Giant enhancement of the transverse magneto-optical Kerr effect in etchless bismuth-substituted yttrium iron garnet empowered by quasi-bound states in the continuum

Abstract

Here, we propose an etchless bismuth-substituted yttrium iron garnet layer assisted by a one-dimensional resonant grating waveguide to enhance transverse magneto-optical Kerr effect (TMOKE) via the excitation of quasi-bound state in the continuum. The TMOKE amplitude can be tailored by manipulating the perturbation parameter, and it can reach as high as 1.978, approaching the theoretical maximum value of 2. Additionally, a single-mode temporal coupled-mode theory is employed to further reveal the underlying physical mechanism. It is found that TMOKE is strongly related to the line width of the quasi-BIC resonance and local field enhancement, which are pivotal factors in the design and optimization of photonic devices. As a potential application, we design and numerically demonstrate a refractive index sensor based on the resonantly enhanced TMOKE, with the optimal sensitivity of 110.66 nm/RIU and the corresponding maximum figure of merit of 299.3 RIU${}^{-1}$. Our work provides a simple and efficient approach for enhancing TMOKE based on an easy-to-fabricate platform, laying the groundwork for exploring and developing magneto-optical devices such as sensors, magnetic storage devices, and nonreciprocal photonic devices.

References in corpus (7)

• High-efficiency optical frequency mixing in an all-dielectric metasurface enabled by multiple bound states in the continuum
• Enhanced third-harmonic generation empowered by doubly degenerate quasi-bound states in the continuum
• Enhanced sum-frequency generation from etchless lithium niobate empowered by dual quasi-bound states in the continuum
• Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial
• Efficient photon-pair generation empowered by dual quasi-bound states in the continuum
• Enhancing Faraday and Kerr rotations based on toroidal dipole mode in an all-dielectric magneto-optical metasurface
• Extreme nonreciprocity in metasurfaces based on bound states in the continuum