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arXiv · 2608.00833

Efficient Mode Conversion at 1064 nm via Bilayer Inverse Taper on Thin-Film Lithium Niobate

Ruidong Xue·Jobayer Hossain·Joshua Arnold·Jiuyi Zhang·Xiaofeng Zhu·Marco Moller de Freitas·Christopher J. Cullen·Shouyuan Shi·Peng Yao·Timothy Creazzo·Dennis Prather
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Abstract

Efficient fiber-to-chip coupling remains challenging for thin-film lithium niobate (TFLN) devices operating at 1064 nm. Here, we fabricate and characterize an on-chip optical mode converter based on a bilayer inverse taper. The proposed structure demonstrated a coupling loss of 1.9 dB per facet for the TE mode, with a 1 dB bandwidth spanning 1055--1085 nm. The polarization-dependent alignment tolerance was measured along the lateral and vertical directions. Theoretical and simulation analyses indicate that, when using a lensed fiber with a mode field diameter of 2.5 $\mu$m, the coupling loss can be reduced to as low as 0.48 dB per facet. These results demonstrate the feasibility of providing a high-efficiency solution for on-chip optical coupling at 1064 nm.

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Ruidong Xue, Jobayer Hossain, Joshua Arnold, Jiuyi Zhang, Xiaofeng Zhu, Marco Moller de Freitas, Christopher J. Cullen, Shouyuan Shi, Peng Yao, Timothy Creazzo, Dennis Prather. 2026-08-01. Efficient Mode Conversion at 1064 nm via Bilayer Inverse Taper on Thin-Film Lithium Niobate. https://arxiv.org/abs/2608.00833

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