| 摘要 |
An optical fiber communication system according to the invention comprises an optical fiber filter that can be manufactured at low cost and that can be conveniently incorporated into the system, substantially like a conventional fiber jumper. The filter comprises a length L of axially uniform optical fiber selected to have substantially no loss (e.g., <1 dB) at a wavelength lambda 1, and to have relatively high loss (e.g., >20 dB) at a wavelength lambda 2. The length L will typically be less than 100 m. In one embodiment the optical fiber is a single mode optical fiber at lambda 1 (e.g., 1.3 mu m) that does not have a guided mode at lambda 2 (e.g., 1.55 mu m). In another embodiment the fiber contains a dopant that does substantially not absorb radiation of wavelength lambda 1, but substantially absorbs at lambda 2. In the second embodiment, lambda 1 can be greater than lambda 2. Fiber filters according to the invention can be advantageously used in a variety of communication systems, and exemplary systems are disclosed.
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