摘要：

A coaxial light-guide system includes a coaxial light-guide optical fiber which is fabricated by having refractive index profile set on radii. Thus the coaxial circular outer-cladding and the axial inter-cladding have the same refractive index. The light guide refractive index profile center is moved from the axis to the entire radii of the optical fiber. Light propagates between the axial inter-cladding and the coaxial circular outer-cladding. Such a new positioning prevents center-dip in the refractive index profile that occurs to the prior optical fiber after fabrication is finished. The coaxial single-mode optical fiber of the invention has a greater optical flux than the prior optical fiber, and can increase communication distance. Coupled with a coaxial light source and photodiode of the invention that have an coaxial inner and outer conductors to supply electric power and a plurality of annular semiconductor layers interposed therebetween, energy waste caused by prior edge-emitting elliptic light source injecting in a circular core can be eliminated.

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