180 Gbit/s Si₃N₄-waveguide coupled germanium photodetector with improved quantum efficiency

Petropoulos, Periklis (2021) 180 Gbit/s Si₃N₄-waveguide coupled germanium photodetector with improved quantum efficiency. Optics Letters, 46 (24), 6019-6022. (doi:10.1364/OL.438962).

Abstract

A high quantum efficiency (QE) and high-speed silicon nitride (Si₃N₄) waveguide coupled germanium-on-silicon photodetector (Ge-on-Si PD) is presented. The proposed device is fabricated in a commercial 90 nm silicon photonics process platform. By decreasing the spacing between the tapered Si₃N₄ waveguide and the bottom Si to 200 nm and the Si₃N₄ thickness to 300 nm, the QE is significantly improved. Although the theoretical responsivity can reach up to 0.92 A/W at 1550 nm, the measured value is calculated to be approximately 0.61 A/W. The maximum experimental responsivity is about 0.9 A/W at 1485 nm. The 3 dB optoelectrical bandwidth of up to 54 GHz is demonstrated at a −3.3V bias. Additionally, the 80, 90, 100, and 105 Gbit/s non-return-to-zero on-off-keying and the 150, 160, 170, and 180 Gbit/s four-level pulse amplitude modulation clear openings of the electrical eye diagrams are attained. Overall, the Si₃N₄-waveguide coupled Ge-on-Si PD in this work possesses higher QE and operates at the highest data rates reported so far.

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Contributors

Author: Periklis Petropoulos

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