时间切换洛伦兹介质中的静态到动态场转换
Static-to-dynamic field conversion in a temporally switched Lorentz medium
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中文总结 AI 辅助
本研究探讨时间切换洛伦兹介质中静态电场向动态辐射的转换，通过拉普拉斯域解析求解，揭示了材料色散与记忆对瞬态场生成及演化的关键作用。
中文摘要 AI 辅助
我们研究了在初始施加静电场的洛伦兹介质中，经时间切换后的静态到动态电磁场转换。振荡强度的突然变化使材料偏离其初始平衡状态，而极化则保留了对切换前状态的记忆，并作为由此产生的瞬态场的源。我们在拉普拉斯域中构建了相应的初值问题，并根据有限洛伦兹板的极点推导了所生成场的解析表达式。与无色散情况相比，材料色散产生了更丰富的模态结构，包括一系列板模极点，这些极点向与洛伦兹极化动力学相关的奇点累积。我们进一步表明，材料记忆控制着瞬态的最早阶段，产生平滑的场起始，并通过高频介电常数设定最早传播扰动的速度。由于时间切换产生宽带频谱内容，瞬态场采样了切换后材料响应的正介电常数、近零介电常数和负介电常数区域，导致空间场分布出现质的差异。这些结果揭示了材料色散和记忆如何从根本上塑造从初始静态电磁状态产生的辐射的生成与演化。
英文摘要
We investigate static-to-dynamic electromagnetic field conversion in a temporally switched Lorentz medium initially subjected to an electrostatic field. An abrupt change of the oscillator strength drives the material away from its initial equilibrium, while the polarization retains memory of the pre-switch state and acts as the source of the resulting transient. We formulate the resulting initial-value problem in the Laplace domain and derive an analytical representation of the generated field in terms of the poles of the finite Lorentz slab. Material dispersion gives rise to a richer modal structure than in the nondispersive case, including families of slab-mode poles that accumulate toward the singularities associated with the Lorentz polarization dynamics. We further show that material memory governs the earliest stage of the transient, producing a smooth field onset and setting the velocity of the earliest propagating disturbance through the high-frequency permittivity. Because the temporal switch generates broadband spectral content, the transient samples positive-, near-zero-, and negative-permittivity regions of the post-switch material response, leading to qualitatively different spatial field distributions. These results reveal how material dispersion and memory fundamentally shape the generation and evolution of radiation produced from an initially static electromagnetic state.
发表机构
- University of Delaware（特拉华大学）
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