64Gbps PAM4 Modulation for a Low Energy Si-Ge Waveguide APD with Distributed Bragg Reflectors

We demonstrate a low-voltage waveguide Si-Ge APD that integrates a distributed Bragg reflector (DBR). Quantum efficiency has been improved from 60% to 90% at 1550nm while still achieving a 25GHz bandwidth. The device under 64Gbps PAM4 modulation showed 30% increase in OMA, which enables 1.2dB improvement in receiver sensitivity.