| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber having high detecting efficiency. SOLUTION: The optical fiber, which is composed of a core 12 propagating light and a clad 13 which covers the core 12 and shields light propagating the inside of the core 12, is provided with a small diameter part in which the thickness of the clad 13 at one end of the optical fiber 11 is thinned, a projected part 65 in which the tip end of the core 12 projected from the clad 13 of the small diameter part is sharpened in a tapered shape, a light shielding metallic coating layer 66 which is formed on the surface of the projected part 65, and an opening part 68 in which an opening diameter exposing the tip end of the projected part 65 outside from the metallic coating layer 66 is not more than the wavelength of light, and the core 12 is made of pure quartz SiO2. |
