Magneto-optical (MO) effects have a pivotal role in modern photonic devices for light manipulation and sensing, but the study of these effects has so far been limited to the MO Faraday and Kerr effects. Conventional MO systems encounter considerable intrinsic losses, markedly hampering their ability to amplify the MO effects. Here we introduce a loss-enhanced MO effect to sublinearly amplify the frequency response of a non-Hermitian optical cavity under different background magnetic fields. This exceptional MO effect relies on an architecture of MO material embedded in a Fabry–Pérot cavity, accompanied by a polarization-dependent optical absorption, that is, linear dichroism, to construct a reconfigurable exceptional point. The experimental results show that two eigenmodes of the Fabry–Pérot cavity exhibit sublinear frequency splitting. By electrically reconfiguring the absorber, the eigenfrequency shift can be adaptively enhanced under different background magnetic fields. Using this effect, we demonstrate the detection of subtle magnetic field variations in a strong background, with the system’s response magnified by a factor exceeding 10 and sensitivity increased threefold compared with its conventional Hermitian counterpart. Our study leverages exceptional physics to study the MO effect and develops a new class of reconfigurable MO devices equipped with enhanced sensitivity for potential integration with photonic systems.

磁光 （MO） 效应在用于光操纵和传感的现代光子器件中起着举足轻重的作用，但到目前为止，对这些效应的研究仅限于 MO 法拉第和克尔效应。传统的 MO 系统遇到了相当大的内在损耗，明显阻碍了它们放大 MO 效应的能力。在这里，我们引入了一种损耗增强的 MO 效应，以亚线性放大不同背景磁场下非厄米特光腔的频率响应。这种特殊的 MO 效应依赖于嵌入法布里-佩罗腔中的 MO 材料结构，伴随着偏振依赖性的光吸收，即线性二色性，以构建一个可重构的异常点。实验结果表明，Fabry-Pérot 腔的两个特征模态表现出亚线性分频。通过对吸收器进行电气重新配置，可以在不同的背景磁场下自适应地增强特征频率偏移。利用这种效应，我们展示了在强背景下检测细微的磁场变化，与传统的埃尔米特同类产品相比，系统的响应放大了 10 倍以上，灵敏度提高了三倍。我们的研究利用卓越的物理学来研究 MO 效应，并开发了一类新的可重构 MO 器件，这些器件配备了增强的灵敏度，可与光子系统集成。