1 Department of Physics and Astronomy, Science and Technology, Aarhus University2 Interdisciplinary Nanoscience Center - INANO-Fysik, Ny Munkegade, Interdisciplinary Nanoscience Center, Science and Technology, Aarhus University3 unknown4 Department of Physics and Astronomy, Science and Technology, Aarhus University
A new method for direct writing of localized, circularly symmetric refractive-index changes in optical fibers with a femtosecond laser is demonstrated. The refractive-index changes are characterized using a novel approach employing comparison of numerical simulations to the measured far-field profiles of unmodified and modified fibers. From the analysis, a negative refractive-index change of −0.015 0.005 within a radius of 0.6 0.1 μm is determined.
Optics Letters, 2014, Vol 39, Issue 12, p. 3398-3401