The most important consideration for the reliability of multi-channel V-groove modules on silicon substrate is the misalignment of the optical fibers during the thermal loading. Failure of the entire module can take place even due to the misalignment of the optical fiber in one of the channels. In this paper, the misalignment of single mode fiber in the optical module with two- and four-channels was measured by Micro Moire Interferometry for thermal loading. Temperature loads ranging from room temperature (25 degrees C) to 100 degrees C were applied to the modules. Displacements of the fiber in different channels depend on their respective position in the V-grooves. In the four-channel V-groove, the vertical misalignments of the fibers in centre were relatively high compared to the horizontal displacement for the same temperature loading. Finally, simulation results of 2.5 Gbps uncooled CWDM transceiver modules, for end-to-end fiber optic link performance, are presented to understand the effect of the fibers displacements on the signal fidelity. (c) 2005 Published by Elsevier B.V.