Design and simulation of a waveguide-integrated GeSi modulator based on the Franz-Keldysh effect with a high-efficiency butt-coupling structure

We present a waveguide-integrated electro-absorption modulator utilizing GeSi alloy technology with a butt-coupling configuration. By introducing a poly-Si taper, the coupling efficiency of the modulator is maintained above 95% within the 1500-1600 nm wavelength range. The demonstrated device achieves a 3dB bandwidth of up to 197 GHz at the wavelength of 1550 nm, an extinction ratio of 5.32 dB, and an insertion loss of 2.68 dB. Additionally, the modulator exhibits excellent detection performance with a responsivity of 0.986 A/W.