All-Silicon Waveguide Photodetection for Low-Bias Power Monitoring and 20-km 28-Gb/s NRZ-OOK Signal Transmission

We investigate the detection characteristics of a vertical p-n junction embedded waveguide in the low-gain region and strong avalanche gain region. Due to the “L” shape p-n junction and relatively high doping concentration, the photon absorption is enhanced and the working bias is reduced. The detection has linear response to input power in a wide dynamic range and continuous response to wavelength throughout C+L bands. We obtain a responsivity of 0.54 A/W, a 3-dB OE bandwidth of 26 GHz and a gain-bandwidth product of 28 THz at the bias of -9 V in the proposed device. Up to 28-Gb/s NRZ-OOK signal is successfully modulated and detected in an all-silicon scheme in up to 20-km optical fiber transmission link. We believe the proposed device has the potential for applications in integrated power monitors and all-silicon transceivers.