近日，德国卡尔斯鲁厄理工学院的X. Wang&P. Garg及其研究团队取得一项新进展。经过不懈努力，他们成功通过共振扩展光子时间晶体中的动量带隙。相关研究成果已于2024年11月12日在国际知名学术期刊《自然—光子学》上发表。

本研究表明，通过在共振材料中引入时间变化，可以显著扩大动量带隙，而所需的调制强度在当前已知的低损耗材料和实际可行的激光泵浦功率范围内即可实现。

这种共振可以源自材料的固有共振，也可以源自支持结构共振的适当空间结构化材料。这一概念已在共振体材料和光学超表面中得到了验证，为光子时间晶体的首次实验实现铺平了道路。

据悉，光子时间晶体的实现既是一个重大机遇，也伴随着相当大的挑战。其中最紧迫的可能是，需要在材料特性中实现相当强的调制强度，以产生明显的动量带隙。由于当前乃至未来可能的材料平台的调制强度往往较小，因此在光学领域实现这一明显的带隙要求极高。

附：英文原文

Title: Expanding momentum bandgaps in photonic time crystals through resonances

Author: Wang, X., Garg, P., Mirmoosa, M. S., Lamprianidis, A. G., Rockstuhl, C., Asadchy, V. S.

Issue&Volume: 2024-11-12

Abstract: The realization of photonic time crystals is a major opportunity but also comes with considerable challenges. The most pressing one, potentially, is the requirement for a substantial modulation strength in the material properties to create a noticeable momentum bandgap. Reaching that noticeable bandgap in optics is highly demanding with current, and possibly also future materials platforms because their modulation strength is small by tendency. Here we demonstrate that by introducing temporal variations in a resonant material, the momentum bandgap can be drastically expanded with modulation strengths in reach with known low-loss materials and realistic laser pump powers. The resonance can emerge from an intrinsic material resonance or a suitably spatially structured material supporting a structural resonance. Our concept is validated for resonant bulk media and optical metasurfaces and paves the way towards the first experimental realizations of photonic time crystals.

DOI: 10.1038/s41566-024-01563-3

Source: https://www.nature.com/articles/s41566-024-01563-3