| 摘要 |
Amplifier (700) includes an optical circulator (710) that receives an optica l signal through a first port (710-1) and outputs the signal to doped fiber (712) through second port (710-2). Pump light is supplied to doped fiber (71 2) from pump laser (716) via a filtering element, such as in-fiber Bragg gratin g (714), which is typically designed to reflect light at the desired signal wavelength, but transmit other wavelengths. Accordingly, signal light output from second port (710-2) is reflected back through fiber (712) by grating (714) to second port (710-2) and experiences gain during each pass through fiber (712). The reflected light is then output from a third port (710-3) an d passes through an optical dielectric filter (618) to receiver (315). Filter (618) can be provided to reduce ASE. In addition to or instead of filter (618), dielectric filter (735) can be provided at the output of pump laser (716). Typically, filter (735) is configured to transmit light at the pump laser wavelength (980nm or 1480nm, for example), but substantially reflect light at other wavelengths including ASE and signal light. Accordingly, pump laser (716) is effectively isolated from any ASE or signal light passing through grating (714) which could otherwise adversely affect performance of pump laser (716).
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