Abstract

Efficient fiber-waveguide coupling is indispensable in LiNbO₃ waveguide devices such as phase modulators for PSK coherent systems. To reduce fiber-waveguide coupling loss, several investigations, that try to optimize Ti diffusion parameters, have been reported¹⁾²⁾. However, in these investigations, fiber-waveguide-fiber insertion loss has been limited to 1 dB, because of the asymmetry of the waveguide depth mode. Thus, the depth index profile symmetrizing is essential to reduce fiber-waveguide coupling loss.

© 1986 Optical Society of America