| 摘要 |
PURPOSE:To obtain an optical switch corresponding to a specified coupling length in which correction is easily performed by forming a coating which has smaller refractive index than an optical waveguide layer and has larger refractive index than air on the optical waveguide layer on the side of the outer side surface of each clad layer. CONSTITUTION:The coating 15 which has smaller refractive index than the light guide layer and larger refractive index than the air is formed on the optical waveguide layer 12 on the respective side of the outer side surfaces of the clad layers 13 and 14. Since the coating 15 has smaller refractive index than the light guide layer and larger refractive index than the air, it acts to increase equivalent refractive index in the optical waveguide layer area including the coating 15. Therefore, the refractive index in the optical waveguide layer area including the coating 15 gets larger than that of the optical waveguide layer where the coating between the respective clad layers is not formed. Then, it acts to make the connection of electric field in the optical waveguide layer between the respective clad layers weak and to make the coupling length Lc long, and the value of the coupling length Lc is controlled by the thickness of the coating 15. Thus, the deviation is corrected even though the coupling length Lc of the optical switch is deviated from a designed value because of errors in production. |
