biostudies-literatureSkandalos IRCUK | Engineering and Physical Sciences Research Council (EPSRC)EC | EU Framework Programme for Research and Innovation H2020 | H2020 European Institute of Innovation and Technology (H2020 The European Institute of Innovation and Technology)82https://www.ebi.ac.uk/biostudies/studies/S-EPMC12046052biostudies-literatureUnknown4(1)The exponential growth of data-intensive artificial intelligence necessitates ultra-fast and energy efficient transceivers in data centres. Quantum-confined Stark effect (QCSE) modulators offer promising solutions, combining high-speed modulation with minimal footprint and superior energy efficiency. Here, we demonstrate a monolithically integrated O-band Ge/SiGe QCSE modulator operating at 100 Gb s^-1, seamlessly integrated with silicon nitride (SiN) waveguides on both silicon and silicon-on-insulator substrates. Our modulator achieves <1 dB coupling loss,  <63 fJ bit^-1 energy consumption, and  >5 dB static extinction ratio, while maintaining performance across a 20-80 °C temperature range. Leveraging CMOS-compatible fabrication processes, we incorporate multiple quanCommunications engineeringA 100 Gb s&lt;sup&gt;-1&lt;/sup&gt; quantum-confined Stark effect modulator monolithically integrated with silicon nitride on Si.PMC12046052EP/T028475/1871391EP/R003076/1Gardes FYZilkie ASkandalos IYu GBucio TDMastronardi LfalseA 100 Gb s&lt;sup&gt;-1&lt;/sup&gt; quantum-confined Stark effect modulator monolithically integrated with silicon nitride on Si.The exponential growth of data-intensive artificial intelligence necessitates ultra-fast and energy efficient transceivers in data centres. Quantum-confined Stark effect (QCSE) modulators offer promising solutions, combining high-speed modulation with minimal footprint and superior energy efficiency. Here, we demonstrate a monolithically integrated O-band Ge/SiGe QCSE modulator operating at 100 Gb s^-1, seamlessly integrated with silicon nitride (SiN) waveguides on both silicon and silicon-on-insulator substrates. Our modulator achieves <1 dB coupling loss,  <63 fJ bit^-1 energy consumption, and  >5 dB static extinction ratio, while maintaining performance across a 20-80 °C temperature range. Leveraging CMOS-compatible fabrication processes, we incorporate multiple quan2025-01-01T00:00:00Z2025 May2025-07-08T03:11:37.38Z2025-07-08T03:11:37.38ZS-EPMC120460524031249910.1038/s44172-025-00421-6