Fabrication and properties of a 4 × 4 Linbo₃ optical matrix switch

To realize channel cross-connecting in optical communications systems, a high speed optical matrix switch was fabricated using z-cut LiNbO₃. Four 2 × 2 directional couplers were integrated on one substrate for construction of a 4 × 4 switch. Single-mode optical waveguides were formed by Ti-diffusion at a wet O₂ atmosphere. Ti-diffusion profile, refractive index variation and waveguide morphology were analyzed by SIMS, Prism coupler and SEM, respectively. The optical properties of the fabricated switch was measured in terms of insertion loss, cross-talk, spectral flatness and switching speed.