AI 中文总结
研究基于光子时间晶体的黑体辐射放大，通过研究电磁场的空间相关性和频谱，发现初始黑体辐射会周期性收敛到高斯相关和频谱，其幅度等逐渐增加，该渐近行为受PTC动量带结构控制，可用旋转波近似理解。
AI 中文摘要
时变介质光子学中最有趣的现象之一可能是光子时间晶体（PTC）中的光放大。然而，迄今为止的研究仅集中在基于PTC的相干光放大上。在这项工作中，我们从理论上研究了基于PTC的热辐射放大，特别是黑体辐射。由于热辐射固有的随机性，这种放大从根本上引人入胜，又因其普遍性而具有技术相关性。为简单起见，且考虑到传输线的实验相关性，我们考虑一维介质。为分析基于PTC的黑体辐射放大，我们研究了电磁场的空间相关性和空间频谱。我们表明，初始黑体辐射会周期性地收敛到高斯空间相关性和频谱，其幅度、相干长度以及空间和波数域纯度逐渐增加。我们进一步证明，这些渐近行为由PTC的动量带结构控制，并且可以通过对PTC中电磁场的伪厄米动力学使用旋转波近似来理解。
英文摘要
One of the most intriguing phenomena in time varying-media photonics is the amplification of light in a photonic time crystal (PTC). However, studies to date have focused exclusively on PTC-based amplification of coherent light. Here, we theoretically investigate the PTC-based amplification of thermal radiation, specifically blackbody radiation. Such amplification is not only fundamentally intriguing due to the thermal radiation's stochastic nature, but also technologically relevant because thermal radiation's ubiquity, which implies that its amplification generally accompanies that of coherent radiation. For simplicity, and due to the experimental relevance of PTC amplification in transmission lines, we consider amplification in a one-dimensional medium. To analyze the amplification of blackbody radiation in a PTC, we examine the electromagnetic fields' spatial correlations and spatial spectra. We show that the spatial spectra of initially blackbody radiation converge periodically toward Gaussian profiles with progressively increasing amplitudes, coherence lengths, and spatial- and wavenumber-domain purities. We demonstrate that these asymptotic behaviors are governed by the PTC momentum band structure and can be understood using a rotating-wave approximation for the pseudo-Hermitian dynamics of the electromagnetic field in a PTC. Beyond revealing the fundamental evolution of thermal radiation in time-varying media, our numerical framework provides a general approach for analyzing the dynamics of stochastic electromagnetic fields in PTCs and time-varying media, in general. The results also provide physical insight and practical guidance for the design of PTC-based amplifiers, where the concurrent amplification of parasitic thermal radiation may occur.
