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arXiv · 2206.07971

Efficient Second Harmonic Generation from Silicon Slotted Nanocubes with Bound States in the Continuum

C. Fang·Q. Yang·Q. Yuan·L. Gu·X. Gan·Y. Shao·Y. Liu·G. Han·Y. Hao
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Abstract

Optical materials with centrosymmetry, such as silicon and germanium, are unfortunately absent of second-order nonlinear optical responses, hindering their developments in efficient nonlinear optical devices. Here, a design with an array of slotted nanocubes is proposed to realize remarkable second harmonic generation (SHG) from the centrosymmetric silicon, which takes advantage of enlarged surface second-order nonlinearity, strengthened electric field over the surface of the air-slot, as well as the resonance enhancement by the bound states in the continuum. Compared with that from the array of silicon nanocubes without air-slots, SHG from the slotted nanocube array is improved by more than two orders of magnitude. The experimentally measured SHG efficiency of the silicon slotted nanocube array is high as 1.8*10^-4 W^-1, which is expected to be further engineered by modifying the air-slot geometries. Our result could provide a new strategy to expand nonlinear optical effects and devices of centrosymmetric materials.

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C. Fang, Q. Yang, Q. Yuan, L. Gu, X. Gan, Y. Shao, Y. Liu, G. Han, Y. Hao. 2022-06-16. Efficient Second Harmonic Generation from Silicon Slotted Nanocubes with Bound States in the Continuum. https://doi.org/10.1002/lpor.202100498

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