Noise figure measurements on Nd and Yb doped double-clad fiber amplifiers

We present comparative noise figure measurements on neodymium and ytterbium doped double-clad fiber amplifiers. While the neodymium doped amplifier showed the quantum-limited noise figure of 3 dB, the ytterbium doped amplifier exhibited excess noise due to its three-level system. We compared optical and electrical methods with respect to the accuracy and the suitability for high power measurements.