Pulse-Width-Modulation-Based Silicon Photonics Receiver with Readout Circuitries for On-chip Optical Power Monitoring

In this paper, a pulse-width-modulation (PWM)-based silicon photonics receiver for optical power monitoring that was realized using a 90-nm CMOS silicon-on-insulator (SOI) process is reported. By monitoring the DC or the AC power in the optical nodes and converting it into an electrical signal, large-scale photonic integrated circuits can acquire smartness and automation characteristics. The proposed PWM-based silicon photonics receiver can simply readout the optical power of target nodes without complex mixed-mode circuitries, such as analog-to-digital converters. The PWM receiver consists of a I–V amplifier, simple digital circuitries, free-running on-chip oscillators, and bias circuits. The receiver achieves a 10-nA detection limit, under a 1.5% detection error due to the quantization process of the PWM scheme. The receiver can operate as an on-chip optical power monitor for large-scale silicon-based photonic integrated circuits.