Pub Date : 2025-11-18DOI: 10.1515/nanoph-2025-0469
Pietro Tassan, Etsuki Kobiyama, Jan David Fischbach, Dario Ballarini, Luca Moretti, Lorenzo Dominici, Milena De Giorgi, Daniele Sanvitto, Michael Forster, Ullrich Scherf, Antonis Olziersky, Carsten Rockstuhl, Thomas Jebb Sturges, Rainer F. Mahrt, Darius Urbonas, Thilo Stöferle
A central challenge for advancing polariton-based circuits is the controlled and scalable coupling of individual condensates. Existing approaches based on etched or epitaxially grown microcavities are fabrication-intensive and restrict in-plane coupling. To overcome these limitations, we introduce a lithographically defined silicon-based platform of high-contrast grating (HCG) microcavities with a ladder-type π-conjugated polymer. In this system, doublet cavities exhibit mode hybridization into bonding and antibonding states, where coupling is mediated across shared HCG mirrors. Extending the design to arrays, N -coupled condensates exhibit systematic red-shifts of the condensate energy, due to delocalization, and a progressive threshold reduction, consistent with extended binding modes. Our experimental results are quantitatively supported by transition-matrix multi-scattering simulations, together with tight-binding modelling. First-order coherence measurements using Michelson interferometry confirm the existence of spatially extended condensates with exponentially decaying temporal coherence. Altogether, these results establish a scalable route toward integrated polariton devices and quantum photonic networks.
{"title":"Integrated array of coupled exciton–polariton condensates","authors":"Pietro Tassan, Etsuki Kobiyama, Jan David Fischbach, Dario Ballarini, Luca Moretti, Lorenzo Dominici, Milena De Giorgi, Daniele Sanvitto, Michael Forster, Ullrich Scherf, Antonis Olziersky, Carsten Rockstuhl, Thomas Jebb Sturges, Rainer F. Mahrt, Darius Urbonas, Thilo Stöferle","doi":"10.1515/nanoph-2025-0469","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0469","url":null,"abstract":"A central challenge for advancing polariton-based circuits is the controlled and scalable coupling of individual condensates. Existing approaches based on etched or epitaxially grown microcavities are fabrication-intensive and restrict in-plane coupling. To overcome these limitations, we introduce a lithographically defined silicon-based platform of high-contrast grating (HCG) microcavities with a ladder-type π-conjugated polymer. In this system, doublet cavities exhibit mode hybridization into bonding and antibonding states, where coupling is mediated across shared HCG mirrors. Extending the design to arrays, <jats:italic>N</jats:italic> -coupled condensates exhibit systematic red-shifts of the condensate energy, due to delocalization, and a progressive threshold reduction, consistent with extended binding modes. Our experimental results are quantitatively supported by transition-matrix multi-scattering simulations, together with tight-binding modelling. First-order coherence measurements using Michelson interferometry confirm the existence of spatially extended condensates with exponentially decaying temporal coherence. Altogether, these results establish a scalable route toward integrated polariton devices and quantum photonic networks.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"6 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-18DOI: 10.1515/nanoph-2025-0388
Elif Nur Dayi, Omer Can Karaman, Diotime Pellet, Alan R. Bowman, Giulia Tagliabue
Second-harmonic generation (SHG) is a powerful surface-specific probe for centrosymmetric materials, with broad relevance to energy and biological interfaces. Plasmonic nanomaterials have been extensively utilized to amplify this nonlinear response. Yet, material instability has constrained most studies to gold, despite the significance of plasmonic metals such as copper for catalysis. Here, we demonstrate stable and anisotropic SHG from monocrystalline copper, overcoming long-standing challenges associated with surface degradation. By leveraging an on-substrate synthesis approach that yields atomically flat and oxidation-resistant Cu microflakes, we enable reliable SHG measurements and reveal a strong cross-polarized response with C 3 v surface symmetry. The SHG signal remains stable over 3 h of continuous femtosecond excitation, highlighting the remarkable optical robustness of the Cu microflakes. These results reinforce the viability of monocrystalline Cu as a robust platform for nonlinear nanophotonics and surface-sensitive spectroscopy, expanding the range of copper-based optical applications.
{"title":"Cross-polarized and stable second harmonic generation from monocrystalline copper","authors":"Elif Nur Dayi, Omer Can Karaman, Diotime Pellet, Alan R. Bowman, Giulia Tagliabue","doi":"10.1515/nanoph-2025-0388","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0388","url":null,"abstract":"Second-harmonic generation (SHG) is a powerful surface-specific probe for centrosymmetric materials, with broad relevance to energy and biological interfaces. Plasmonic nanomaterials have been extensively utilized to amplify this nonlinear response. Yet, material instability has constrained most studies to gold, despite the significance of plasmonic metals such as copper for catalysis. Here, we demonstrate stable and anisotropic SHG from monocrystalline copper, overcoming long-standing challenges associated with surface degradation. By leveraging an on-substrate synthesis approach that yields atomically flat and oxidation-resistant Cu microflakes, we enable reliable SHG measurements and reveal a strong cross-polarized response with <jats:italic>C</jats:italic> <jats:sub> 3 <jats:italic>v</jats:italic> </jats:sub> surface symmetry. The SHG signal remains stable over 3 h of continuous femtosecond excitation, highlighting the remarkable optical robustness of the Cu microflakes. These results reinforce the viability of monocrystalline Cu as a robust platform for nonlinear nanophotonics and surface-sensitive spectroscopy, expanding the range of copper-based optical applications.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"131 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-18DOI: 10.1515/nanoph-2025-0476
Zijun Huang, Rui Ma, Qiang Ying, Peng Hao, Wei Ke, Xinlun Cai, X. Steve Yao
Integrated optoelectronic oscillators (OEOs) have emerged as pivotal enablers of compact, energy-efficient solutions for generating high-frequency radio-frequency (RF) signals with exceptional spectral purity – an essential demand in the advancement of radar and communication technologies. Yet, the quest for ultra-low phase noise near the carrier remains hampered by laser frequency instability and environmental fluctuations. In this work, we unveil the first photonic-integrated, high-order subharmonic injection-locked OEO realized on a thin-film lithium niobate (TFLN) platform, seamlessly uniting a Mach–Zehnder modulator (MZM) and an add-drop microring resonator (MRR) in a monolithic architecture. By harnessing an external RF source operating at a fractional subharmonic (1/2 N , with N = 1, 3, 5…) of the OEO’s free-running frequency, our system achieves robust locking to the 2 N -th harmonic of the injected signal, made possible through the beating of ± N -th order modulation sidebands – precisely selected by the dual resonances of the MRR – at the photodetector. We experimentally demonstrate the generation of 28.7 GHz signals via second- and sixth-order subharmonic injection locking, employing external RF injections at 14.35 GHz and 4.78 GHz, respectively. This yields an outstanding side-mode suppression ratio (SMSR) exceeding 78 dB and remarkably low spurious emissions. Furthermore, the measured phase noise achieves values below −80 dBc/Hz at 100 Hz and below −115 dBc/Hz at 10 kHz offsets from the 28.7 GHz carrier, delineating a new standard for integrated OEO performance.
集成光电振荡器（OEOs）已经成为紧凑，节能的解决方案的关键推动者，用于产生具有特殊频谱纯度的高频射频（RF）信号-这是雷达和通信技术进步的基本需求。然而，对载波附近超低相位噪声的追求仍然受到激光频率不稳定性和环境波动的阻碍。在这项工作中，我们推出了第一个在薄膜铌酸锂（TFLN）平台上实现的光子集成、高阶次谐波注入锁定OEO，将马赫-曾德尔调制器（MZM）和加滴微环谐振器（MRR）无缝地结合在一个单片架构中。通过利用在OEO自由运行频率的分数次谐波（1/2 N, N = 1,3,5…）下工作的外部射频源，我们的系统实现了对注入信号的2 N次谐波的鲁棒锁定，这是通过在光电探测器上敲打±N阶调制边带（由MRR的双共振精确选择）来实现的。通过实验证明，采用14.35 GHz和4.78 GHz的外部射频注入，通过二阶和六阶亚谐波注入锁定产生28.7 GHz信号。这产生了出色的侧模抑制比（SMSR）超过78 dB和非常低的杂散发射。此外，测得的相位噪声在100hz时低于- 80 dBc/Hz，在28.7 GHz载波的10 kHz偏移时低于- 115 dBc/Hz，描绘了集成OEO性能的新标准。
{"title":"Subharmonic injection-locked photonic integrated thin-film lithium niobate optoelectronic oscillator","authors":"Zijun Huang, Rui Ma, Qiang Ying, Peng Hao, Wei Ke, Xinlun Cai, X. Steve Yao","doi":"10.1515/nanoph-2025-0476","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0476","url":null,"abstract":"Integrated optoelectronic oscillators (OEOs) have emerged as pivotal enablers of compact, energy-efficient solutions for generating high-frequency radio-frequency (RF) signals with exceptional spectral purity – an essential demand in the advancement of radar and communication technologies. Yet, the quest for ultra-low phase noise near the carrier remains hampered by laser frequency instability and environmental fluctuations. In this work, we unveil the first photonic-integrated, high-order subharmonic injection-locked OEO realized on a thin-film lithium niobate (TFLN) platform, seamlessly uniting a Mach–Zehnder modulator (MZM) and an add-drop microring resonator (MRR) in a monolithic architecture. By harnessing an external RF source operating at a fractional subharmonic (1/2 <jats:italic>N</jats:italic> , with <jats:italic>N</jats:italic> = 1, 3, 5…) of the OEO’s free-running frequency, our system achieves robust locking to the 2 <jats:italic>N</jats:italic> -th harmonic of the injected signal, made possible through the beating of ± <jats:italic>N</jats:italic> -th order modulation sidebands – precisely selected by the dual resonances of the MRR – at the photodetector. We experimentally demonstrate the generation of 28.7 GHz signals via second- and sixth-order subharmonic injection locking, employing external RF injections at 14.35 GHz and 4.78 GHz, respectively. This yields an outstanding side-mode suppression ratio (SMSR) exceeding 78 dB and remarkably low spurious emissions. Furthermore, the measured phase noise achieves values below −80 dBc/Hz at 100 Hz and below −115 dBc/Hz at 10 kHz offsets from the 28.7 GHz carrier, delineating a new standard for integrated OEO performance.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"122 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thin-film lithium niobate (TFLN) has emerged as a powerful platform for integrated nonlinear optics owing to its large χ(2) nonlinearity, tight confinement and flexible tunability. To fully excavate such superior nonlinear optical properties, domain engineering is commonly adopted to fulfill the phase matching condition of χ(2) processes. During the past decade, various domain engineered TFLN nonlinear optical devices have been demonstrated, showing extremely high length-normalized nonlinear optical conversion efficiencies. However, application-driven scenarios demand absolute energy conversion in nonlinear frequency conversion rather than length-normalized efficiencies, but the progress has been limited by imperfect fabrication processes. In this work, we realize effective on-chip nonlinear energy conversion by developing low-loss and high-quality domain engineered TFLN waveguides with long interaction length. Ion beam trimming (IBT) technique and an etching-prior-poling workflow are adopted for such fabrication. Optical characterization yields an overall second-harmonic generation (SHG) efficiency of 2,590 %/W. A high pump depletion of 85.7 % is demonstrated under continuous-wave operation, which directly reflects strong nonlinear energy conversion. These results may lead to breakthroughs in applications like classical optical frequency conversion, quantum frequency conversion, and quantum light generation.
{"title":"High pump depletion second-harmonic generation using domain engineered thin-film lithium niobate waveguides","authors":"Chenyu Wang, Mengwen Chen, Xiao-Hui Tian, Zishuo Gu, Jie Tang, Yong Zhang, Zikang Wang, Kunpeng Jia, Chenyang Shi, Xiaowen Gu, Guang Qian, Zhenlin Wang, Shi-Ning Zhu, Zhenda Xie","doi":"10.1515/nanoph-2025-0505","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0505","url":null,"abstract":"Thin-film lithium niobate (TFLN) has emerged as a powerful platform for integrated nonlinear optics owing to its large <jats:italic>χ</jats:italic> <jats:sup>(2)</jats:sup> nonlinearity, tight confinement and flexible tunability. To fully excavate such superior nonlinear optical properties, domain engineering is commonly adopted to fulfill the phase matching condition of <jats:italic>χ</jats:italic> <jats:sup>(2)</jats:sup> processes. During the past decade, various domain engineered TFLN nonlinear optical devices have been demonstrated, showing extremely high length-normalized nonlinear optical conversion efficiencies. However, application-driven scenarios demand absolute energy conversion in nonlinear frequency conversion rather than length-normalized efficiencies, but the progress has been limited by imperfect fabrication processes. In this work, we realize effective on-chip nonlinear energy conversion by developing low-loss and high-quality domain engineered TFLN waveguides with long interaction length. Ion beam trimming (IBT) technique and an etching-prior-poling workflow are adopted for such fabrication. Optical characterization yields an overall second-harmonic generation (SHG) efficiency of 2,590 %/W. A high pump depletion of 85.7 % is demonstrated under continuous-wave operation, which directly reflects strong nonlinear energy conversion. These results may lead to breakthroughs in applications like classical optical frequency conversion, quantum frequency conversion, and quantum light generation.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"7 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To address the critical limitations of conventional band-switching technologies – such as their slow speed, high energy consumption, and mechanical instability – this research introduces a novel deep-learning-driven framework for the intelligent inverse design of polarization-multiplexed metasurfaces. This approach represents a paradigm shift from traditional methods by enabling single-step, computational discovery of metasurface designs that directly encode two distinct optical functions within a single flat device. At the heart of our framework is a custom-designed deep neural network that seamlessly integrates parallel convolutional layers for robust feature extraction with cascaded regression modules for high-precision prediction. This hybrid architecture allows us to engineer sub-wavelength meta-atoms to achieve desired optical responses rigorously. As a groundbreaking demonstration, we designed and optimized a metasurface that achieves dynamic band switching solely through polarization modulation: it generates a targeted transmission peak in the O-band (1,260–1,360 nm) under y -polarization and an independent peak in the C-band (1,530–1,565 nm) under x -polarization. This mechanism eliminates the need for moving parts. The resulting device exhibits a switching efficiency orders of magnitude greater than its mechanical counterparts, while simultaneously offering enhanced stability, lower power consumption, and inherent adaptability for reconfigurable optical networks. Our work not only validates a specific device but also establishes a robust and generalizable design paradigm, underscoring the transformative potential of uniting deep learning with metasurfaces to achieve ultra-fast, intelligent, and efficient photonic systems for next-generation optical communications.
{"title":"Deep-learning-based polarization-dependent switching metasurface in dual-band for optical communication","authors":"Yihan Yan, Yunkai Wu, Yangwen Wang, Jiahao Li, Jingtian Hu, Xu Wang","doi":"10.1515/nanoph-2025-0370","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0370","url":null,"abstract":"To address the critical limitations of conventional band-switching technologies – such as their slow speed, high energy consumption, and mechanical instability – this research introduces a novel deep-learning-driven framework for the intelligent inverse design of polarization-multiplexed metasurfaces. This approach represents a paradigm shift from traditional methods by enabling single-step, computational discovery of metasurface designs that directly encode two distinct optical functions within a single flat device. At the heart of our framework is a custom-designed deep neural network that seamlessly integrates parallel convolutional layers for robust feature extraction with cascaded regression modules for high-precision prediction. This hybrid architecture allows us to engineer sub-wavelength meta-atoms to achieve desired optical responses rigorously. As a groundbreaking demonstration, we designed and optimized a metasurface that achieves dynamic band switching solely through polarization modulation: it generates a targeted transmission peak in the O-band (1,260–1,360 nm) under <jats:italic>y</jats:italic> -polarization and an independent peak in the C-band (1,530–1,565 nm) under <jats:italic>x</jats:italic> -polarization. This mechanism eliminates the need for moving parts. The resulting device exhibits a switching efficiency orders of magnitude greater than its mechanical counterparts, while simultaneously offering enhanced stability, lower power consumption, and inherent adaptability for reconfigurable optical networks. Our work not only validates a specific device but also establishes a robust and generalizable design paradigm, underscoring the transformative potential of uniting deep learning with metasurfaces to achieve ultra-fast, intelligent, and efficient photonic systems for next-generation optical communications.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"26 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report the first demonstration of surface relief formation by irradiating material with non-degenerate hybrid vortex modes. These modes are formed via the coherent superposition of two Laguerre–Gaussian (LG) modes with different orbital angular momentum (OAM) indices, and they carry non-zero OAM. Intriguingly, the spatially localized vortex fields, which are associated with multiple phase singularities of the non-degenerate hybrid vortex modes and spin angular momentum (SAM) of circular polarization, can be visualized as fist-like protrusions produced within the fabricated surface relief structures. This demonstration offers new insights into fundamental light–matter interactions via SAM-OAM coupling effects and opens the door to a deeper understanding of the mechanisms underlying the formation of vortex lattices and vortex–antivortex pairs in condensed matter physics. This demonstration also provides a method for fabricating chiral surface relief structures with an odd number of spiral arms, which may be utilized in advanced optical data storage and chiral metasurface applications.
{"title":"Surface relief formation with light possessing multiple vortices","authors":"Junjie Zhao, Kazuro Kizaki, Atsushi Taguchi, Madoka Ono, Soki Hirayama, Takashige Omatsu","doi":"10.1515/nanoph-2025-0387","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0387","url":null,"abstract":"We report the first demonstration of surface relief formation by irradiating material with non-degenerate hybrid vortex modes. These modes are formed via the coherent superposition of two Laguerre–Gaussian (LG) modes with different orbital angular momentum (OAM) indices, and they carry non-zero OAM. Intriguingly, the spatially localized vortex fields, which are associated with multiple phase singularities of the non-degenerate hybrid vortex modes and spin angular momentum (SAM) of circular polarization, can be visualized as fist-like protrusions produced within the fabricated surface relief structures. This demonstration offers new insights into fundamental light–matter interactions via SAM-OAM coupling effects and opens the door to a deeper understanding of the mechanisms underlying the formation of vortex lattices and vortex–antivortex pairs in condensed matter physics. This demonstration also provides a method for fabricating chiral surface relief structures with an odd number of spiral arms, which may be utilized in advanced optical data storage and chiral metasurface applications.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"64 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-17DOI: 10.1515/nanoph-2025-0442
Sae R. Endo, Dasom Kim, Shuang Liang, Geon Lee, Sunghwan Kim, Alan Covarrubias-Morales, Minah Seo, Michael J. Manfra, Dukhyung Lee, Motoaki Bamba, Junichiro Kono
The multimode ultrastrong coupling (USC) regime has emerged as a novel platform for accessing previously inaccessible phenomena in cavity quantum electrodynamics. Of particular interest are cavity-mediated correlations between local and nonlocal excitations, or equivalently, between modes at zero and finite in-plane momentum, which offer new opportunities for controlling light–matter interactions across space. However, direct experimental evidence of such interactions has remained elusive. Here, we demonstrate nonlocal multimode coupling in a Landau polariton system, where cavity photons simultaneously interact with the zero-momentum cyclotron resonance and finite-momentum magnetoplasmons of GaAs two-dimensional electron gas. Our slot cavities, with their subwavelength mode volumes, supply in-plane momentum components that enable the excitation of finite-momentum matter modes. Terahertz time-domain magnetospectroscopy measurements reveal a clear splitting of the upper-polariton branch, arising from hybridization between magnetoplasmon modes and the cavity–cyclotron-resonance hybrids. Extracted coupling strengths confirm USC of the cyclotron resonance and strong coupling of the magnetoplasmon modes to the cavity field, respectively. The experimental results are well captured by the multimode Hopfield model and finite-element simulations. These findings establish a pathway for engineering multimode light–matter interactions involving zero- and finite-momentum matter modes in the USC regime.
{"title":"Cavity-mediated coupling between local and nonlocal modes in Landau polaritons","authors":"Sae R. Endo, Dasom Kim, Shuang Liang, Geon Lee, Sunghwan Kim, Alan Covarrubias-Morales, Minah Seo, Michael J. Manfra, Dukhyung Lee, Motoaki Bamba, Junichiro Kono","doi":"10.1515/nanoph-2025-0442","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0442","url":null,"abstract":"The multimode ultrastrong coupling (USC) regime has emerged as a novel platform for accessing previously inaccessible phenomena in cavity quantum electrodynamics. Of particular interest are cavity-mediated correlations between local and nonlocal excitations, or equivalently, between modes at zero and finite in-plane momentum, which offer new opportunities for controlling light–matter interactions across space. However, direct experimental evidence of such interactions has remained elusive. Here, we demonstrate nonlocal multimode coupling in a Landau polariton system, where cavity photons simultaneously interact with the zero-momentum cyclotron resonance and finite-momentum magnetoplasmons of GaAs two-dimensional electron gas. Our slot cavities, with their subwavelength mode volumes, supply in-plane momentum components that enable the excitation of finite-momentum matter modes. Terahertz time-domain magnetospectroscopy measurements reveal a clear splitting of the upper-polariton branch, arising from hybridization between magnetoplasmon modes and the cavity–cyclotron-resonance hybrids. Extracted coupling strengths confirm USC of the cyclotron resonance and strong coupling of the magnetoplasmon modes to the cavity field, respectively. The experimental results are well captured by the multimode Hopfield model and finite-element simulations. These findings establish a pathway for engineering multimode light–matter interactions involving zero- and finite-momentum matter modes in the USC regime.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"143 2 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Erbium-doped thin-film lithium niobate (Er 3+ :TFLN) enables integrated photonic devices through its efficient photoluminescence. However, the fixed transition energies of erbium ions intrinsically restrict emission to the telecommunications C-band (1530–1565 nm), limiting spectral versatility. To transcend this constraint, we engineered periodically poled Er 3+ :TFLN waveguides that concurrently integrate optical amplification and nonlinear frequency conversion. Within this platform, we harnessed erbium ions stimulated emission under 980 nm pumping to achieve net optical gain (0.8 dB) at 1538.2 nm. Simultaneously, we exploited the quasi-phase-matching (QPM) capability of the poled structure to perform sum-frequency generation (SFG) between the 976.0 nm pump and the amplified 1538.2 nm signal. This dual-process yielded visible emission at 597.1 nm with 84 nW output power and a normalized conversion efficiency of 68 % W −1 cm −2 . Critically, this work demonstrates-for the first time in Er 3+ :TFLN-spectral extension beyond the C-band through synergistic pump amplification and nonlinear mixing. Our monolithic architecture establishes a new paradigm for broadband on-chip photonics, enabling applications including multi-wavelength laser sources, quantum entangled photon pair generators, and on-chip biophotonic sensing systems.
{"title":"Light-amplification-assisted sum-frequency generation in erbium-doped thin-film lithium niobate optical waveguides","authors":"Yan Liu, Zhenzhong Hao, Xiao Wu, Shuting Kang, Rui Ma, Yuchen Zhang, Hongde Liu, Dahuai Zheng, Yongfa Kong, Fang Bo, Guoquan Zhang, Jingjun Xu","doi":"10.1515/nanoph-2025-0359","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0359","url":null,"abstract":"Erbium-doped thin-film lithium niobate (Er <jats:sup>3+</jats:sup> :TFLN) enables integrated photonic devices through its efficient photoluminescence. However, the fixed transition energies of erbium ions intrinsically restrict emission to the telecommunications C-band (1530–1565 nm), limiting spectral versatility. To transcend this constraint, we engineered periodically poled Er <jats:sup>3+</jats:sup> :TFLN waveguides that concurrently integrate optical amplification and nonlinear frequency conversion. Within this platform, we harnessed erbium ions stimulated emission under 980 nm pumping to achieve net optical gain (0.8 dB) at 1538.2 nm. Simultaneously, we exploited the quasi-phase-matching (QPM) capability of the poled structure to perform sum-frequency generation (SFG) between the 976.0 nm pump and the amplified 1538.2 nm signal. This dual-process yielded visible emission at 597.1 nm with 84 nW output power and a normalized conversion efficiency of 68 % W <jats:sup>−1</jats:sup> cm <jats:sup>−2</jats:sup> . Critically, this work demonstrates-for the first time in Er <jats:sup>3+</jats:sup> :TFLN-spectral extension beyond the C-band through synergistic pump amplification and nonlinear mixing. Our monolithic architecture establishes a new paradigm for broadband on-chip photonics, enabling applications including multi-wavelength laser sources, quantum entangled photon pair generators, and on-chip biophotonic sensing systems.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"171 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145498617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1515/nanoph-2025-0471
Liying Chen, Alexander M. McKillop, Ashley P. Fidler, Marissa L. Weichman
Polaritons – hybrid light-matter states formed from the strong coupling of a bright molecular transition with a confined photonic mode – may offer new opportunities for optical control of molecular behavior. Vibrational strong coupling (VSC) has been reported to impact ground-state chemical reactivity, but its influence on electronic excited-state dynamics remains unexplored. Here, we take a first step towards excited-state VSC by demonstrating optical modulation of the ReCl(CO) 3 (bpy), (bpy = 2,2-bipyridine) complex under VSC using femtosecond ultraviolet (UV)-pump/infrared (IR)-probe spectroscopy. We establish ground-state VSC of ReCl(CO) 3 (bpy) in a microfluidic Fabry-Pérot cavity equipped with indium tin oxide (ITO)-coated mirrors. ITO is effectively dichroic as it is reflective in the IR and transmissive in the UV-visible and therefore minimizes optical interference. Excitation with UV pump light drives ReCl(CO) 3 (bpy) into a manifold of electronic excited states that subsequently undergo non-radiative relaxation dynamics. We probe the transient response of the strongly-coupled system in the mid-IR, observing both Rabi contraction and cavity-filtered excited-state absorption signatures. We reconstruct the intrinsic response of intracavity molecules from the transient cavity transmission spectra to enable quantitative comparison with extracavity control experiments. We report no changes in the excited-state dynamics of ReCl(CO) 3 (bpy) under ground-state VSC. However, we do observe significant amplification of transient vibrational signals due to classical cavity-enhanced optical effects. This effort lays the groundwork to pursue direct excited-state VSC aimed at modulating photochemical reactivity.
{"title":"Ultrafast optical modulation of vibrational strong coupling in ReCl(CO) 3 (2,2-bipyridine)","authors":"Liying Chen, Alexander M. McKillop, Ashley P. Fidler, Marissa L. Weichman","doi":"10.1515/nanoph-2025-0471","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0471","url":null,"abstract":"Polaritons – hybrid light-matter states formed from the strong coupling of a bright molecular transition with a confined photonic mode – may offer new opportunities for optical control of molecular behavior. Vibrational strong coupling (VSC) has been reported to impact ground-state chemical reactivity, but its influence on electronic excited-state dynamics remains unexplored. Here, we take a first step towards excited-state VSC by demonstrating optical modulation of the ReCl(CO) <jats:sub>3</jats:sub> (bpy), (bpy = 2,2-bipyridine) complex under VSC using femtosecond ultraviolet (UV)-pump/infrared (IR)-probe spectroscopy. We establish ground-state VSC of ReCl(CO) <jats:sub>3</jats:sub> (bpy) in a microfluidic Fabry-Pérot cavity equipped with indium tin oxide (ITO)-coated mirrors. ITO is effectively dichroic as it is reflective in the IR and transmissive in the UV-visible and therefore minimizes optical interference. Excitation with UV pump light drives ReCl(CO) <jats:sub>3</jats:sub> (bpy) into a manifold of electronic excited states that subsequently undergo non-radiative relaxation dynamics. We probe the transient response of the strongly-coupled system in the mid-IR, observing both Rabi contraction and cavity-filtered excited-state absorption signatures. We reconstruct the intrinsic response of intracavity molecules from the transient cavity transmission spectra to enable quantitative comparison with extracavity control experiments. We report no changes in the excited-state dynamics of ReCl(CO) <jats:sub>3</jats:sub> (bpy) under ground-state VSC. However, we do observe significant amplification of transient vibrational signals due to classical cavity-enhanced optical effects. This effort lays the groundwork to pursue direct excited-state VSC aimed at modulating photochemical reactivity.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"137 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145491793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1515/nanoph-2025-0298
Byoung-Uk Sohn, George F. R. Chen, Hongwei Gao, Doris K. T. Ng, Dawn T. H. Tan
Photonic topological insulators provide robust transport of light, enabling interesting phenomena such as unidirectional light propagation and immunity to disorder. The discovery of how to effectively break time reversal symmetry was an important development in the field of photonic topological insulators. Knowledge on how to implement designs in all-dielectric systems was an especially crucial development, enabling complementary metal-oxide semiconductor-based materials and processes to be used to study such structures, accelerating their pace of innovation. On the other hand, transmission of high-speed data is of fundamental importance in communications systems prolific in data centers and telecommunications. In this paper, we demonstrate robust transport of high-speed non-return-to-zero (NRZ) and pulse amplitude modulation 4 (PAM4) in a photonic topological insulator based on the quantum valley Hall effect. The structure utilizes a Kagome lattice with a slightly broken symmetry to achieve a domain wall between two regions with half-integer valley Chern numbers. The topological structure’s immunity to backscattering allows high-speed data to be transmission through a zigzag path with four 120° bends. Characterization of reference devices including a trivial device and photonic waveguide device shows that the topological device is superior in the robust transport of high-speed data, enabling a low BER of 10 −8 for 30 Gbps NRZ data and an open eye observed for 100 Gbps PAM4 data even when transmitted through a zigzag optical path.
{"title":"Robust transport of high-speed data in a topological valley Hall insulator","authors":"Byoung-Uk Sohn, George F. R. Chen, Hongwei Gao, Doris K. T. Ng, Dawn T. H. Tan","doi":"10.1515/nanoph-2025-0298","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0298","url":null,"abstract":"Photonic topological insulators provide robust transport of light, enabling interesting phenomena such as unidirectional light propagation and immunity to disorder. The discovery of how to effectively break time reversal symmetry was an important development in the field of photonic topological insulators. Knowledge on how to implement designs in all-dielectric systems was an especially crucial development, enabling complementary metal-oxide semiconductor-based materials and processes to be used to study such structures, accelerating their pace of innovation. On the other hand, transmission of high-speed data is of fundamental importance in communications systems prolific in data centers and telecommunications. In this paper, we demonstrate robust transport of high-speed non-return-to-zero (NRZ) and pulse amplitude modulation 4 (PAM4) in a photonic topological insulator based on the quantum valley Hall effect. The structure utilizes a Kagome lattice with a slightly broken symmetry to achieve a domain wall between two regions with half-integer valley Chern numbers. The topological structure’s immunity to backscattering allows high-speed data to be transmission through a zigzag path with four 120° bends. Characterization of reference devices including a trivial device and photonic waveguide device shows that the topological device is superior in the robust transport of high-speed data, enabling a low BER of 10 <jats:sup>−8</jats:sup> for 30 Gbps NRZ data and an open eye observed for 100 Gbps PAM4 data even when transmitted through a zigzag optical path.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"29 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145491790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：