OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To obtain an optical fiber with improved light transmission efficiency by forming an air layer between the outer face of a core and the inner face of a tube and maintaining the air layer. SOLUTION: A transparent core 1 having flexibility is arranged in a tube 2 having a larger inner diameter than the outer diameter of the core 1 and having flexibility. An air layer 3 is present between the outer face of the core 1 and the inner face of the tube 2. Holding members 4 are disposed at some distance in the air layer 3 so that the air layer 3 acts as a clad between the core 1 and the tube 2 for the optical fiber. Or, a holding member 4 may be used which is prepared by encapsulating a member 6 consisting of air or a material having a refractive index equal to that of air in a hollow member 5 consisting of a material having a refractive index equal to that of the core 1.