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

Laser & Photonics Review

A Scalable Quadratic Nonlinear Silicon Photonics Platform With Printable Entangled Photon‐Pair Sources

Tom Vandekerckhove, Jasper De Witte, Lisa De Jaeger, Ewoud Vissers, Sofie Janssen, Peter Verheyen, Neha Chiruvolu Singh, Dieter Bode, Martin Davi, Filippo Ferraro, Philippe P. Absil, Sadhishkumar Balakrishnan, Joris Van Campenhout, Dries Van Thourhout, Günther Roelkens, Stéphane Clemmen, Bart Kuyken

Published Sep 25, 2025• 4 citations
Publisher

Abstract

Abstract The integration of second‐order optical nonlinearities into scalable photonic platforms remains a key challenge due to their large sensitivity to fabrication variations. Here, a scalable quadratic nonlinear platform is presented that harnesses the maturity and scalability of existing CMOS processes by heterogeneously integrating periodically poled lithium niobate (PPLN) onto a silicon photonics platform. A generic PPLN design enables frequency conversion on two distinct waveguide geometries with efficiencies comparable to reported lithium niobate on insulator (LNOI) rib waveguides. Reproducible phase‐matching is achieved across the full radius of a commercial 200 mm silicon photonics wafer, leveraging superior CMOS fabrication tolerances. Furthermore, a tuning mechanism is introduced for both blue‐ and red‐shifting of the operating wavelength, fully compensating fabrication‐induced offsets. This enables deterministic phase‐matching over an entire wafer and yields a strategy for wafer‐scale phase‐matched quadratic nonlinearities. Finally, printable photon‐pair sources are realized via spontaneous parametric down‐conversion (SPDC), highlighting the platform's potential for large‐scale quantum optical circuits. These results pave the way for wafer‐scale integration of second‐order optical nonlinearities in large photonic systems.

DOI
10.1002/lpor.202501357

Related papers

A scalable quadratic nonlinear silicon photonics platform with printable entangled photon-pair sources

Tom Vandekerckhove, De Witte, Jasper, Lisa De Jaeger +14 more

The integration of second-order optical nonlinearities into scalable photonic platforms remains a key challenge due to their large sensitivity to fabrication variations. Here, we present a scalable quadratic nonlinear platform that harnesses the maturity and scalability of existing CMOS processes by heterogeneously integrating periodically poled lithium niobate (PPLN) onto a silicon photonics platform. A generic PPLN design enables frequency conversion on two distinct waveguide geometries with efficiencies comparable to LNOI rib waveguides. We achieve reproducible phase-matching across the full radius of a commercial 200 mm silicon photonics wafer, leveraging superior CMOS fabrication tolerances. Furthermore, we introduce a tuning mechanism for both blue- and red-shifting of the operating wavelength, fully compensating fabrication-induced offsets. This enables deterministic phase-matching over an entire wafer and yields a strategy for wafer-scale phase-matched quadratic nonlinearities. Finally, we realize printable photon-pair sources via spontaneous parametric down-conversion, highlighting the platform's potential for large-scale quantum optical circuits. These results pave the way for wafer-scale integration of second-order optical nonlinearities in large photonic systems.

arXiv:2503.08783•Mar 11, 2025•1 citation

Efficient photon-pair generation in layer-poled lithium niobate nanophotonic waveguides

Xiaodong Shi, Sakthi Sanjeev Mohanraj, Veerendra Dhyani +7 more

Abstract Integrated photon-pair sources are crucial for scalable photonic quantum systems. Thin-film lithium niobate is a promising platform for on-chip photon-pair generation through spontaneous parametric down-conversion (SPDC). However, the device implementation faces practical challenges. Periodically poled lithium niobate (PPLN), despite enabling flexible quasi-phase matching, suffers from poor fabrication reliability and device repeatability, while conventional modal phase matching (MPM) methods yield limited efficiencies due to inadequate mode overlaps. Here, we introduce a layer-poled lithium niobate (LPLN) nanophotonic waveguide for efficient photon-pair generation. It leverages layer-wise polarity inversion through electrical poling to break spatial symmetry and significantly enhance nonlinear interactions for MPM, achieving a notable normalized second-harmonic generation (SHG) conversion efficiency of 4615% W-1 cm-2. Through a cascaded SHG and SPDC process, we demonstrate photon-pair generation with a normalized brightness of 3.1×106 Hz nm-1 mW-2 in a 3.3 mm long LPLN waveguide, surpassing existing on-chip sources under similar operating configurations. Crucially, our LPLN waveguides offer enhanced fabrication reliability and reduced sensitivity to geometric variations and temperature fluctuations compared to PPLN devices. We expect LPLN to become a promising solution for on-chip nonlinear wavelength conversion and non-classical light generation, with immediate applications in quantum communication, networking, and on-chip photonic quantum information processing.

arXiv:2405.10943•Light Science & Applications•Oct 3, 2024•69 citations

Poling-free Spontaneous Parametric Down Conversion without for Silicon Carbide and Lithium Niobate photonics

Tim F. Weiss, Hamed Arianfard, Yang Yang +1 more

State-of-the-art photon sources based on spontaneous parametric down-conversion (SPDC) currently rely on artificial structuring of the material nonlinearity to satisfy phase-matching conditions. This technique, known as periodic poling, is available only in a limited number of material platforms and introduces additional fabrication steps and errors, which are detrimental to up-scaling efforts. Here, we present a device architecture that enables SPDC of a wide range of frequencies without the need for periodic poling. We present explicit designs and calculations for 4H Silicon Carbide on-insulator, in which SPDC photon generation is so far unavailable, and thin-film Lithium Niobate on-insulator, a state-of-the-art quantum photonics platform. Our design, based on mode conversion and subsequent modal phase-matched SPDC, facilitates a CMOS compatible $χ^{(2)}$ platform, and simplifies photon sources by removing the requirement of periodic poling and the associated additional fabrication complexity.

physics.opticsCross-listedarXiv:2604.17723•Scientific Reports•Apr 21, 2026•3 citations

High‐Efficiency On‐Chip Quantum Photon Source in Modal Phase‐Matched Lithium Niobate Nanowaveguide

Xiao‐Xu Fang, Haoyang Du, Xiuquan Zhang +3 more

Abstract Thin‐film lithium niobate on insulator (LNOI) emerges as a promising platform for integrated quantum photon source, enabling scalable on‐chip quantum information processing. The most popular technique to overcome the phase mismatching between interacting waves in waveguide is periodic poling, which is intrinsically sensitive to poling uniformity. Here, an alternative strategy to offset the phase mismatching of spontaneous parametric down‐conversion (SPDC) process, so‐called modal phase matching, in a straight waveguide fabricated on a dual‐layer LNOI is reported. The dual‐layer LNOI consists of two 300 nm lithium niobates with opposite directions, which significantly enhances the spatial overlap between fundamental and high‐order modes and thus enables efficient SPDC. This dual‐layer waveguide generates photon pairs with pair generation rate of 41.77 GHz , which exhibits excellent signal‐to‐noise performance with coincidence‐to‐accidental ratio up to 58298 1297. Moreover, a heralded single‐photon source with second‐order autocorrelation and heralded rate exceeding 100 kHz is observed. The results provide an experiment‐friendly approach for efficient generation of quantum photon sources and benefit the on‐chip quantum information processing based on LNOI.

arXiv:2412.11372•Laser & Photonics Review•Aug 23, 2024•17 citations

Broadband quantum photon source in a step-chirped periodically poled lithium niobate waveguide

Xiao‐Xu Fang, Guoliang Shentu, he lu

Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate (CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). The SHG achieves an average efficiency of 91%/W/cm 2 over the first-harmonic wavelength range of 1510 nm–1620 nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775 nm, 780 nm, and 785 nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99 THz (846 nm) and 21 MHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.

Optics Express•Jan 13, 2026•2 citations

Efficient generation of broadband photon pairs in shallow-etched lithium niobate nanowaveguides

Xiao‐Xu Fang, Leiran Wang, He Lu

We design and fabricate shallow-etched periodically poled lithium niobate waveguides to realize highly efficient broadband spontaneous parametric down-conversion (SPDC) on nanophotonic chips. The shallow-etched waveguide can tolerate the non-uniformities of waveguide width induced by fabrication imperfections, enabling the generation of photon pairs with high count rate and bandwidth. We demonstrate photon-pair generation with a high brightness of 11.7 GHz/mW and bandwidth of 22 THz in a 5.7-mm-long PPLN waveguide. The generated photon pairs exhibit a strong temporal correlation with a coincidence-to-accidental ratio of up to 16262±850. Our results confirm the feasibility of shallow etching in the fabrication of an efficient SPDC device on the platform of lithium niobate on an insulator, and benefit quantum information processing with a broadband photon source.

arXiv:2406.17439•Optics Express•May 30, 2024•19 citations
Abstract The integration of second‐order optical nonlinearities into scalable photonic platforms remains a key challenge due to their large sensitivity to fabrication variations. Here, a scalable quadratic nonlinear platform is presented that harnesses the maturity and scalability of existing CMOS processes by heterogeneously integrating periodically poled lithium niobate (PPLN) onto a silicon photonics platform. A generic PPLN design enables frequency conversion on two distinct waveguide geometries with efficiencies comparable to reported lithium niobate on insulator (LNOI) rib waveguides. Reproducible phase‐matching is achieved across the full radius of a commercial 200 mm silicon photonics wafer, leveraging superior CMOS fabrication tolerances. Furthermore, a tuning mechanism is introduced for both blue‐ and red‐shifting of the operating wavelength, fully compensating fabrication‐induced offsets. This enables deterministic phase‐matching over an entire wafer and yields a strategy for wafer‐scale phase‐matched quadratic nonlinearities. Finally, printable photon‐pair sources are realized via spontaneous parametric down‐conversion (SPDC), highlighting the platform's potential for large‐scale quantum optical circuits. These results pave the way for wafer‐scale integration of second‐order optical nonlinearities in large photonic systems.
The integration of second-order optical nonlinearities into scalable photonic platforms remains a key challenge due to their large sensitivity to fabrication variations. Here, we present a scalable quadratic nonlinear platform that harnesses the maturity and scalability of existing CMOS processes by heterogeneously integrating periodically poled lithium niobate (PPLN) onto a silicon photonics platform. A generic PPLN design enables frequency conversion on two distinct waveguide geometries with efficiencies comparable to LNOI rib waveguides. We achieve reproducible phase-matching across the full radius of a commercial 200 mm silicon photonics wafer, leveraging superior CMOS fabrication tolerances. Furthermore, we introduce a tuning mechanism for both blue- and red-shifting of the operating wavelength, fully compensating fabrication-induced offsets. This enables deterministic phase-matching over an entire wafer and yields a strategy for wafer-scale phase-matched quadratic nonlinearities. Finally, we realize printable photon-pair sources via spontaneous parametric down-conversion, highlighting the platform's potential for large-scale quantum optical circuits. These results pave the way for wafer-scale integration of second-order optical nonlinearities in large photonic systems.
Abstract Integrated photon-pair sources are crucial for scalable photonic quantum systems. Thin-film lithium niobate is a promising platform for on-chip photon-pair generation through spontaneous parametric down-conversion (SPDC). However, the device implementation faces practical challenges. Periodically poled lithium niobate (PPLN), despite enabling flexible quasi-phase matching, suffers from poor fabrication reliability and device repeatability, while conventional modal phase matching (MPM) methods yield limited efficiencies due to inadequate mode overlaps. Here, we introduce a layer-poled lithium niobate (LPLN) nanophotonic waveguide for efficient photon-pair generation. It leverages layer-wise polarity inversion through electrical poling to break spatial symmetry and significantly enhance nonlinear interactions for MPM, achieving a notable normalized second-harmonic generation (SHG) conversion efficiency of 4615% W-1 cm-2. Through a cascaded SHG and SPDC process, we demonstrate photon-pair generation with a normalized brightness of 3.1×106 Hz nm-1 mW-2 in a 3.3 mm long LPLN waveguide, surpassing existing on-chip sources under similar operating configurations. Crucially, our LPLN waveguides offer enhanced fabrication reliability and reduced sensitivity to geometric variations and temperature fluctuations compared to PPLN devices. We expect LPLN to become a promising solution for on-chip nonlinear wavelength conversion and non-classical light generation, with immediate applications in quantum communication, networking, and on-chip photonic quantum information processing.
State-of-the-art photon sources based on spontaneous parametric down-conversion (SPDC) currently rely on artificial structuring of the material nonlinearity to satisfy phase-matching conditions. This technique, known as periodic poling, is available only in a limited number of material platforms and introduces additional fabrication steps and errors, which are detrimental to up-scaling efforts. Here, we present a device architecture that enables SPDC of a wide range of frequencies without the need for periodic poling. We present explicit designs and calculations for 4H Silicon Carbide on-insulator, in which SPDC photon generation is so far unavailable, and thin-film Lithium Niobate on-insulator, a state-of-the-art quantum photonics platform. Our design, based on mode conversion and subsequent modal phase-matched SPDC, facilitates a CMOS compatible χ(2)χ^{(2)}χ(2) platform, and simplifies photon sources by removing the requirement of periodic poling and the associated additional fabrication complexity.
Abstract Thin‐film lithium niobate on insulator (LNOI) emerges as a promising platform for integrated quantum photon source, enabling scalable on‐chip quantum information processing. The most popular technique to overcome the phase mismatching between interacting waves in waveguide is periodic poling, which is intrinsically sensitive to poling uniformity. Here, an alternative strategy to offset the phase mismatching of spontaneous parametric down‐conversion (SPDC) process, so‐called modal phase matching, in a straight waveguide fabricated on a dual‐layer LNOI is reported. The dual‐layer LNOI consists of two 300 nm lithium niobates with opposite directions, which significantly enhances the spatial overlap between fundamental and high‐order modes and thus enables efficient SPDC. This dual‐layer waveguide generates photon pairs with pair generation rate of 41.77 GHz , which exhibits excellent signal‐to‐noise performance with coincidence‐to‐accidental ratio up to 58298 1297. Moreover, a heralded single‐photon source with second‐order autocorrelation and heralded rate exceeding 100 kHz is observed. The results provide an experiment‐friendly approach for efficient generation of quantum photon sources and benefit the on‐chip quantum information processing based on LNOI.
Broadband nonlinear optical devices play a critical role in both classical and quantum optics. Here, we design and fabricate a 6.82-mm-long step-chirped periodically poled lithium niobate (CPPLN) waveguide on lithium niobate on insulator, which enables quasi-phase matching over a broad bandwidth for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC). The SHG achieves an average efficiency of 91%/W/cm 2 over the first-harmonic wavelength range of 1510 nm–1620 nm, paving the way for realizing SPDC across a wide range of pump wavelengths. For SPDC, by tuning the pump wavelength to 775 nm, 780 nm, and 785 nm, we achieve broadband photon-pair generation with a maximum full bandwidth and brightness up to 99 THz (846 nm) and 21 MHz/mW/nm, respectively. Our findings provide an efficient and experiment-friendly approach for generating broadband photon pairs, which holds significant promise for advancing applications in quantum metrology.
We design and fabricate shallow-etched periodically poled lithium niobate waveguides to realize highly efficient broadband spontaneous parametric down-conversion (SPDC) on nanophotonic chips. The shallow-etched waveguide can tolerate the non-uniformities of waveguide width induced by fabrication imperfections, enabling the generation of photon pairs with high count rate and bandwidth. We demonstrate photon-pair generation with a high brightness of 11.7 GHz/mW and bandwidth of 22 THz in a 5.7-mm-long PPLN waveguide. The generated photon pairs exhibit a strong temporal correlation with a coincidence-to-accidental ratio of up to 16262±850. Our results confirm the feasibility of shallow etching in the fabrication of an efficient SPDC device on the platform of lithium niobate on an insulator, and benefit quantum information processing with a broadband photon source.