Low-loss Coupling Analysis of APE LiNbO_3 Waveguides

Using the beam propagation method (BPM) ,the dependence of mode field parameters of APE LiNbO3 waveguides on the width, depth and surface refractive index increment of waveguide are studied. The results show that the mode field is influenced by all those parameters. The influence of waveguide parameters on the coupling efficiency between the fiber and APE waveguide is also discussed. The results show:in order to obtain the optimal coupling,the needed structure parameters of waveguide are different for different fiber. This conclusion is useful for the design and fabrication of the optical waveguide devices.