| 摘要 |
PURPOSE:To improve the light transmittance of an optical fiber cable by providing a cooling layer by liquefied gas in a cable using ionic crystal optical fibers. CONSTITUTION:An optical fiber cable is constituted of a plurality of ionic crystal optical fibers 2, covering objects 3 thereof, a copper pipe 4 internally inserted with these members, a liquefied gas cooling layer 5 on the inner side of the pipe 4, a laminate 6 of an Al foil and glass wool on the outside circumferential surface of the pipe 4, a copper corrugated layer 7 on the outside thereof, and the outermost layer polyethylene sheath 8. The corrugated layer 7 is so set that a vacuum is created in its inside and this coupled with the laminate 6 shut off the heat from the ouside. If the optical fibers 2 are cooled by the cooling layer 5, not only the absorption in an ultraviolet region but also the absorption in a visible region decrease, thus resulting in increased light transmittance and improved performance of the cable 1. |
