Naval Research Laboratory, Washington, DC 20375-5346, USA.
Phys Rev E. 2017 May;95(5-1):053209. doi: 10.1103/PhysRevE.95.053209. Epub 2017 May 22.
An intense, short laser pulse incident on a transparent dielectric can excite electrons from the valence to the conduction band. As these electrons undergo scattering, both from phonons and ions, they emit bremsstrahlung. Here we present a theory of bremsstrahlung emission appropriate for the interaction of laser pulses with dielectrics. Simulations of the interaction, incorporating this theory, illustrate characteristics of the radiation (power, energy, and spectra) for arbitrary ratios of electron collision frequency to radiation frequency. The conversion efficiency of laser pulse energy into bremsstrahlung depends strongly on both the intensity and duration of the pulse, saturating at values of about 10^{-5}. Depending on whether the intensity is above or below the damage threshold of the material, the emission can originate either from the surface or the bulk of the dielectric, respectively. The bremsstrahlung emission may provide a broadband light source for diagnostics.
当强度高、持续时间短的激光脉冲入射到透明电介质上时，会将价带中的电子激发到导带中。这些电子在经历散射时，无论是来自声子还是离子，都会发射韧致辐射。在这里，我们提出了一种适用于激光脉冲与电介质相互作用的韧致辐射发射理论。对这种相互作用的模拟表明，辐射的特征（功率、能量和光谱）对于电子碰撞频率与辐射频率之比是任意的。激光脉冲能量向韧致辐射的转换效率强烈地取决于脉冲的强度和持续时间，其饱和值约为 10^{-5}。根据强度是高于还是低于材料的破坏阈值，发射可以分别来自电介质的表面或体。韧致辐射发射可能为诊断提供宽带光源。
