Liu Na, Zhao Jia, Du Liuge, Niu Chuanning, Lin Xiao, Wang Zuojia, Li Xun
Opt Lett. 2019 Jun 15;44(12):3050-3053. doi: 10.1364/OL.44.003050.
Enhancing nonreciprocal light-matter interaction at subwavelength scales has attracted enormous attention due to high demand for compact optical isolators. Here, we propose a significant enhancement of the magneto-optical effect in low-biased gyromagnetic media via photonic doping. Magnetic particles immersed in a gyrotropy-near-zero medium act as dopants that largely modify the macroscopic gyromagnetic effects as well as the gyroelectric ones. Around the resonance frequency, the gyromagnetic activity is largely increased and even exceeds unity, thus providing a photonic band in which the wavenumber of one circularly polarized wave becomes purely imaginary. The sign of gyromagnetic activity flips at two chiral modes, and an equivalent switching of the external bias is revealed. A proof-of-concept low-biased planar isolator is designed with a thickness of only 1/28 wavelength and a degree of isolation achieving as high as 0.94. This methodology is robust against disturbance of the biased magnetic field and can be flexibly extended to other frequencies, thus offering a promising platform to achieve giant optical isolation with infinitesimally intrinsic magneto-optical effects and reduced sizes.
由于对紧凑型光学隔离器的高需求，增强亚波长尺度下的非互易光与物质相互作用已引起了极大关注。在此，我们提出通过光子掺杂显著增强低偏置旋磁介质中的磁光效应。浸没在近零旋光性介质中的磁性粒子充当掺杂剂，极大地改变了宏观旋磁效应以及旋电效应。在共振频率附近，旋磁活性大幅增加甚至超过1，从而提供了一个光子带，其中一个圆偏振波的波数变为纯虚数。旋磁活性的符号在两个手征模式处翻转，揭示了外部偏置的等效切换。设计了一个概念验证的低偏置平面隔离器，其厚度仅为1/28波长，隔离度高达0.94。该方法对偏置磁场的干扰具有鲁棒性，并且可以灵活扩展到其他频率，从而为实现具有极小固有磁光效应和减小尺寸的巨大光学隔离提供了一个有前景的平台。
