Power noise sources of single frequency fibre amplifiers

Single frequency lasers are primarily used for precision measurements and therefore their noise properties are of critical importance. Most of the analysis in this field is concerned with the high frequency noise as characterized by the noise figure. However, for many applications the low frequency region up to 100 kHz is equally important. This paper shows how the noise in this frequency region can be estimated from the amplifier dynamics and the incoming pump and signal noise as long as additional noise influences can be neglected. Furthermore, additional influences which can be dominant in high power amplifiers are identified.