Otto Hans-Jürgen, Stutzki Fabian, Jansen Florian, Eidam Tino, Jauregui Cesar, Limpert Jens, Tünnermann Andreas
Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Albert-Einstein-Str. 15, 07745 Jena, Germany.
Opt Express. 2012 Jul 2;20(14):15710-22. doi: 10.1364/OE.20.015710.
The temporal behavior of mode instabilities in active large mode area fibers is experimentally investigated in detail. Thus, apart from the onset threshold of mode instabilities, the output beam is characterized using both high-speed camera measurements with 20,000 frames per second and photodiode traces. Based on these measurements, an empiric definition of the power threshold of mode instabilities is introduced. Additionally, it is shown that the temporal dynamics show a transition zone between the stable and the unstable regimes where well-defined periodic temporal fluctuations on ms-timescale can be observed. Finally, it is experimentally shown that the larger the mode-field area, the slower the mode-instability fluctuation is. The observations support the thermal origin of mode instabilities.
对有源大模场光纤中模式不稳定性的时间行为进行了详细的实验研究。因此，除了模式不稳定性的起始阈值外，还使用每秒20000帧的高速相机测量和光电二极管轨迹对输出光束进行了表征。基于这些测量，引入了模式不稳定性功率阈值的经验定义。此外，研究表明，时间动态在稳定和不稳定状态之间显示出一个过渡区，在这个过渡区可以观察到毫秒时间尺度上明确的周期性时间波动。最后，实验表明，模场面积越大，模式不稳定性波动越慢。这些观察结果支持了模式不稳定性的热起源。
