Broadband and high efficiency apodized grating coupler via multi-wavelength mode matching

Abstract The coupling bandwidth of apodized grating coupler (AGC) focused on single-wavelength designs is relatively narrow, which leads to their limitation in high-capacity communication. To address this challenge, we adopted a multi-wavelength mode matching method to design AGC, which enhance both phase and mode-field matching at multiple wavelengths. On the Silicon-On-Insulator (SOI) platform, compared with single-wavelength AGC, the 3 dB bandwidth of multi-wavelength AGC increases from 60 to 88 nm, and the coupling loss decreases from 1.74 to1.3 dB. Additionally, on the silicon nitride (Si 3 N 4 ) platform. compared with single-wavelength AGC, the 1 dB bandwidth of multi-wavelength AGC increases from 39 to 79 nm, and the coupling loss decreases from 2.7 to 2.2 dB, and with a great 3 dB bandwidth of 140 nm, which represents the largest bandwidth obtained on the Si 3 N 4 platform without adding complex structures. These results demonstrate the effectiveness of the multi-wavelength mode matching method in designing AGCs for improving bandwidth and coupling efficiency in communication systems.