Journal of East China Normal University(Natural Science) ›› 2024, Vol. 2024 ›› Issue (3): 113-120.doi: 10.3969/j.issn.1000-5641.2024.03.012

• Atomic,Molecular, and Optical Physics • Previous Articles    

Research on optimization of the coupling efficiency of near-infrared lithium niobate grating coupler

Siqi LIU1, Minni QU2, Wei XIE1,*()   

  1. 1. State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
    2. Center for Advanced Electronic Materials and Devices, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, 200240, China
  • Received:2023-02-24 Online:2024-05-25 Published:2024-05-25
  • Contact: Wei XIE E-mail:wxie@phy.ecnu.edu.cn

Abstract:

We propose an efficient grating coupler design scheme based on a lithium niobate guided mode structure and its optimized optical excitation configuration. The coupling effect of the grating coupler is numerically analysed using the finite time domain difference algorithm. We study the effects of the grating period, grating duty ratio, silica isolation layer thickness, polarization and angle of incident light on the coupling efficiency of the grating. The spatial light propagation electric field images are simulated for resonant and non-resonant wavelengths. The results show that with a grating period of 650 nm, a grating duty cycle of 0.3 and an etching depth of 130 nm, an optimised grating coupling efficiency of ~38% can be obtained using TM(transverse magnetic) polarised light incident along the grating normal angle of 17°, thus effectively coupling spatial light into the lithium niobate subwavelength waveguide film. This is of great reference value for the design and application performance of LiNbO3 micro-nano grating couplers.

Key words: lithium niobate film, guided mode resonance, grating coupler, coupling efficiency

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