| 摘要 |
PURPOSE:To surely obtain the optical branching device or optical coupling device having desired characteristics by once producing a directional coupler constituting the optical branching device or optical coupling device, then changing the effective refractive indices of a pair of the optical waveguides thereof, and thereby adjusting the characteristics. CONSTITUTION:The directional coupler constituting the optical branching device or optical coupling device having a pair of the optical waveguides 4a, 4b is once produced on a substrate 1. A thin-film layer 5 is mounted over the entire surface on this substrate 1 by using such a material which decreases the absorption of the light propagated in the optical waveguides. a light emitting means 6 and measuring means 7, 7b are connected to the optical waveguides 4a, 4b and the coupling state of the optical waveguides 4a, 4b is measured. The optical waveguides mounted with the thin-film layer 5 are increased in the effective refractive indices thereof and, therefore, the confinement of the light into the optical waveguides is increased and the coupling length changes to a substantially increasing direction. The mounted thin-film 5 is, thereupon, subjected to such working as to gradually reduce its thickness, by which the optical branching device or optical coupling device having the desired characteristics is obtd. |
