| 摘要 |
A method for making an optical fiber fusion joint between two dissimilar single mode optical fibers (10,40) where the fibers have different core sizes and/or different refractive index profiles due to different patterns of dopant. One fiber may be a standard step-index communication fiber with a 9 mum core diameter and a numerical aperture (NA) of about 0.1, and the second fiber may be a dispersion compensating fiber (DCF) with a multiple layer refractive index profile. The second fiber alternatively may have a smaller core and a higher NA, up to about 0.3. A diffused dopant region, with a gradual longitudinal variation in diffusion, is included adjacent to the splice. The diameter of the communications fiber core increases gradually within the diffusion region as the splice joint is approached along this fiber. The diffusion of the various dopants in the second fiber tend to cause its refractive index profile to converge optically to that of the diffused step index communication fiber. As a consequence of the gradually varying diffusion region, the optical losses associated with the splice are relatively low, even when there is relatively high mismatch between the mode field diameters and mode field shapes (at a signal wavelength) in the respective fibers. In another embodiment a fiber fattening technique is used to fatten the fibers in the region of the splice to reduce losses.
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