Chiral modes and directional lasing at exceptional points
Chiral modes and directional lasing at exceptional points
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DOI：
10.1073/pnas.1603318113
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发表时间：
2016-06-21
影响因子：
11.1
通讯作者：
Yang, Lan
中科院分区：
文献类型：
--
作者：
Peng, Bo;Ozdemir, Sahin Kaya;Yang, Lan
控制微结构和纳米结构中的光的发射和流动对于片上信息处理至关重要。在这里，我们展示了如何施加一个强大的手征性和可切换的方向的光传播的光学系统，通过引导它到一个例外点（EP）-简并普遍发生在所有开放的物理系统时，两个本征值和相应的本征态合并。在我们的实验与光纤耦合的回音壁模式（WGM）谐振腔，我们动态地控制谐振腔模式的手征性和发射方向的WGM微激光器在附近的EP：远离EP，谐振腔模式是非手性和激光发射是双向的。当系统接近EP时，模式变成手性的并且允许单向发射，使得通过从一个EP转变到另一个EP，发射方向可以完全反转。我们的研究结果揭示了非厄米物理学的一个非常违反直觉的特征，为芯片上的手征光子学铺平了道路。
Controlling the emission and the flow of light in micro-and nanostructures is crucial for on-chip information processing. Here we show how to impose a strong chirality and a switchable direction of light propagation in an optical system by steering it to an exceptional point (EP)-a degeneracy universally occurring in all open physical systems when two eigenvalues and the corresponding eigenstates coalesce. In our experiments with a fiber-coupled whispering-gallery-mode (WGM) resonator, we dynamically control the chirality of resonator modes and the emission direction of a WGM microlaser in the vicinity of an EP: Away from the EPs, the resonator modes are nonchiral and laser emission is bidirectional. As the system approaches an EP, the modes become chiral and allow unidirectional emission such that by transiting from one EP to another one the direction of emission can be completely reversed. Our results exemplify a very counterintuitive feature of non-Hermitian physics that paves the way to chiral photonics on a chip.