| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital optical switch which is operative with low voltage. SOLUTION: A single mode optical waveguide 12 is formed on a Z-cut LiNbO3 substrate 11 by diffusing Ti on the substrate 11. This single mode optical waveguide 12 is branched to two pieces of arm waveguides 14, 15 having the respective opening angles ofθ2 from a tapered part by widening the width of the waveguides by a tapered waveguide 13 having a taper angle ofθ1. The width W1 of the taper waveguide 13 is set wider than twice the width W of the arm waveguides 14, 15. The arm waveguides 14, 15 are provided with a gap between their ends. The equiv. refractive index in the central part of the arm waveguides 14, 15 is lowered by this gap 14, by which the light confinement is weakened. |
