Work

Lateral Quantum-Confined Stark Effect for Integrated Quantum Dot Electroabsorption Modulators

Year: 2025

Type: article

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$\mu$m In$_{x}$Ga$_{1-x}$As/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 In$_{x}$Ga$_{1-x}$As/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.

Source: IEEE Journal of Selected Topics in Quantum Electronics

DOI: 10.1109/jstqe.2025.3552024

Authors: Tommy Murphy, Christopher A. Broderick, Frank H. Peters, Eoin P. O'Reilly

Institutions: University College Cork, Tyndall National Institute

Language: English

Topic: Semiconductor Quantum Structures and Devices

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,645

Funder: Research Ireland