Deterministic positioning of circular Bragg gratings using atomic force lithography for high-performance quantum dot light sources

Sai Abhishikth Dhurjati; Moritz Langer; Yared G. Zena; Ahmad Rahimi; Liesa Raith; Martin Bauer; Frank H. P. Fitzek; Riccardo Bassoli; Caspar Hopfmann

arXiv · 2605.03672

Deterministic positioning of circular Bragg gratings using atomic force lithography for high-performance quantum dot light sources

Sai Abhishikth Dhurjati·Moritz Langer·Yared G. Zena·Ahmad Rahimi·Liesa Raith·Martin Bauer·Frank H. P. Fitzek·Riccardo Bassoli·Caspar Hopfmann

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Abstract

Semiconductor quantum dots (QDs) grown by molecular beam epitaxy are excellent quantum emitters, but their random spatial distribution hinders deterministic coupling to optical microcavities. We demonstrate a room-temperature atomic force microscopy (AFM)-assisted nano-oxidation lithography technique enabling QD positioning with a radial displacement of $51(28)$ nm. Free-standing asymmetric circular Bragg gratings incorporating AFM-positioned GaAs QDs exhibit a $245$-fold photoluminescence enhancement and fine-structure splitting (FSS) comparable to bulk QDs. Polarization-resolved spectroscopy and finite-difference time-domain simulations show robust emission for displacements up to $50$ nm (Stokes parameter $\lvert S \rvert < 0.05$ ). The devices display stable FSS and polarization imbalance below $5 \, \%$ , confirming precise, reproducible alignment and potential for high fidelity devices. This scalable approach enables deterministic integration of high-performance QDs with photonic cavities, advancing practical quantum light sources for quantum information technologies.

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Sai Abhishikth Dhurjati, Moritz Langer, Yared G. Zena, Ahmad Rahimi, Liesa Raith, Martin Bauer, Frank H. P. Fitzek, Riccardo Bassoli, Caspar Hopfmann. 2026-05-05. Deterministic positioning of circular Bragg gratings using atomic force lithography for high-performance quantum dot light sources. https://arxiv.org/abs/2605.03672

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