| 摘要 |
An active optical fiber for use in an amplifier or laser has an inner cladding and an outer cladding. An index grating is written into the inner cladding to provide coupling between cladding modes of pumping radiation conducted in the inner cladding. The periodicity of the index grating is selected to couple energy from cladding modes having minimal overlap with the core to cladding modes having relatively high overlap. The efficiency of pumping the radiation amplifying medium of the core is thereby improved. The fibre has utility in transmitters for broad band networks.
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