发表机构
Advanced Science Research Center, City University of New York; Graduate Center, City University of New York（纽约城市大学高级科学研究中心; 纽约城市大学研究生中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文实验证明，通过复数频率激发无源高折射率介电球，可模拟增益材料，实现前向散射26dB抑制且保持其他方向强散射，为增强无源物体散射控制提供新途径。
AI 中文摘要
光学定理规定，物体在前向方向上的波散射与激发中消逝的总功率成正比。对于无源物体，这一关系是直观概念的副产品，即散射和吸收必然产生阴影，而零前向散射（即无阴影）只有在物体完全透明（既不散射也不吸收）时才能实现。原则上，具有增益的材料可用于抑制前向散射，同时在其他方向保持较大的散射特征。然而，实现足够的光学增益具有挑战性，且其固有地导致不稳定性和非线性。在此，我们通过实验展示了利用复数频率信号激发无源高折射率介电球体，该信号被定制为模拟材料增益的存在，从而实现了无阴影散射。与最优单色激发相比，我们实现了前向散射高达26dB的抑制，同时在其他方向保持了强散射。更广泛地，我们的结果展示了复数频率如何提供一种自然途径来增强对无源物体散射特征的控制，对一系列光子学应用具有重要意义。
英文摘要
The optical theorem dictates that the wave scattering of an object in the forward direction is proportional to the total power extinguished from the excitation. For passive objects, this relationship is a by-product of the intuitive notion that scattering and absorption necessarily create shadows, and that zero forward scattering, i.e., no shadow, can only be obtained if the object is fully transparent, i.e., it neither scatters nor absorbs. Materials with gain can be in principle leveraged to suppress forward scattering while preserving a large scattering signature in other directions. However, sufficient optical gain is challenging to realize, and it inherently leads to instabilities and nonlinearities. Here, we experimentally demonstrate shadow-free \ scattering from a passive high-index dielectric sphere by exciting it with a complex frequency signal tailored to mimic the presence of material gain. We achieve as much as 26dB suppression of the forward scattering when compared with optimal monochromatic excitations, while preserving strong scattering in other directions. More broadly, our results demonstrate how complex frequencies offer a natural pathway to enhance control over the scattering signature of passive objects, with implications for a range of photonic applications.
