Chen S, Rever M, Zhang P, Theobald W, Umstadter D
Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Oct;74(4 Pt 2):046406. doi: 10.1103/PhysRevE.74.046406. Epub 2006 Oct 18.
A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I = 1.3 x 10(18) W cm(-2), lambda = 1.05 microm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8-100 nm when the pump laser power is increased from 0.45-2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump power of 2.4 TW. The experimental cross-phase modulated spectra compared well with theoretical calculations. Applications to generation of high-power single-cycle pulses are also discussed.
报道了一种非线性光学现象——相对论性交叉相位调制。实验观察到一束相对论强度的光束（I = 1.3×10¹⁸ W cm⁻²，λ = 1.05微米）在等离子体中引起同向传播的低强度光束的相位调制。后一束光是在前一束光经历受激拉曼前向散射不稳定性时产生的。当泵浦激光功率从0.45 - 2.4太瓦增加时，发现拉曼卫星峰的带宽从3.8 - 100纳米变宽。在2.4太瓦的泵浦功率下，观察到相对论性交叉相位调制的一个特征，即拉曼信号的不对称光谱展宽。实验得到的交叉相位调制光谱与理论计算结果吻合良好。还讨论了其在高功率单周期脉冲产生方面的应用。
