New optical configuration for nondestructive measurements of refractive index profiles of LiNbO(3) waveguides

A direct and nondestructive measurement technique for the determination of the refractive index profiles of one- and two-dimensional LiNbO(3) waveguides is presented for the first time to our knowledge. The technique generalizes the refracted near-field method, which is well known for optical fiber characterization. The spatial resolution and accuracy are 0.1 and 0.4 µm, respectively. The refractive-index calibration is done by an analysis of the near-field light power distribution, and its resolution is approximately 2 × 10(-4). The proposed experimental setup permits sample installation and data acquisition in a few minutes.