Penninckx Denis, Montant Sébastien, Luce Jacques, Bordenave Édouard, Boursier Élodie, Rouyer Claude
Appl Opt. 2021 Sep 20;60(27):8277-8285. doi: 10.1364/AO.431738.
In order to smooth the focal spot of high-power energetic lasers, pulses are phase-modulated. However, due to propagation impairments, phase modulation is partly converted into power modulation. This is called frequency modulation to amplitude modulation (FM-to-AM conversion). This effect may increase laser damage and thus increase operating costs. For the first time, to the best of our knowledge, we have studied the impact of the Kerr effect in this process. We have shown that when the Kerr effect is followed by a dispersive transfer function, a dramatic increase of FM-to-AM conversion may occur for a particular kind of FM-to-AM conversion that we have named "anomalous." Hence, we should remove or compensate for one of the items of the sequence: phase modulation, anomalous FM-to-AM conversion, Kerr effect, or the dispersive function. We have assessed all these solutions, and we have found an efficient inspection method to avoid anomalous FM-to-AM conversion.
为了使高功率高能激光的焦点平滑，对脉冲进行了相位调制。然而，由于传播损伤，相位调制会部分转换为功率调制。这被称为调频到调幅转换（FM-AM转换）。这种效应可能会增加激光损伤，从而增加运营成本。据我们所知，我们首次研究了克尔效应在此过程中的影响。我们已经表明，当克尔效应之后是一个色散传递函数时，对于我们命名为“异常”的一种特定类型的FM-AM转换，FM-AM转换可能会急剧增加。因此，我们应该去除或补偿序列中的一项：相位调制、异常FM-AM转换、克尔效应或色散函数。我们评估了所有这些解决方案，并找到了一种有效的检测方法来避免异常FM-AM转换。
