Comparison of the N times mode-lines technique to the inverse technique in refractive index profile reconstruction

Abstract

A single-mode waveguide is fabricated using ion exchange in a molten bath of KNO 3 salt. The mode effective index is measured using a mode-lines (M-lines) experiment. The waveguide is then etched, and the M-lines experiment is performed again. The two measurements are sufficient for refractive index profile (RIP) reconstruction, which is assumed to be Gaussian. The reconstructed profile is checked using a numerical technique and is then compared to the inverse technique, showing the inverse technique limitations.