Coherent reflectometry of optical fiber amplifiers

The reflectivity of commercially available erbium-doped fiber amplifiers (EDFAs) was measured with coherent optical frequency domain reflectometry (C-OFDR). Reflections at the output isolator as well as the distributed gain along the erbium-doped fiber could be observed thanks to the high amplified spontaneous emission (ASE) rejection due to the coherent detection. Gain figures obtained with the OFDR technique are in good agreement with single-pass direct gain measurements.