Multimode photodiode on germanium-on-silicon for TE ₀ ,TE ₁ , and TE ₂ modes

With the development of integrated optics, mode-division multiplexing (MDM) has drawn lots of attention. In this Letter, we demonstrate a multimode photodiode (PD) on germanium-on-silicon (GeSi) for TE₀ TE₁, and TE₂ modes. The width and length of the germanium are 8 µm and 10 µm, respectively. The responsivities of the TE₀, TE₁, and TE₂ modes are 0.93 A/W, 1.05 A/W, and 0.91 A/W, respectively. An on-chip inductor and U-shaped electrode are adopted to enhance the bandwidth of the multimode PD. The 3-dB OE bandwidths of the TE₀, TE₁, and TE₂ modes are 55.5 GHz, 55.2 GHz, and 53.3 GHz, respectively. 200 Gb/s PAM4 modulation is successfully realized for the three modes. This multimode PD can be used in a MDM photonic neural network (PNN) accelerator and other optical multimode systems.