Abstract

Proton exchanged (PE) waveguides are nowadays widely employed for different applications, ranging form integrated lasers to nonlinear optical devices. As it is well known, they allow only extraordinary guided modes to be supported, since the ordinary refractive index is decreased by proton exchange The knowledge of the ordinary refractive index profile is however of great importance for different reasons: i) essential features such as the crystallographic phase of the exchanged layer can be directly obtained if the ordinary refractive index change An0 is known [1]; ii) the propagation of TM guided modes in Z-cut waveguides, which are the most widely employed in QPM (quasi-phase-matched) structures, is affected by the ordinary refractive index profile; iii) if a single mode is supported by the extraordinary refractive index profile, a full characterization of the waveguide can still be achieved if the depth of the ordinary refractive index profile d₀ is determined (the depth of the extraordinary profile d_e coincides with the depth d of the exchanged layer and, thus, it is equal to d_o).

© 2000 IEEE