Abstract
Fiber-optic probes for sensing and imaging applications often employ sections of graded-index (GRIN) fiber to refocus the diverging light from the delivery fiber. Such GRIN fiber microlenses possess aberrations which can cause significant distortions of the focused output beam. Using a numerical beam propagation method, we analyze the output beams resulting from index profiles that exhibit a central dip or a deviation from the ideal parabolic shape. Our method is in good agreement with experimental data and it enables the accurate simulation of fiber probes for biomedical applications using non-ideal or custom-engineered GRIN fibers with arbitrary refractive index profiles.