On-Chip Optical Power Monitor Using Periodically Interleaved P-N Junctions Integrated on a Silicon Waveguide

We investigate the photocurrent generation with surface-state absorption effect in a silicon waveguide integrated with periodically interleaved p-n junctions. Due to the high electric field (~5 × 10⁵ V/cm) and large depletion area coverage in the waveguide, our device can collect more photocurrent than regular p-i-n and p-n structures. The responsivity of our device is optical power dependent with a higher value at a lower power level. The measured 3-dB bandwidth of the frequency response is 11.5 GHz. Although its responsivity is low compared to that of III-V and Ge photodiodes, its simple fabrication and compatibility with all-silicon photonic devices makes it suitable as on-chip optical power monitors.