Thin-film Al0.30Ga0.70As (111) as a ‘flat’ source of high-purity orthogonally polarized entangled photons

Stich S, Sultanov V, Blaikie T, Shi Q, Wasilewski Z, Belkin MA, Chekhova M (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Optics Express Optical Society of America

Book Volume: 34

Pages Range: 1664-1673

Journal Issue: 2

DOI: 10.1364/OE.582010

Abstract

Flat-optics platforms offer new opportunities for the generation of entangled photons by relaxing traditional phase-matching constraints, enabling the use of a broader range of nonlinear materials. Among these, gallium arsenide and aluminum gallium arsenide stand out for their exceptionally high second-order nonlinearities, but their conventional orientation (001) has limited their applicability for photon-pair generation. By transitioning to crystals with (111) surface orientation, we overcome these limitations. We demonstrate a flat-optics-based telecom-range SPDC source using Al0.30Ga0.70As that achieves a high photon-pair generation rate per pump power and bandwidth of up to 0.24 Hz/mW/nm. The choice of 30% aluminum concentration allowed us to reduce pump absorption and photoluminescence background for photon pairs generation at telecom wavelengths by at least an order of magnitude compared to that of GaAs. The specific layer orientation facilitates the generation of orthogonally polarized entangled photons, a prerequisite for polarization-entangled states. Rather than directly probing entanglement, we observe the effect of hidden polarization. Our results highlight AlGaAs (111) as a promising platform for scalable quantum photonic sources and shed light on nonclassical polarization effects accessible through flat-optics engineering.

Involved external institutions

Technische Universität München (TUM)

Germany (DE) Max-Planck-Institut für die Physik des Lichts (MPL) / Max Planck Institute for the Science of Light

Germany (DE) University of Waterloo (UW)

Canada (CA)

How to cite

APA:

Stich, S., Sultanov, V., Blaikie, T., Shi, Q., Wasilewski, Z., Belkin, M.A., & Chekhova, M. (2026). Thin-film Al0.30Ga0.70As (111) as a ‘flat’ source of high-purity orthogonally polarized entangled photons. Optics Express, 34(2), 1664-1673. https://doi.org/10.1364/OE.582010

MLA:

Stich, Simon, et al. "Thin-film Al0.30Ga0.70As (111) as a ‘flat’ source of high-purity orthogonally polarized entangled photons." Optics Express 34.2 (2026): 1664-1673.

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