| 摘要 |
PURPOSE:To realize a flush type single mode light guide consisting of a waveguide having nearly a circular or elliptical shape without requiring electric field impression by executing heat ion exchange in both the 1st stage and 2nd stage of a stage for ion exchange and specifying the ion exchange conditions of the 1st and 2nd stages. CONSTITUTION:A glass substrate 1 contains the univalent ion selected from a group consisting of univalent alkali ion, univalent Tl ion and Ag ion for ion exchange. After a coating film 2a for controlling the ion exchange is deposited by evaporation on one face of the substrate 1, an aperture 2c of a prescribed waveguide pattern is formed thereon to form a mask film 2b. The substrate 1 which is subjected to the 1st stage of the heat ion exchange treatment in a 1st fused salt 4a then to the removal of the mask film 2b is thereafter subjected to the 2nd stage of the heat ion exchange treatment in a 2nd fused salt 4b. The ion exchange is so executed in this case that the products D1t1 and D2t2 of the 1st and 2nd effective ion exchange constants D1, D2 and ion exchange time t1, t2 satisfy the equations I and II. |
