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:2508.05983 · Nanophotonics

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

Tingting Chen, Feihong Xue, Ryan Hogan, Xiaofei Ma, Jiaxuan Zhou, Yule Zhao, Yanling Xiao, Zhilin Ye, Chong Sheng, Qiang Wang, Shining N. Zhu, Hui Liu

Published Aug 4, 2025• 3 citations
arXivHTMLPDF

Abstract

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.

DOI
10.1515/nanoph-2025-0211

Related papers

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

Photon-pair generation using inverse-designed thin-film lithium niobate mode converters

Kiwon Kwon, Hyungjun Heo, Dongjin Lee +10 more

Spontaneous parametric down-conversion (SPDC) has become a key method for generating entangled photon pairs. Periodically poled thin-film lithium niobate (TFLN) waveguides induce strong SPDC but require complex fabrication processes. In this work, we experimentally demonstrate efficient SPDC and second harmonic generation using modal phase matching methods. This is achieved with inverse-designed optical mode converters and low-loss optical waveguides in a single nanofabrication process. Inverse design methods provide enhanced functionalities and compact footprints for the converter. Despite the extensive achievements in inverse-designed photonic integrated circuits, the potential of inverse-designed TFLN quantum photonic devices has been seldom explored. The device shows an on-chip conversion efficiency of 3.95% W−1 cm−2 in second harmonic generation measurements and a coincidence count rate up to 21.2 kHz in SPDC experiments. This work highlights the potential of the inverse-designed TFLN photonic devices and paves the way for their applications in on-chip nonlinear or quantum optics.

APL Photonics•May 1, 2024•20 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

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

High-performance photon-pair source using a two-photon polymerized strip-loaded lithium niobate waveguide

Muhamed A. Sewidan, Alexandra Rittmeier, Laura Bollmers +11 more

Integrated photon-pair sources, providing scalability solutions, are crucial for large-scale realizations of quantum photonic technologies. Their traditional fabrication techniques, such as etching, are often complex, require long development cycles, and are resource inefficient in case of fabrication imperfections or failures. The two-photon polymerization (2PP) technique can offer a rapid, efficient, and reproducible alternative for the fabrication of integrated photonic devices. Here, we demonstrate an integrated photon-pair source based on a 2PP-defined strip-loaded waveguide on a periodically poled thin-film lithium niobate (TFLN) platform. The device generates photon pairs through type-II spontaneous parametric down-conversion (SPDC), employing first-order quasi-phase matching (QPM) with TM-polarized excitation light. The device achieves an on-chip pair generation rate of 4.357 MHz and a coincidence-to-accidental ratio (CAR) of ∼404. To prove the flexibility and versatility of the fabrication technique, the waveguides were erased from the LN substrate and reprinted, reaching comparable performance. This work demonstrates the potential of 2PP as a rapid production technique for high-performance integrated photon-pair sources, offering a practical solution to the limitations of traditional fabrication techniques and showcasing both reproducibility of the fabrication and the reusability of the substrate.

Integrated Optics: Devices, Materials, and Technologies•Jan 24, 2025•0 citations

Spontaneous parametric downconversion photon pair generation in small footprint X-cut periodically poled lithium niobate micro-resonator

Hyeon Hwang, Woojin Noh, Mohamad Reza Nurrahman +5 more

Spontaneous parametric downconversion (SPDC) has been crucial for producing non-classical light, such as correlated photon pairs and squeezed states, essential for optical quantum technologies. Recently, thin-film lithium niobate (TFLN)-based devices have enabled high-performance SPDC in on-chip integrated photonic platforms. Here, we developed an X-cut periodically poled lithium niobate (PPLN) racetrack micro-resonator with a compact footprint and demonstrated bright SPDC photon pair generation characterized by distinct resonances and high extraction efficiency. We separately assessed the internal and loaded photon pair generation rates, measuring them at 4.525 MHz/µW and 62.73 kHz/µW, respectively. Our platform is integrated with maturing electro-/thermo-optic TFLN circuit elements and has meaningful potential for advancing active quantum photonic applications.

Optics Letters•Aug 29, 2024•14 citations
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.
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.
Spontaneous parametric down-conversion (SPDC) has become a key method for generating entangled photon pairs. Periodically poled thin-film lithium niobate (TFLN) waveguides induce strong SPDC but require complex fabrication processes. In this work, we experimentally demonstrate efficient SPDC and second harmonic generation using modal phase matching methods. This is achieved with inverse-designed optical mode converters and low-loss optical waveguides in a single nanofabrication process. Inverse design methods provide enhanced functionalities and compact footprints for the converter. Despite the extensive achievements in inverse-designed photonic integrated circuits, the potential of inverse-designed TFLN quantum photonic devices has been seldom explored. The device shows an on-chip conversion efficiency of 3.95% W−1 cm−2 in second harmonic generation measurements and a coincidence count rate up to 21.2 kHz in SPDC experiments. This work highlights the potential of the inverse-designed TFLN photonic devices and paves the way for their applications in on-chip nonlinear or quantum optics.
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.
Integrated photon-pair sources, providing scalability solutions, are crucial for large-scale realizations of quantum photonic technologies. Their traditional fabrication techniques, such as etching, are often complex, require long development cycles, and are resource inefficient in case of fabrication imperfections or failures. The two-photon polymerization (2PP) technique can offer a rapid, efficient, and reproducible alternative for the fabrication of integrated photonic devices. Here, we demonstrate an integrated photon-pair source based on a 2PP-defined strip-loaded waveguide on a periodically poled thin-film lithium niobate (TFLN) platform. The device generates photon pairs through type-II spontaneous parametric down-conversion (SPDC), employing first-order quasi-phase matching (QPM) with TM-polarized excitation light. The device achieves an on-chip pair generation rate of 4.357 MHz and a coincidence-to-accidental ratio (CAR) of ∼404. To prove the flexibility and versatility of the fabrication technique, the waveguides were erased from the LN substrate and reprinted, reaching comparable performance. This work demonstrates the potential of 2PP as a rapid production technique for high-performance integrated photon-pair sources, offering a practical solution to the limitations of traditional fabrication techniques and showcasing both reproducibility of the fabrication and the reusability of the substrate.
Spontaneous parametric downconversion (SPDC) has been crucial for producing non-classical light, such as correlated photon pairs and squeezed states, essential for optical quantum technologies. Recently, thin-film lithium niobate (TFLN)-based devices have enabled high-performance SPDC in on-chip integrated photonic platforms. Here, we developed an X-cut periodically poled lithium niobate (PPLN) racetrack micro-resonator with a compact footprint and demonstrated bright SPDC photon pair generation characterized by distinct resonances and high extraction efficiency. We separately assessed the internal and loaded photon pair generation rates, measuring them at 4.525 MHz/µW and 62.73 kHz/µW, respectively. Our platform is integrated with maturing electro-/thermo-optic TFLN circuit elements and has meaningful potential for advancing active quantum photonic applications.