| 摘要 |
Attenuation of an optical signal (25) at the end (43) of an optical fiber (21) is achieved by positioning a high absorption region (24) at the end of the fiber. A first embodiment teaches a highly doped annulus (24) within a tapered end (5) of the fiber. The highly doped annulus about the light transmitting core (22) serves to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped annulus is in proximity to the core due to the tapering. The annulus, which is preferably heavily doped with a rare earth such as erbium, absorbs the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface. <IMAGE> |
