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arXiv · 2607.02902

Demonstration and Design of Uni-Directional and Ultra-Low Threshold Hybrid Quantum Dot III-V/Si Micro-Ring Laser

Xucheng Yang·Yingtao Hu·Antoine Descos·Yuan Yuan·Bassem Tossoun·Geza Kurczveil·Yatiraj Ramanujam·Jonathan Wierer·Raymond G. Beausoleil·Di Liang·Stanley Cheung
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Abstract

Micro-ring lasers (MRLs) are attractive light sources for energy-efficient optical interconnects, but their intrinsic directional bistability leads to unpredictable clockwise/counter-clockwise emission. We demonstrate stable unidirectional emission in hybrid quantum-dot (QD) III-V/Si MRLs using passive reflective feedback integrated on the bus waveguide, leaving the ring cavity unperturbed. Three reflector architectures - Y-splitter loop mirrors, adiabatic Y-splitter loop mirrors, and distributed Bragg reflectors (DBRs) - are benchmarked against a reflector-free bidirectional baseline through combined experiment and coupled-mode-theory rate-equation modeling. All designs preserve ultra-low thresholds of 0.79-1.12 mA (112-158 A/cm^2, roughly an order of magnitude below prior quantum-well unidirectional ring lasers) while enhancing single-facet output power and wall-plug efficiency, with directional isolation up to 27.65 dB for the DBR. The reflectors impose no penalty on the 4-5 GHz modulation bandwidth or its thermal robustness, establishing passive external feedback as a practical route to unidirectional QD MRLs for DWDM-scale optical interconnects.

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Xucheng Yang, Yingtao Hu, Antoine Descos, Yuan Yuan, Bassem Tossoun, Geza Kurczveil, Yatiraj Ramanujam, Jonathan Wierer, Raymond G. Beausoleil, Di Liang, Stanley Cheung. 2026-07-03. Demonstration and Design of Uni-Directional and Ultra-Low Threshold Hybrid Quantum Dot III-V/Si Micro-Ring Laser. https://arxiv.org/abs/2607.02902

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