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

doi:10.3969/j.issn.1000-5641.2024.03.012

Abstract

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

CLC Number:

O439

Siqi LIU, Minni QU, Wei XIE. Research on optimization of the coupling efficiency of near-infrared lithium niobate grating coupler[J]. Journal of East China Normal University(Natural Science), 2024, 2024(3): 113-120.

Figures/Tables 5

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