Two-dimensional grating coupler on an X-cut lithium niobate thin-film

Bin Chen, Ziliang Ruan, Jinyao Hu, Jingyi Wang, Chao Lu, Alan Pak Tao Lau, Changjian Guo, Kaixuan Chen, Pengxin Chen, Liu Liu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

3 Citations (Scopus)


A two-dimensional grating coupler for coupling light between a standard single-mode fiber and ridge waveguides on an X-cut lithium niobate thin-film is designed and demonstrated. Using circular holes for grating cells, simulated coupling losses reach −3.88 dB at 1550 nm and −5.78 dB at 1563 nm with 1-dB bandwidths of 49 nm and 45 nm for P-polarized and S-polarized light inputs, respectively. Experimentally, peak coupling losses of −5.13 dB at 1561 nm and −7.6 dB at 1568 nm are obtained for P-polarized and S-polarized light inputs, respectively, and corresponding 1 dB bandwidths are about 30 nm. An approach to improve the coupling performance of the grating coupler is also proposed using two crossing ellipses as grating cells as well as a bottom metal reflector. The coupling loss and the polarization dependent loss are decreased to around −3.4 dB and 0.44 dB, respectively.

Original languageEnglish
Pages (from-to)1289-1295
Number of pages7
JournalOptics Express
Issue number2
Publication statusPublished - 18 Jan 2021

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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