Influence of surface errors on the performance of EFPI based on GRIN lenses

The graded index (GRIN) lens reduces the divergence angle of the beam exiting from the lead-in optical fiber, which results in the increasing of F–P cavity mirror areas. Surface errors of the increased mirrors cannot be ignored due to the machining tolerance. The influence of surface errors on the performance of the fiber extrinsic Fabry–Perot interferometer (EFPI) is researched. Theoretical analysis and numerical simulation results demonstrate that surface errors will diminish the interference contrast. The larger the surface error, the smaller the interference contrast will become. The results will contribute to the design of an EFPI with a certain interference contrast.