| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in which a high cost is required in an machining operation of making high precision and minute circular openings in a preform rod, and in which, while fewer circular openings reduce the machining cost, excessively fewer openings bring failure of obtaining prescribed characteristics as well as making transmission loss greatly different depending on a bending direction of the optical fiber. SOLUTION: The optical fiber is provided with a core 10 and a clad 11 surrounding the outer periphery of the core 10 and having a higher refractive index than the core 10. Near the outer periphery of the core 10 in the clad 11 and in parallel to the center axis of the core 10, the optical fiber has five circular openings 12 arranged at nearly an equal distance from the center axis. These circular openings 12 are positioned at the apexes of a near regular pentagon in the cross sectional view of the core 10. COPYRIGHT: (C)2007,JPO&INPIT |
