| 摘要 |
PURPOSE:To suppress the radiation loss by continuously changing the refractive index distribution in the axial direction while keeping the normalized frequency of a fibrous element, which consists of a core layer and a cladding layer, approximately constant. CONSTITUTION:A fiber type optical wave circuit element consists of a core layer 51 and a cladding layer 52, and the cross section of the core layer 51 in both ends 51a and 51b has about circular symmetrical shape, and the normalized frequency is kept approximately constant between both ends 51a and 51b and the refractive index distribution is so set that the electromagnetic field distribution is continuously spread in the axial direction. Consequently, the incident optical wave from one end 51a keeps the peculiar mode while suppressing the radiation loss during propagation and reaches the other end 51b. If the cross section shape of the core layer 51 in both ends 51a and 51b is set in accordance with the electromagnetic field distribution of the optical wave circuit element connected to both ends 51a and 51b, the radiation loss accompanied with mismatching of the electromagnetic field distribution due to connection is suppressed. |
