AI 中文总结
该研究制备了非对称高Q空心微泡谐振器，发现其特定模式存在定向发射，揭示变形诱导高阶模式泄漏为定向辐射机制，为三维非对称回音壁腔光传输研究提供了高Q平台。
AI 中文摘要
具有旋转对称性破缺的回音壁模式（WGM）谐振器展现出传统对称腔中通常不存在的现象，包括定向发射。尽管这类效应已在固体谐振器和平面谐振器中得到广泛研究，但在空心三维腔中仍未被充分探索，空心腔的光学限制因薄壁几何结构而发生根本改变。在此，我们通过微泡形成过程中的各向异性膨胀，展示了非对称二氧化硅微泡谐振器的可控制备。X射线断层扫描证实了所得三维几何结构，并使我们能够定量表征腔的变形。尽管存在旋转对称性破缺，这些谐振器在适度变形下仍保持负载品质因数（Q值）超过10^5的回音壁模式。光学表征表明，仅特定共振模式表现出定向发射，而相邻模式仍保持传统的各向同性行为。二维数值模拟重现了观测到的发射特性，并表明变形诱导的高阶模式泄漏是定向辐射的合理机制。这些结果确立了非对称空心微泡谐振器作为研究三维非对称回音壁腔中光传输的平台，同时保留了光子学应用所需的高Q性能。
英文摘要
Whispering gallery mode (WGM) resonators with broken rotational symmetry exhibit phenomena that are generally absent in conventional symmetric cavities, including directional emission. While such effects have been extensively investigated in solid and planar resonators, they remain largely unexplored in hollow, three-dimensional cavities, where optical confinement is fundamentally altered by the thin wall geometry. Here, we demonstrate controlled fabrication of asymmetric silica microbubble resonators through anisotropic expansion during the microbubble formation process. X-ray tomography confirms the resulting three-dimensional geometry and allows us to quantitatively characterize the cavity deformation. Despite the broken rotational symmetry, the resonators maintain whispering gallery modes with high loaded Q-factors exceeding $10^5$ for moderate deformations. Optical characterization reveals that only certain resonances exhibit directional emission, whereas neighboring modes retain conventional isotropic behavior. Two-dimensional numerical simulations reproduce the observed emission characteristics and indicate that deformation-induced leakage of higher-order modes provides a plausible mechanism for the directional radiation. These results establish asymmetric hollow microbubble resonators as a platform for investigating light transport in three-dimensional asymmetric whispering gallery cavities while preserving the high-Q performance required for photonics applications.
Comments13 pages, 8 figures
