An efficient vertical grating coupler design for arsenic trisulfide (As2S3) on silicon dioxide (SiO2) on lithium niobate (LN) is proposed, fabricated, and experimentally verified. We report 4 dB coupling efficiency per grating for vertical fiber coupling at a wavelength of 1550 nm with a 3 dB bandwidth of 40 nm using an aluminum reflector mirror between the LN and SiO2 interface. This coupler is the first step towards the demonstration of high-performance integrated photonic devices, which would simultaneously benefit from the acousto-optic properties of As2S3 and electro-optic and acoustic properties of LN. This hybrid platform is deemed to impact a broad range of applications such as imaging, ranging, and inertial sensing.
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