High-Efficiency,Large Bandwidth Grating Coupler Based on Lithium Niobate Thin Film(Invited)
This study proposes a large bandwidth two-dimensional grating coupler based on the lithium niobate platform.By introducing a lithium niobate crystal comprising a photoelectric material as the platform,a silicon triangle structure is adopted,and based on the effective medium theory,the transverse width of each triangle is changed along the direction of light propagation.A low refractive index oxide buffer layer is introduced between the silicon grating coupler and the bottom of lithium niobate thin film(LNTF)waveguide.A vertical grating coupler with a coupling efficiency of 60.8%and a 1 dB bandwidth of 102 nm is obtained at a wavelength of 1550 nm.
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