| 摘要 |
PURPOSE:To suppress the scattering loss of both corner parts of the upper part of a core and to improve the transmission characteristic by forming a buffer layer between the core and the upper clad. CONSTITUTION:On a substrate 11, the lower buffer layer 12, the lower clad 13, a core 14 and a buffer layer 15 are formed in this order, and also, both side faces of the core 14 and the upper face of the buffer layer 15 are covered with the upper clad 16. Also, a relation of a refractive index n1 of the core 14, a refractive index n2 of the lower clad 13, a refractive index n3 of the upper clad 16 and a refractive index n4 of the buffer layer 15 is set to n1>n2, n1>n3, and n1>n4. In such a way, since the buffer layer 15 is formed between the core 14 and the upper clad 16, no scattering loss is generated in both corner parts 14a, 14b of the upper part of the core 14, and the transmission characteristic is improved. |
