Comprehensive Modeling of Single Frequency Fiber Amplifiers for Mitigating Stimulated Brillouin Scattering

A universal model capable of handling various operating conditions has been developed for designing of high power single frequency fiber amplifiers. The model analyzes the impacts of pump configurations, fiber lengths, and fiber temperatures on amplifier performance. It shows that counter-pumped amplifiers are capable of generating several times more output than co-pumped amplifiers. To fully take their advantages and deliver the laser output, a delivery fiber should be properly designed to avoid unwanted SBS which can significantly undermine the amplifier performance. On the other hand, for applications requiring delivery fiber at relative low power, the co-pumped amplifier can be an alternative since it can use the gain fiber as the delivery fiber and thus eliminate requiring an additional delivery fiber. The model also analyzes possible approaches for suppressing SBS, such as applying additional heating, the use of SBS suppressing fiber, and increasing core diameter. It shows that applying additional heating to a co-pumped amplifier can increase the output by a factor of 1.7. Finally, the model concludes that a single frequency amplifier can achieve multiple kilowatts output by carefully choosing amplifier design and utilizing SBS suppression technique.