56 Gbps high-speed Ge electro-absorption modulator

A high-speed evanescent-coupled Ge waveguide electro-absorption modulator (EAM) with simple fabrication processes was realized on a silicon-on-insulator platform with a 220 nm top Si layer. Selectively grown Ge with a triangle shape was directly used for Ge waveguides of the EAM. An asymmetric p-i-n junction was designed in the Ge waveguide to provide a strong electric field for Franz-Keldysh effect. The insertion loss of the Ge EAM was 6.2 dB at 1610 nm. The EAM showed the high electro-optic bandwidth of 36 GHz at -1 V. Clear open 56 Gbps eye diagrams were observed at 1610 nm with a dynamic extinction ratio of 2.7 dB and dynamic power consumption of 45 fJ/bit for voltage swing of 3V(pp). (C) 2020 Chinese Laser Press