loss, caused by the fiber shifts, of a single-mode fiber to fiber and a laser diode to a fiber was studied. The results revealed that thermally induced fiber shifts increased with the number of V-groove channels. The optical coupling loss is the greatest during thermal loading for the outer fiber in the four channels V-groove array. Optical losses of 0.334 and 0.346 dB for fiber-to-fiber coupling and 1.54 and 1.56 dB for laser diode to fiber coupling were calculated using the fiber shift values obtained from the FEA and experiments, respectively, for the outermost fiber joint in the four channels V-groove array at 100 °C. The effects of fiber shifts especially the shift of the fiber that is positioned at the outermost V-groove in the array cannot be ignored.