Record 52.8 GHz 3-dB Bandwidth GeSn Photodiode Enabling 100 Gbps at 2 μm for Optical Interconnects

In this work, vertical mesa-structured GeSn Photodiodes (PDs) optimized for the 2 μm spectral window are demonstrated, address the critical demand for high-bandwidth receivers in next-generation optical interconnects. The device architecture, engineered through rigorous material and capacitance simulations, achieved a record-breaking 3-dB bandwidth of 52.8 GHz at -5 V bias—the highest reported for photodetectors operating in this wavelength regime—while maintaining an ultralow capacitance of 5.1 fF and a dark current of 32.1 μA. Notably, Demonstrating the first 100 Gbps NRZ transmission in the 2 μm band with a bit error rate (BER) of 4.72×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> at a signal-to-noise ratio (SNR) of 11.3 dB, and achieving 80 Gbps NRZ operation at a lower BER of 9.24×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> with 14.5 dB SNR. The demonstrated performance, combined with wafer-scale manufacturing compatibility, establishes GeSn PDs as a key enabling technology for high-capacity optical communication systems leveraging the emerging 2 μm window.