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

arXiv:2412.11372 · Laser & Photonics Review

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

Xiao‐Xu Fang, Haoyang Du, Xiuquan Zhang, Lei Wang, Feng Chen, He Lu

Published Aug 23, 2024• 17 citations
arXivHTMLPDF

Abstract

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.

DOI
10.1002/lpor.202400782

Related papers

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

Modal phase-matching in thin-film lithium niobate waveguides for efficient generation of entangled photon pairs

Jiacheng Liu, Jia-Chen Duan, Pingyu Zhu +6 more

Thin-film lithium niobate (TFLN) waveguides have emerged as a pivotal platform for on-chip spontaneous parametric down-conversion (SPDC), serving as a crucible for the generation of entangled photon pairs. The periodic poling of TFLN, while capable of generating high-efficiency SPDC, demands intricate fabrication processes that can be onerous in terms of scalability and manufacturability. In this work, we introduce a novel approach to the generation of entangled photon pairs via SPDC within TFLN waveguides, harnessing the principles of modal phase-matching (MPM). To address the challenge of efficiently exciting pump light typically in a higher-order mode, we have engineered a mode converter that couples two asymmetrically dimensioned waveguides. This converter adeptly transforms the fundamental mode into a higher-order mode, demonstrating a conversion loss of 1.55 dB at 785 nm with a 3 dB bandwidth exceeding 30 nm. Subsequently, we have showcased the device's capabilities by characterizing the pair generation rate (PGR), coincidences-to-accidentals ratio (CAR), and spectral profile of the entangled photon source. Our findings present a simplified and versatile method for the on-chip generation of entangled photon sources, which may pave the way for the application in the realms of quantum information processing and communication technologies.

Optics Express•Oct 13, 2024•11 citations

Efficient high‐quality photon pair generation in modal phase‐matched thin‐film lithium niobate micro‐ring resonators

Tingting Chen, Feihong Xue, Ryan Hogan +9 more

Efficient generation of high-quality photon pairs is essential for modern quantum technologies. Micro-ring resonator is an ideal platform for studying on-chip photon sources due to strong nonlinear effect, resonant-enhanced optical fields, and high integration. Thin-film lithium niobate (TFLN) micro-ring resonators with periodically poled quasi-phase matching have shown high-quality photon pair generation. However, periodic poling technology remains expensive and requires complex fabrication hindering its scalability and capability for practical application in nonlinear photonic devices. To address this, we propose a scalable approach using TFLN micro-ring resonators based on modal phase matching to achieve cost-effective, efficient high-quality photon pair generation, significantly simplifying fabrication. We achieved pair generation rates up to 40.2 MHz/mW through spontaneous parametric down-conversion, with coincidence-to-accidental ratios exceeding 1,200. By combining micro-ring resonance enhancement with modal phase matching, our approach reduces device size and fabrication cost while maintaining high nonlinear efficiency. These results advance the development of compact, efficient on-chip photon sources for next-generation nonlinear and quantum photonic applications.

arXiv:2508.05983•Nanophotonics•Aug 4, 2025•3 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

Wavelength-tunable and high-heralding-efficiency quantum photon source in a birefringent phase-matched lithium niobate waveguide

Qi-Tao Zhu, Xiao‐Xu Fang, He Lu

Lithium niobate (LN) is a birefringent material, where the strong birefringence thermo-optic effect is promising for the generation of a quantum photon source with a widely tunable wavelength. Here, we demonstrate birefringent phase matching in a 20-mm-long waveguide fabricated on a 5- μ m-thick x -cut lithium niobate on insulator (LNOI). The waveguide is deviated from the optical axis of LN by an angle of 53.5 ∘ , enabling the phase matching between telecom and visible wavelengths. The phase-matching wavelength of this device can be thermally tuned with rate of 0.6 nm/K. We demonstrate the type-1 spontaneous parametric downconversion to generate photon pairs with a brightness of 4.7 MHz/mW and a coincidence-to-accidental ratio of up to 2.8 × 10 5 . Furthermore, the heralded single photon is obtained from the photon pair with an efficiency of 13.8% and a count rate of up to 37.8 kHz.

Optics Letters•Feb 12, 2025•1 citation

Cascaded second-order processes for high-purity photon pair generation in layer-poled thin-film lithium niobate

Marco Clementi, Olivia Hefti, Enrico Melani +12 more

Frequency-degenerate photon pairs are a key resource for quantum information processing. Yet, their generation via nonlinear parametric processes is often accompanied by parasitic interactions that hinder state purity. We present a novel approach based on dual-pump, cascaded sum-frequency generation (SFG) and spontaneous parametric down-conversion (SPDC) within a single layer-poled thin-film lithium niobate waveguide. By exploiting modal phase matching, our scheme effectively suppresses spurious photons originating from single-pump processes. This compact, single-pass architecture operates entirely in the telecom band and eliminates the need for complex filtering or microresonator structures. Experimentally, we demonstrate degenerate photon-pair generation with a brightness of (1.0 ± 0.3) × 105 Hz nm−1 mW−2 and more than 40 dB suppression of parasitic photon-pair emission. Our results establish a scalable, low-noise platform for high-purity quantum light sources and open a pathway toward on-chip squeezed light generation via cascaded processes.

Quantum Computing, Communication, and Simulation•Mar 5, 2026•0 citations
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.
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.
Thin-film lithium niobate (TFLN) waveguides have emerged as a pivotal platform for on-chip spontaneous parametric down-conversion (SPDC), serving as a crucible for the generation of entangled photon pairs. The periodic poling of TFLN, while capable of generating high-efficiency SPDC, demands intricate fabrication processes that can be onerous in terms of scalability and manufacturability. In this work, we introduce a novel approach to the generation of entangled photon pairs via SPDC within TFLN waveguides, harnessing the principles of modal phase-matching (MPM). To address the challenge of efficiently exciting pump light typically in a higher-order mode, we have engineered a mode converter that couples two asymmetrically dimensioned waveguides. This converter adeptly transforms the fundamental mode into a higher-order mode, demonstrating a conversion loss of 1.55 dB at 785 nm with a 3 dB bandwidth exceeding 30 nm. Subsequently, we have showcased the device's capabilities by characterizing the pair generation rate (PGR), coincidences-to-accidentals ratio (CAR), and spectral profile of the entangled photon source. Our findings present a simplified and versatile method for the on-chip generation of entangled photon sources, which may pave the way for the application in the realms of quantum information processing and communication technologies.
Efficient generation of high-quality photon pairs is essential for modern quantum technologies. Micro-ring resonator is an ideal platform for studying on-chip photon sources due to strong nonlinear effect, resonant-enhanced optical fields, and high integration. Thin-film lithium niobate (TFLN) micro-ring resonators with periodically poled quasi-phase matching have shown high-quality photon pair generation. However, periodic poling technology remains expensive and requires complex fabrication hindering its scalability and capability for practical application in nonlinear photonic devices. To address this, we propose a scalable approach using TFLN micro-ring resonators based on modal phase matching to achieve cost-effective, efficient high-quality photon pair generation, significantly simplifying fabrication. We achieved pair generation rates up to 40.2 MHz/mW through spontaneous parametric down-conversion, with coincidence-to-accidental ratios exceeding 1,200. By combining micro-ring resonance enhancement with modal phase matching, our approach reduces device size and fabrication cost while maintaining high nonlinear efficiency. These results advance the development of compact, efficient on-chip photon sources for next-generation nonlinear and quantum photonic applications.
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.
Lithium niobate (LN) is a birefringent material, where the strong birefringence thermo-optic effect is promising for the generation of a quantum photon source with a widely tunable wavelength. Here, we demonstrate birefringent phase matching in a 20-mm-long waveguide fabricated on a 5- μ m-thick x -cut lithium niobate on insulator (LNOI). The waveguide is deviated from the optical axis of LN by an angle of 53.5 ∘ , enabling the phase matching between telecom and visible wavelengths. The phase-matching wavelength of this device can be thermally tuned with rate of 0.6 nm/K. We demonstrate the type-1 spontaneous parametric downconversion to generate photon pairs with a brightness of 4.7 MHz/mW and a coincidence-to-accidental ratio of up to 2.8 × 10 5 . Furthermore, the heralded single photon is obtained from the photon pair with an efficiency of 13.8% and a count rate of up to 37.8 kHz.
Frequency-degenerate photon pairs are a key resource for quantum information processing. Yet, their generation via nonlinear parametric processes is often accompanied by parasitic interactions that hinder state purity. We present a novel approach based on dual-pump, cascaded sum-frequency generation (SFG) and spontaneous parametric down-conversion (SPDC) within a single layer-poled thin-film lithium niobate waveguide. By exploiting modal phase matching, our scheme effectively suppresses spurious photons originating from single-pump processes. This compact, single-pass architecture operates entirely in the telecom band and eliminates the need for complex filtering or microresonator structures. Experimentally, we demonstrate degenerate photon-pair generation with a brightness of (1.0 ± 0.3) × 105 Hz nm−1 mW−2 and more than 40 dB suppression of parasitic photon-pair emission. Our results establish a scalable, low-noise platform for high-purity quantum light sources and open a pathway toward on-chip squeezed light generation via cascaded processes.