| 摘要 |
PURPOSE:To prevent the noise from being aggravated by a Fabry-Perot resonator, by providing a single mode optical fiber, and optical connectors on both its ends, and forming a specific relation among a light velocity, the refractive index of the single mode optical fiber, spectral line width of a light source, and length of the single mode optical fiber. CONSTITUTION:An extension optical fiber cable is provided with a single mode optical fiber 1, and optical connectors 2, 3 provided on both its ends, and set so that length L of the single mode optical fiber, against spectral line width DELTAnuof a light source becomes a relation of L>>c0/(2n.DELTAnu), when the light velocity, and the refractive index of the single mode optical fiber are denoted by c0, and (n), respectively. In such a way, the mode interval of a Fabry-Perot resonator formed between the end faces of the single mode optical fiber is narrowed, therefore, the variation of a transmission light is averaged, the aggravation of noise due to the Fabry-Perot resonator can be prevented, and a stable operation can be obtained even against the disturbance of the light source and the single mode optical fiber. |
