Design and Characterization of Current-Assisted Photonic Demodulators in 0.18- CMOS Technology

We report on the design of a current-assisted photonic demodulator (CAPD) using standard 0.18-μm complementary metal-oxide-semiconductor technology and its electrooptical characterization. The device can perform both light detection and demodulation in the charge domain, owing to a drift field generated in the silicon substrate by a majority carrier flow. Minimum-sized 10 × 10 μm² CAPDs exhibit a direct-current charge-transfer efficiency larger than 80% (corresponding to demodulation contrast larger than 40% under sine-wave modulation) at the modest power consumption of 10 μW and a 3-dB bandwidth of >; 45 MHz. An excellent linearity value with an error lower than 0.11% is obtained in phase measurements. CAPDs with optimized modulation electrode geometries are finally designed, aiming at an improved contrast-versus-power tradeoff.