Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optics Letters

Dispersion-free photon-pair generation enabled by tailored multipolar flatband resonances from a nonlinear metasurface

Yu Mao, Runhai Hu, Yuanjiang Xiang, Zhixiang Tang

Published Jun 22, 2026• 0 citations
Publisher

Abstract

Nonlinear metasurfaces have emerged as a versatile platform for photon-pair generation through spontaneous parametric down-conversion (SPDC). However, the angular dispersion of optical resonances restricts the emission range and momentum-space uniformity of the generated photon pairs, thereby hindering practical applications in quantum sensing and imaging. Here, we propose and numerically investigate an all-dielectric InGaP metasurface that supports angle-robust photon-pair generation enabled by tailored multipolar flatband resonances. By introducing elliptical nanopores into nonlinear nanodisks, we engineer the far-field coupling and polarization response of weakly dispersive flatband modes while preserving strong field confinement. As a result, the tailored structure exhibits a more than one-order-of-magnitude enhancement in second-harmonic generation efficiency compared with the unperforated design. Based on the quantum-classical correspondence between SPDC and sum-frequency generation (SFG), we further reveal a pronounced enhancement of the nonlinear response and demonstrate stable photon-pair generation with rates up to approximately 2×10 5 Hz over an angular range of ±12°. In addition, the generated photon pairs remain robust over a broad momentum range and show tunable polarization properties under different pump wavelengths. These results provide a practical route toward compact and efficient quantum light sources in nonlinear metasurfaces, and highlight the potential of flatband engineering for applications in quantum imaging and integrated quantum photonics.

DOI
10.1364/ol.605823

Related papers

Flatband nonlinear metasurface for broad-angle photon-pair generation

Yuxin Jiang, Jihua Zhang, Jinyong Ma +2 more

Current nonlinear metasurface photon-pair sources face limitations in angular emission range and uniformity due to optical resonance dispersion, potentially hindering their application in quantum imaging, which demands broad-angle emission for a wide field of view and high resolution. Here, we propose a broad-angle photon-pair source using flatband engineering. We demonstrate that tailored partially etched patterns in a lithium niobate metasurface can facilitate a flatband across a wide transverse wavevector range (±0.2 rad/μm) around a 1573 nm wavelength. The flatband metasurface supports enhanced photon-pair generation at a simulated rate of 539 Hz/mW within a cone of 3° apex angle relative to the pump propagation, which is an order of magnitude broader than previously reported metasurfaces. This general approach is also scalable to other wavelengths, opening new possibilities for compact entangled photon-pair sources in quantum imaging.

APL Quantum•Apr 30, 2025•8 citations

Enhanced tunable photon-pair generation from a nonlinear metasurface with a guided-mode cavity

Tongmiao Fan, Jihua Zhang, Andrey A. Sukhorukov

The ability to generate quantum entangled photon pairs through spontaneous parametric down conversion (SPDC) is playing a pivotal role in many applications in quantum technologies, including quantum communications, quantum computation, and quantum imaging. Metasurfaces, two-dimensional arrays of nanostructures with subwavelength thickness, have recently shown extraordinary capability in manipulating classical and quantum states of light and realizing miniaturized SPDC sources. Whereas previous studies have primarily focused on periodic metasurfaces, we uncover the potential of spatially modulated nanopatterns for further SPDC enhancement and state engineering. Specifically, we propose a nonlinear metasurface featuring a lateral guided-mode cavity formed by two distributed Bragg reflectors. With the quasi-normal mode theory, we predict an SPDC rate up to 157 Hz/mW, which represents about 30 times rate enhancement when compared to the metasurface without a cavity. Furthermore, the cavity supports a continuous set of high-Q resonances across a broad bandwidth, allowing the all-optical tuning of the photon-pair emission directions transverse to the cavity by controlling the pump wavelength, which can find applications in quantum imaging.

arXiv:2505.15026•Physical Review A•May 19, 2025•3 citations

Broad-angle photon-pair generation from flatband quasi-BIC resonant 3R-MoS$_{2}$ metasurfaces

Tingting Liu, Huifu Qiu, Xintong Shi +2 more

Spontaneous parametric down-conversion (SPDC) in ultrathin optical resonant metasurfaces offers a promising platform for integrated quantum light sources. However, conventional resonances suffer from steep momentum dispersion, limiting photon-pair generation to narrow excitation and emission angles. Here, we demonstrate a flatband-resonant 3R-MoS$_{2}$ metasurface for high-efficiency, broad-angle SPDC photon-pair generation. By implementing a supercell symmetry-breaking strategy via Brillouin zone folding, we achieve a flatband quasi-bound states in the continuum (quasi-BICs) resonance in the near-infrared regime that maintains a robust quality factor across a wide range of incident angle. Exploiting the strong local electric field enhancement of resonance and the large second-order susceptibility of 3R-MoS$_{2}$, the metasurface boosts the degenerate SPDC pair-generation rate with orders of magnitude enhancement over an unpatterned film of identical thickness. Crucially, the near-zero band dispersion extends the effective emission angle to $\pm 5^{\circ}$ with negligible spectral drift $\sim 0.1$ nm and high directional tolerance. Under pulsed excitation with a finite spectral bandwidth, the photon pair yield remains high, demonstrating strong spectral locking to the quasi-BIC resonance against pump detunings. This work establishes a versatile strategy for momentum-independent quantum light sources, opening new avenues for scan-free quantum ghost imaging and spatial-frequency quantum processing.

arXiv:2609.07082•Sep 7, 2026•0 citations

Enhanced generation of angle correlated photon-pairs in nonlinear metasurfaces

Andrea Mazzanti, Matthew Parry, Alexander N. Poddubny +3 more

Abstract We reveal that strongly enhanced generation of photon pairs with narrow frequency spectra and sharp angular correlations can be realised through spontaneous parametric down-conversion in metasurfaces. This is facilitated by creating meta-gratings through nano-structuring of nonlinear films of sub-wavelength thickness to support the extended bound state in the continuum resonances, associated with ultra-high Q-factors, at the biphoton wavelengths across a wide range of emission angles. Such spectral features of photons can be beneficial for various applications, including quantum imaging. Our modelling demonstrates a pronounced enhancement, compared to unpatterned films, of the total photon-pair generation rate normalized to the pump power reaching 1.75 kHz mW−1, which is robust with respect to the angular bandwidth of the pump, supporting the feasibility of future experimental realisations.

New Journal of Physics•Mar 1, 2022•25 citations

Generation and shaping of quantum photon-pair states in nonlinear metasurfaces

Andrey A. Sukhorukov

We present theoretical and experimental advances on photon-pair generation through spontaneous parametric down-conversion (SPDC) in nonlinear nanostructures and metasurfaces, underpinning quantum entanglement engineering at sub-wavelength scale for photon shaping with tailored polarization and spatial correlations. We derive explicit theoretical expressions for the measurable photon counts and quantum correlations, incorporating material dispersion and absorption characteristics [Phys. Rev. Lett. 117, 123901 (2016)], and demonstrate experimentally the generation of quantum heralded photon pairs from a single AlGaAs nanodisk [Optica 6, 1416 (2019)]. We further reveal the opportunities to enhance the generation rate through high-Q resonances including bound states in the continuum [doi:10.1117/12.2539888 (2019)]. We also outline the applications of metasurfaces for the manipulation and measurement of multi-photon quantum states for free-space quantum imaging and communications.

Active Photonic Platforms (APP)•Aug 20, 2020•0 citations

Efficient photon-pair generation empowered by dual quasibound states in the continuum

Tingting Liu, Meibao Qin, Siqi Feng +4 more

Here we demonstrate the efficient photon-pair generation via spontaneous parametric down conversion from a semiconductor metasurface supporting dual quasibound states in the continuum (quasi-BICs). In a simple metasurface composed of AlGaAs elliptical nanocyclinders, the two high-$Q$ quasi-BIC resonances that coincide with the generated signal and idler frequencies significantly boost the local electric field. This leads to a substantial enhancement in the reverse classical nonlinear process of sum-frequency generation and subsequently the remarkably high generation rate of photon pairs under the quantum-classical correspondence principle. Within a narrowband wavelength regime around the quasi-BIC resonances, the rate of pair production is enhanced up to $\ensuremath{\sim}{10}^{4}$ Hz, two orders of magnitude larger than that in the Mie resonant AlGaAs nanoantennas. Moreover, the photon pair emission is mainly concentrated in the normal direction with respect to the metasurface, and shows a tunable rate with the $Q$ factor by engineering the rotation angle of nanocylinders. The presented work enables nanoscale sources of high-quality entangled photons which will find applications in advanced quantum imaging and communications.

arXiv:2401.14140•Physical review. B./Physical review. B•Apr 17, 2024•42 citations
Nonlinear metasurfaces have emerged as a versatile platform for photon-pair generation through spontaneous parametric down-conversion (SPDC). However, the angular dispersion of optical resonances restricts the emission range and momentum-space uniformity of the generated photon pairs, thereby hindering practical applications in quantum sensing and imaging. Here, we propose and numerically investigate an all-dielectric InGaP metasurface that supports angle-robust photon-pair generation enabled by tailored multipolar flatband resonances. By introducing elliptical nanopores into nonlinear nanodisks, we engineer the far-field coupling and polarization response of weakly dispersive flatband modes while preserving strong field confinement. As a result, the tailored structure exhibits a more than one-order-of-magnitude enhancement in second-harmonic generation efficiency compared with the unperforated design. Based on the quantum-classical correspondence between SPDC and sum-frequency generation (SFG), we further reveal a pronounced enhancement of the nonlinear response and demonstrate stable photon-pair generation with rates up to approximately 2×10 5 Hz over an angular range of ±12°. In addition, the generated photon pairs remain robust over a broad momentum range and show tunable polarization properties under different pump wavelengths. These results provide a practical route toward compact and efficient quantum light sources in nonlinear metasurfaces, and highlight the potential of flatband engineering for applications in quantum imaging and integrated quantum photonics.
Current nonlinear metasurface photon-pair sources face limitations in angular emission range and uniformity due to optical resonance dispersion, potentially hindering their application in quantum imaging, which demands broad-angle emission for a wide field of view and high resolution. Here, we propose a broad-angle photon-pair source using flatband engineering. We demonstrate that tailored partially etched patterns in a lithium niobate metasurface can facilitate a flatband across a wide transverse wavevector range (±0.2 rad/μm) around a 1573 nm wavelength. The flatband metasurface supports enhanced photon-pair generation at a simulated rate of 539 Hz/mW within a cone of 3° apex angle relative to the pump propagation, which is an order of magnitude broader than previously reported metasurfaces. This general approach is also scalable to other wavelengths, opening new possibilities for compact entangled photon-pair sources in quantum imaging.
The ability to generate quantum entangled photon pairs through spontaneous parametric down conversion (SPDC) is playing a pivotal role in many applications in quantum technologies, including quantum communications, quantum computation, and quantum imaging. Metasurfaces, two-dimensional arrays of nanostructures with subwavelength thickness, have recently shown extraordinary capability in manipulating classical and quantum states of light and realizing miniaturized SPDC sources. Whereas previous studies have primarily focused on periodic metasurfaces, we uncover the potential of spatially modulated nanopatterns for further SPDC enhancement and state engineering. Specifically, we propose a nonlinear metasurface featuring a lateral guided-mode cavity formed by two distributed Bragg reflectors. With the quasi-normal mode theory, we predict an SPDC rate up to 157 Hz/mW, which represents about 30 times rate enhancement when compared to the metasurface without a cavity. Furthermore, the cavity supports a continuous set of high-Q resonances across a broad bandwidth, allowing the all-optical tuning of the photon-pair emission directions transverse to the cavity by controlling the pump wavelength, which can find applications in quantum imaging.
Broad-angle photon-pair generation from flatband quasi-BIC resonant 3R-MoS2_{2}2​ metasurfaces
Spontaneous parametric down-conversion (SPDC) in ultrathin optical resonant metasurfaces offers a promising platform for integrated quantum light sources. However, conventional resonances suffer from steep momentum dispersion, limiting photon-pair generation to narrow excitation and emission angles. Here, we demonstrate a flatband-resonant 3R-MoS2_{2}2​ metasurface for high-efficiency, broad-angle SPDC photon-pair generation. By implementing a supercell symmetry-breaking strategy via Brillouin zone folding, we achieve a flatband quasi-bound states in the continuum (quasi-BICs) resonance in the near-infrared regime that maintains a robust quality factor across a wide range of incident angle. Exploiting the strong local electric field enhancement of resonance and the large second-order susceptibility of 3R-MoS2_{2}2​, the metasurface boosts the degenerate SPDC pair-generation rate with orders of magnitude enhancement over an unpatterned film of identical thickness. Crucially, the near-zero band dispersion extends the effective emission angle to ±5∘\pm 5^{\circ}±5∘ with negligible spectral drift ∼0.1\sim 0.1∼0.1 nm and high directional tolerance. Under pulsed excitation with a finite spectral bandwidth, the photon pair yield remains high, demonstrating strong spectral locking to the quasi-BIC resonance against pump detunings. This work establishes a versatile strategy for momentum-independent quantum light sources, opening new avenues for scan-free quantum ghost imaging and spatial-frequency quantum processing.
Abstract We reveal that strongly enhanced generation of photon pairs with narrow frequency spectra and sharp angular correlations can be realised through spontaneous parametric down-conversion in metasurfaces. This is facilitated by creating meta-gratings through nano-structuring of nonlinear films of sub-wavelength thickness to support the extended bound state in the continuum resonances, associated with ultra-high Q-factors, at the biphoton wavelengths across a wide range of emission angles. Such spectral features of photons can be beneficial for various applications, including quantum imaging. Our modelling demonstrates a pronounced enhancement, compared to unpatterned films, of the total photon-pair generation rate normalized to the pump power reaching 1.75 kHz mW−1, which is robust with respect to the angular bandwidth of the pump, supporting the feasibility of future experimental realisations.
We present theoretical and experimental advances on photon-pair generation through spontaneous parametric down-conversion (SPDC) in nonlinear nanostructures and metasurfaces, underpinning quantum entanglement engineering at sub-wavelength scale for photon shaping with tailored polarization and spatial correlations. We derive explicit theoretical expressions for the measurable photon counts and quantum correlations, incorporating material dispersion and absorption characteristics [Phys. Rev. Lett. 117, 123901 (2016)], and demonstrate experimentally the generation of quantum heralded photon pairs from a single AlGaAs nanodisk [Optica 6, 1416 (2019)]. We further reveal the opportunities to enhance the generation rate through high-Q resonances including bound states in the continuum [doi:10.1117/12.2539888 (2019)]. We also outline the applications of metasurfaces for the manipulation and measurement of multi-photon quantum states for free-space quantum imaging and communications.
Here we demonstrate the efficient photon-pair generation via spontaneous parametric down conversion from a semiconductor metasurface supporting dual quasibound states in the continuum (quasi-BICs). In a simple metasurface composed of AlGaAs elliptical nanocyclinders, the two high-QQQ quasi-BIC resonances that coincide with the generated signal and idler frequencies significantly boost the local electric field. This leads to a substantial enhancement in the reverse classical nonlinear process of sum-frequency generation and subsequently the remarkably high generation rate of photon pairs under the quantum-classical correspondence principle. Within a narrowband wavelength regime around the quasi-BIC resonances, the rate of pair production is enhanced up to $\ensuremath{\sim}{10}^{4}$ Hz, two orders of magnitude larger than that in the Mie resonant AlGaAs nanoantennas. Moreover, the photon pair emission is mainly concentrated in the normal direction with respect to the metasurface, and shows a tunable rate with the QQQ factor by engineering the rotation angle of nanocylinders. The presented work enables nanoscale sources of high-quality entangled photons which will find applications in advanced quantum imaging and communications.