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Summary form only given. Recently, we reported on a non-destructive, rapid measuring technique using an optical frequency domain reflectometer (OFDR). The OFDR is ideally suited for this type of measurement, as its range, resolution, and dynamic range match well with the required values. Further, due to the coherent detection used in the OFDR, disturbing ASE light is largely rejected. In this talk good quantitative results for the gain distributions in different types of EDF at 1550 nm using an improved OFDR with better resolution (mm), accuracy (0.25 dB), and stability will be given. The accuracy and reproducibility of the measured gain distributions are analysed in EDF with strongly varying doping levels and doping confinements.