| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to prevent the occurrence of crack in a juncture and to execute connection to another optical waveguide with high reliability by making the thickness of a clad (glass) layer at the juncture nonuniform and forming a thin clad exclusive of the periphery of a core or forming the clad only in the periphery of the core. SOLUTION: Only the lower clad layer 32 is made thick. If the clad layer 32 in the lower part of the core 34 is eliminated, stresses are substantially eliminated in terms of stress, but the waveguide structure does not exist any more and, therefore, the loss increases. Then, the elimination of the clad around the core 34 is not possible. The clad is made to remain only around the core 34 and the lower part clad layer 32 is eliminated or is made thin in the other parts by taking advantage of the fact that the ratio of the sectional area of the core 34 occupying the cross section over the entire part of the plane type optical circuit is small. As a result, the internal stresses are drastically decreased. Then, the occurrence of the crack does not arise any more and the connection of the plane type optical circuit and the fiber with the excellent long-term stability is made possible. |
