摘要 |
A low-cost optical coupling circuit that enables high-efficiency coupling between an optical transmission line 4 and a photodetector element 2 is provided with an optical transmission line 4 and a photodetector element 2, both located on a substrate 1. The substrate 1 propagates light and receives emitted light L2 from the optical transmission line 4. A filler material 8 having a refractive index that is either equivalent to or lower than the refractive index of the core of the optical transmission line 4 fills the space between the optical transmission line 4 and photodetector element 2.
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