25 Gbps low-voltage waveguide Si-Ge avalanche photodiode

Silicon-germanium (Si-Ge)-based avalanche photodiodes (APDs) have shown a significant improvement in receiver sensitivity compared to their III-V counterparts due to the superior impact ionization property of silicon. However, conventional Si-Ge APDs typically operate at high voltages and low speed, limiting the application of this technology to data communication. In this paper, we present a waveguide Si-Ge avalanche photodiode using a thin silicon multiplication region with a breakdown voltage of -10 V, a speed of 25 GHz, and a gain-bandwidth product (GBP) of 276 GHz. At 1550 nm, sensitivities of -25 dBm and -16 dBm are achieved at 12.5 Gbps and 25 Gbps, respectively. This design will enable implementation of Si-Ge APDs for optical interconnects in data centers and high-performance computers, allowing significant reductions in aggregate system laser power (and therefore cost). (C) 2016 Optical Society of America