High efficiency and responsivity universal silicon modulator and detector for the O-band

We report an O-band all-silicon microring resonator that employs an L-shaped depletion-type PN junction to realize both high-speed modulation and high-sensitivity photodetection within the same active region. For modulation, the device achieves a 55 GHz electro-optic 3-dB bandwidth and a modulation efficiency of 4.2 V·mm. For photodetection, a peak responsivity of 0.97 A/W is achieved at -5.9 V in avalanche mode with photon-assisted tunneling (PAT) under an on-chip input optical power of -6.25 dBm, while an opto-electronic 3-dB bandwidth of 25 GHz is obtained at a bandwidth-favorable bias of -5.5 V. We further discuss the trade-off among modulation efficiency, responsivity, and bandwidth and its impact on operating-point selection and system-level link budget. The results show that this universal device achieves performance comparable to dedicated silicon microring modulators and photodetectors, while significantly reducing the number of device types and area required in silicon transceivers, thereby providing a promising building block for high-bandwidth-density wavelength-division multiplexing links and programmable photonic integrated circuits.