Bofeng Zhu, Guobin Ren, Yixiao Gao, Haisu Li, Beilei Wu, and Shuisheng Jian
In this Letter, we show that a hexagonal boron nitride (h-BN) slot waveguide can achieve strong field enhancement and light confinement in a slot region and a giant gradient force between h-BN slabs. Excellent agreement between simulations and results from an analytical model is observed. In a two-dimensional case, a field enhancement ratio near 60, a power confinement ratio of 80%, and a gradient force over −8.5 nN/μm×mW−8.5 nN/μm×mW have been achieved, which are much higher than the slot waveguide based on artificial hyperbolic metamaterials. The gradient force and power confinement ratio in a three-dimensional slot waveguide structure are also studied. A gradient force of −1.2 nN/mW−1.2 nN/mW and a power confinement ratio of 50% have been obtained. The h-BN slot waveguide may have potential in particle manipulation.