Effective refractive index change of X-cut Z-propagation Ti:LiNbO₃ waveguides by laser ablation

Laser ablation was applied to X-cut Z-propagation Ti:LiNbO₃ waveguides. The effective refractive index change of the waveguides after the ablation was measured for both TE and TM modes. The change is more sensitive to the ablation for the TE than for the TM mode. This phenomenon was confirmed by measuring the modal effective refractive indices of a nonablated and an ablated planar Ti:LiNbO₃ waveguide with the m-line method. A photoelastic effect that may cause the different effective index changes of the waveguide modes after ablation is discussed.