This STW funded project investigates the feasibility of high-speed optocouplers in traditional CMOS technology, which is a step towards monolithic photonic-electronic chips. Major challenges are in achieving high energy efficiency and high data bandwidths simultaneously. This requires the development of LEDs and photodetectors with a significant overlap in the spectral distribution of light emission and photodetection. We will develop various emission and detection mechanisms yielding a blue shift respectively a red shift compared to conventional LEDs and photodetectors, while still achieving high data rates. Experimental validation and device benchmarking will be done as well. Another challenge is in modelling silicon based LEDs and photodetectors in a circuit-designer-friendly manner. This work is in close cooperation with the IC-design group, NXP Semiconductors, and Delft University of Technology.