| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high isolation optical fiber type optical component which has its cladding mode coupling loss suppressed. SOLUTION: This optical fiber 1 is constituted by covering a core 2, formed by covering a center core 3 with a side core 4, with a cladding 5. Specific refractive index differences Δ1, Δ2, and Δ3 of a center core 3, side core 4, and clad 5 with respect to pure quartz are so related that Δ1>Δ3>Δ2, and is provided with the formation part 6 of a fiber grating in which the refractive index of the center core 3 varies periodically along the optical fiber optical axis Z. Thus, the side core 4 which has the smaller refractive index than the cladding 5 is provided around the center core 3 and then a propagation mode in which light is propagated while confined to the core 2 is made small. Then, the cladding coupling loss, due to the coupling of a reflection mode in which the light reflected by the fiber grating formation part 6 leaks out to the clad 5 and propagates and the propagation mode, is suppressed. |
