Refractive Index Proflling of Metal-difiused Planar Waveguides Using a Difierential Near-fleld Optical Microscopy

A difierential near-fleld scanning optical microscopy (DNSOM) was used to recon- struct the refractive index proflle of a Ti:LiNbO3 planar waveguide. The waveguide was measured at 633nm for single-mode operation. The reconstructed index proflle matches well with known index model of Ti:LiNbO3 waveguides. Guiding mode proflle calculated from fltted index model also shows good agreement with measured mode proflle.