| 摘要 |
PROBLEM TO BE SOLVED: To provide a photo detector for detecting light with high efficiency in a straight state without refracting an optical fiber. SOLUTION: A high refractive index 5 that is formed by filling a material with a higher refractive index than a core 3 into a recessed part 4 that is formed by deleting the clad part partially or entirely is provided at a clad part 2 of an optical fiber 1. |
