Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev E. 2018 Mar;97(3-1):033201. doi: 10.1103/PhysRevE.97.033201.
In its usual implementation, the Raman amplifier features only one pump carrier frequency. However, pulses with well-separated frequencies can also be Raman amplified while compressed in time. Amplification with frequency-separated pumps is shown to hold even in the highly nonlinear, pump-depletion regime, as derived through a fluid model, and demonstrated via particle-in-cell simulations. The resulting efficiency is similar to single-frequency amplifiers, but, due to the beat-wave waveform of both the pump lasers and the amplified seed pulses, these amplifiers feature higher seed intensities with a shorter spike duration. Advantageously, these amplifiers also suffer less noise backscattering, because the total fluence is split between the different spectral components.
在通常的实现方式中，拉曼放大器只有一个泵浦载波频率。然而，当脉冲在时间上被压缩时，具有良好分离频率的脉冲也可以被拉曼放大。通过流体模型推导并通过粒子模拟验证，即使在高度非线性、泵浦耗尽的情况下，分频泵浦的放大仍然成立。所得到的效率与单频放大器相似，但由于泵浦激光器和放大种子脉冲的拍频波形，这些放大器具有更高的种子强度和更短的尖峰持续时间。有利的是，由于总通量被分配到不同的光谱分量之间，这些放大器受到的噪声背散射也较少。
