| 摘要 |
A channel add/drop filter-coupler includes two single-mode optical fibers that have different refractive index profiles. Each optical fiber has a propagation constant that is a function of frequency. A portion of the cladding of each fiber is removed to form a planar surface on each fiber. A plurality of channels is formed in one or both of the planar surfaces. The channels are spaced with a predetermined channel period that is inversely proportional to the difference between the propagation constants of the two fibers of the filter-coupler at the desired center frequency of the filter-coupler. The filter-coupler is completed by joining the two fibers at the planar surfaces. The coupling of the filter-coupler may be tuned by moving one fiber longitudinally, angularly, or, preferably, laterally with respect to the other fiber. Furthermore, the filter response of the filter-coupler is advantageously shaped by varying the location of the channels within the predetermined channel periods or by varying the depth or the width of the channels. |
