Lateral quantum-confined stark effect for integrated quantum dot electroabsorption modulators
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Date
2025
Authors
Murphy, Tommy
Broderick, Christopher A.
Peters, Frank H.
O'Reilly, Eoin P.
Journal Title
Journal ISSN
Volume Title
Publisher
Institute of Electrical and Electronics Engineers Inc.
Published Version
Abstract
Advances in III-V on Si quantum dot (QD) growth have enabled monolithic integration of high-performance electrically-pumped lasers on Si, as an enabling component for Si photonics. Another critical component is the electroabsorption modulator (EAM), which exploits the quantum-confined Stark effect (QCSE) to achieve high-speed modulation of laser signals. Conventional quantum well (QW) EAMs exploit a "vertical"QCSE via top and bottom electrical contacts. Rapid advancements in planar photonic integrated circuit technology motivate development of laterally-contacted EAMs, which offer benefits including reduced parasitic capacitance. The QCSE cannot be achieved via a lateral field in a QW, but can in a QD due to the three-dimensional carrier confinement. Here, theoretical analysis of the lateral-field QCSE in 1.3 μm InxGa1-xAs/GaAs QDs is undertaken. Comparing the QCSE produced by vertical and lateral electric fields for realistic QD morphology a robust lateral-field QCSE is demonstrated, with the optical absorption edge redshifting more rapidly vs. field strength than in a conventional QW-EAM. It is shown that lateral-field QD-EAM performance is expected to be strongly sensitive to the spectral linewidth of the band edge absorption, and can also depend upon the in-plane orientation of the lateral electric field. The impact of QD morphology - the base shape, aspect ratio and composition profile - is also quantified. It is demonstrated that InxGa1-xAs/GaAs QDs possessing high aspect ratios and low absorption linewidths are well-suited to develop lateral-field QD-EAMs. This suggests leveraging III-V on Si epitaxy to integrate EAMs with lasers or single-photon sources to realize high-speed Si photonic integrated circuits for applications in datacomms and linear optical quantum computing.
Description
Keywords
Electroabsorption modulators (EAMs) , Integrated photonics , Quantum dots , Quantum-confined Stark effect (QCSE) , Silicon photonics
Citation
Murphy, T., Broderick, C. A., Peters, F. H. and O'Reilly, E. P. (2025) 'Lateral quantum-confined stark effect for integrated quantum dot electroabsorption modulators', IEEE Journal of Selected Topics in Quantum Electronics, 31(5), 1900310 (10pp). https://doi.org/10.1109/JSTQE.2025.3552024