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}
This work presents a novel approach to create and dynamically control quasi-bound states in the continuum (BIC) resonances through the hybridization of 1D and 2D metasurfaces using micro-electromechanical systems (MEMS). The quasi-BIC resonance’s central wavelength and quality factor are precisely tuned by introducing out-of-plane symmetry breaking through a silicon MEMS membrane positioned above a 1D silicon metasurface. The proposed design achieves ultranarrow resonance linewidths with the spectral tuning range exceeding 60 nm while maintaining a constant quality factor. This tuning capability, realized through both horizontal displacement within a 1D metasurface and vertical MEMS membrane movement, offers a new degree of freedom for manipulating quasi-BIC resonances. The proposed hybridization of 2D and 1D metasurfaces using a MEMS mechanism provides a practical route to dynamic modulation of transmission resonance characteristics, making it a promising candidate for tunable filters, spectroscopy, imaging, and sensing applications.
{"title":"Tunable bound states in the continuum through hybridization of 1D and 2D metasurfaces","authors":"Fedor Kovalev, Mariusz Martyniuk, Andrey Miroshnichenko, Ilya Shadrivov","doi":"10.1515/nanoph-2025-0432","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0432","url":null,"abstract":"This work presents a novel approach to create and dynamically control quasi-bound states in the continuum (BIC) resonances through the hybridization of 1D and 2D metasurfaces using micro-electromechanical systems (MEMS). The quasi-BIC resonance’s central wavelength and quality factor are precisely tuned by introducing out-of-plane symmetry breaking through a silicon MEMS membrane positioned above a 1D silicon metasurface. The proposed design achieves ultranarrow resonance linewidths with the spectral tuning range exceeding 60 nm while maintaining a constant quality factor. This tuning capability, realized through both horizontal displacement within a 1D metasurface and vertical MEMS membrane movement, offers a new degree of freedom for manipulating quasi-BIC resonances. The proposed hybridization of 2D and 1D metasurfaces using a MEMS mechanism provides a practical route to dynamic modulation of transmission resonance characteristics, making it a promising candidate for tunable filters, spectroscopy, imaging, and sensing applications.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"80 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145484726","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 : 2025-11-10DOI: 10.1515/nanoph-2025-0398
Qilin Zheng, Li Liang, Shunji Yang, Luyang Tong, Wenqiang Wang, Jibo Tang, Yu Zhang, Bintong Huang, Xiaobo He
Spectroscopy underpins a wide range of applications, including biomedical diagnostics, precision agriculture, remote sensing, and industrial process control. Recent advances in silicon and microwave photonic integration have facilitated the miniaturization of spectroscopic systems, enabling portable, real-time analysis. However, the realization of a chip-scale platform that simultaneously achieves broadband coverage, high resolution, and scalable low-cost fabrication – particularly in the near-infrared (NIR) regime – remains a significant challenge. Here, we present a compact and cost-effective NIR spectroscopic sensing chip that monolithically integrates a plasmonic bandpass filter array with InGaAs photodetectors. The device is fabricated via single-step lithography and features a nanohole array with geometrically tunable narrowband transmission spanning 900–1,700 nm, exhibiting a full width at half maximum (FWHM) of 5.0 nm and a peak Q -factor of ∼284. The plasmonic filters are directly integrated with the detectors through a SiN x spacer layer, eliminating post-fabrication alignment and enhancing scalability. A 16-channel super-pixel layout, combined with computational spectral reconstruction, enables ∼1 nm resolution near 1,550 nm and supports high-fidelity spectral imaging. This work demonstrates a scalable, detector-compatible approach to on-chip NIR spectroscopy, offering a promising route toward deployable, compact spectral sensing platforms.
{"title":"Broadband on-chip spectral sensing via directly integrated narrowband plasmonic filters for computational multispectral imaging","authors":"Qilin Zheng, Li Liang, Shunji Yang, Luyang Tong, Wenqiang Wang, Jibo Tang, Yu Zhang, Bintong Huang, Xiaobo He","doi":"10.1515/nanoph-2025-0398","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0398","url":null,"abstract":"Spectroscopy underpins a wide range of applications, including biomedical diagnostics, precision agriculture, remote sensing, and industrial process control. Recent advances in silicon and microwave photonic integration have facilitated the miniaturization of spectroscopic systems, enabling portable, real-time analysis. However, the realization of a chip-scale platform that simultaneously achieves broadband coverage, high resolution, and scalable low-cost fabrication – particularly in the near-infrared (NIR) regime – remains a significant challenge. Here, we present a compact and cost-effective NIR spectroscopic sensing chip that monolithically integrates a plasmonic bandpass filter array with InGaAs photodetectors. The device is fabricated via single-step lithography and features a nanohole array with geometrically tunable narrowband transmission spanning 900–1,700 nm, exhibiting a full width at half maximum (FWHM) of 5.0 nm and a peak <jats:italic>Q</jats:italic> -factor of ∼284. The plasmonic filters are directly integrated with the detectors through a SiN <jats:sub> <jats:italic>x</jats:italic> </jats:sub> spacer layer, eliminating post-fabrication alignment and enhancing scalability. A 16-channel super-pixel layout, combined with computational spectral reconstruction, enables ∼1 nm resolution near 1,550 nm and supports high-fidelity spectral imaging. This work demonstrates a scalable, detector-compatible approach to on-chip NIR spectroscopy, offering a promising route toward deployable, compact spectral sensing platforms.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"39 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145484831","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 : 2025-11-09DOI: 10.1515/nanoph-2025-0296
Jiawei Zhang, Weipeng Zhang, Tengji Xu, Lei Xu, Eli A. Doris, Bhavin J. Shastri, Chaoran Huang, Paul R. Prucnal
CMOS-compatible photonic integrated circuits (PICs) are emerging as a promising platform in artificial intelligence (AI) computing. Owing to the compact footprint of microring resonators (MRRs) and the enhanced interconnect efficiency enabled by wavelength division multiplexing (WDM), MRR-based photonic neural networks (PNNs) are particularly promising for large-scale integration. However, the scalability and energy efficiency of such systems are fundamentally limited by the MRR resonance wavelength variations induced by fabrication process variations (FPVs) and environmental fluctuations. Existing solutions use post-fabrication approaches or thermo-optic tuning, incurring high control power and additional process complexity. In this work, we introduce an online training and pruning method that addresses this challenge, adapting to FPV-induced and thermally induced shifts in MRR resonance wavelength. By incorporating a power-aware pruning term into the conventional loss function, our approach simultaneously optimizes the PNN accuracy and the total power consumption for MRR tuning. In proof-of-concept on-chip experiments on the Iris dataset, our system PNNs can adaptively train to maintain above 90 % classification accuracy in a wide temperature range of 26–40 °C while achieving a 44.7 % reduction in tuning power via pruning. Additionally, our approach reduces the power consumption by orders-of-magnitude on larger datasets. By addressing chip-to-chip variation and minimizing power requirements, our approach significantly improves the scalability and energy efficiency of MRR-based integrated analog photonic processors, paving the way for large-scale PICs to enable versatile applications including neural networks, photonic switching, LiDAR, and radio-frequency beamforming.
{"title":"Online training and pruning of multi-wavelength photonic neural networks","authors":"Jiawei Zhang, Weipeng Zhang, Tengji Xu, Lei Xu, Eli A. Doris, Bhavin J. Shastri, Chaoran Huang, Paul R. Prucnal","doi":"10.1515/nanoph-2025-0296","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0296","url":null,"abstract":"CMOS-compatible photonic integrated circuits (PICs) are emerging as a promising platform in artificial intelligence (AI) computing. Owing to the compact footprint of microring resonators (MRRs) and the enhanced interconnect efficiency enabled by wavelength division multiplexing (WDM), MRR-based photonic neural networks (PNNs) are particularly promising for large-scale integration. However, the scalability and energy efficiency of such systems are fundamentally limited by the MRR resonance wavelength variations induced by fabrication process variations (FPVs) and environmental fluctuations. Existing solutions use post-fabrication approaches or thermo-optic tuning, incurring high control power and additional process complexity. In this work, we introduce an online training and pruning method that addresses this challenge, adapting to FPV-induced and thermally induced shifts in MRR resonance wavelength. By incorporating a power-aware pruning term into the conventional loss function, our approach simultaneously optimizes the PNN accuracy and the total power consumption for MRR tuning. In proof-of-concept on-chip experiments on the Iris dataset, our system PNNs can adaptively train to maintain above 90 % classification accuracy in a wide temperature range of 26–40 °C while achieving a 44.7 % reduction in tuning power via pruning. Additionally, our approach reduces the power consumption by orders-of-magnitude on larger datasets. By addressing chip-to-chip variation and minimizing power requirements, our approach significantly improves the scalability and energy efficiency of MRR-based integrated analog photonic processors, paving the way for large-scale PICs to enable versatile applications including neural networks, photonic switching, LiDAR, and radio-frequency beamforming.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"133 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145472882","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 : 2025-11-09DOI: 10.1515/nanoph-2025-0391
Amir Ali Marefati, Mahdieh Bozorgi
We present a high performance ultra-broadband optical absorber based on a metal–insulator–metal (MIM) configuration, enhanced by two-dimensional (2D) materials: graphene and borophene. The base design includes a titanium resonator, an SiO 2 dielectric spacer, and a gold ground plane. Performance optimization is achieved through integration of 2D materials, anti-reflection coatings (ARC), and tuning of structural parameters, Fermi energy, and surface carrier density. Numerical simulations using the finite difference time domain (FDTD) method show that incorporating borophene, due to its exceptionally high carrier density, leads to remarkable enhancement in both absorption amplitude and spectral bandwidth. When integrated with an optimized antireflection coating (ARC), the borophene-based absorber achieves over 90 % absorption across 790–3,232 nm (bandwidth: 2,442 nm), corresponding to a 136 % enhancement over the base design. For absorption above 80 %, the bandwidth extends from 760 to 3,306 nm (2,546 nm), yielding a 125 % improvement. The associated fractional bandwidths are 121 % and 125 %, respectively. By comparison, the graphene-based counterpart, with a properly tuned ARC and Fermi level, delivers over 90 % absorption within 923–2,108 nm (1,185 nm, 13 % improvement), while maintaining absorption above 80 % across 911–2,256 nm (1,345 nm, 12 % improvement), with corresponding fractional bandwidths of 78 % and 84 %. Comparative analysis underscores the critical importance of 2D material selection and placement, ARC and resonator optimization, and optical tuning in achieving optimal performance. These results indicate strong potential for practical applications in advanced optoelectronic and photonic devices, including infrared imaging, optical sensing, broadband photodetectors, solar energy harvesting, and stealth or thermal camouflage systems.
{"title":"Record-level, exceptionally broadband borophene-based absorber with near-perfect absorption: design and comparison with a graphene-based counterpart","authors":"Amir Ali Marefati, Mahdieh Bozorgi","doi":"10.1515/nanoph-2025-0391","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0391","url":null,"abstract":"We present a high performance ultra-broadband optical absorber based on a metal–insulator–metal (MIM) configuration, enhanced by two-dimensional (2D) materials: graphene and borophene. The base design includes a titanium resonator, an SiO <jats:sub>2</jats:sub> dielectric spacer, and a gold ground plane. Performance optimization is achieved through integration of 2D materials, anti-reflection coatings (ARC), and tuning of structural parameters, Fermi energy, and surface carrier density. Numerical simulations using the finite difference time domain (FDTD) method show that incorporating borophene, due to its exceptionally high carrier density, leads to remarkable enhancement in both absorption amplitude and spectral bandwidth. When integrated with an optimized antireflection coating (ARC), the borophene-based absorber achieves over 90 % absorption across 790–3,232 nm (bandwidth: 2,442 nm), corresponding to a 136 % enhancement over the base design. For absorption above 80 %, the bandwidth extends from 760 to 3,306 nm (2,546 nm), yielding a 125 % improvement. The associated fractional bandwidths are 121 % and 125 %, respectively. By comparison, the graphene-based counterpart, with a properly tuned ARC and Fermi level, delivers over 90 % absorption within 923–2,108 nm (1,185 nm, 13 % improvement), while maintaining absorption above 80 % across 911–2,256 nm (1,345 nm, 12 % improvement), with corresponding fractional bandwidths of 78 % and 84 %. Comparative analysis underscores the critical importance of 2D material selection and placement, ARC and resonator optimization, and optical tuning in achieving optimal performance. These results indicate strong potential for practical applications in advanced optoelectronic and photonic devices, including infrared imaging, optical sensing, broadband photodetectors, solar energy harvesting, and stealth or thermal camouflage systems.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"80 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145472744","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}
Dynamically tunable metasurfaces based on phase-change materials (PCMs) have become important platforms for realizing reconfigurable optical systems. Nevertheless, achieving multiple independent functionalities within a single device, particularly under polarization multiplexing, remains difficult due to limited design flexibility. In this study, we present a metasurface design framework that reaches the theoretical maximum of six independent phase modulation functions by simultaneously controlling the polarization states and the crystallinity of the PCM. This is implemented through a pixel-extension strategy, where each nanofin functions independently in amorphous state and is reorganized into superpixels with distinct optical responses in crystalline state. To support this, a forward filtering algorithm is developed to efficiently determine structural configurations under dual-state constraints. The effectiveness of the proposed approach is confirmed through two representative implementations, including dynamically switchable multifocal metalenses and multichannel holography. In addition, a progressive encoding strategy is introduced, which deliberately utilizes inter-state crosstalk to hierarchically embed optical information across material states. This compact and reconfigurable metasurface platform offers high functional density and flexible control, holding strong potential for applications in optical communication, information encryption, and adaptive display technologies.
{"title":"Dual-state six-channel polarization multiplexing in reconfigurable metasurfaces","authors":"Sujun Xie, Tianxu Jia, Xiaoyue Ma, Bingjue Li, Ruohu Zhang, Zhigang Li, Binfeng Yun, Hyeonsu Heo, Nara Jeon, Guanghao Rui, Junsuk Rho","doi":"10.1515/nanoph-2025-0403","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0403","url":null,"abstract":"Dynamically tunable metasurfaces based on phase-change materials (PCMs) have become important platforms for realizing reconfigurable optical systems. Nevertheless, achieving multiple independent functionalities within a single device, particularly under polarization multiplexing, remains difficult due to limited design flexibility. In this study, we present a metasurface design framework that reaches the theoretical maximum of six independent phase modulation functions by simultaneously controlling the polarization states and the crystallinity of the PCM. This is implemented through a pixel-extension strategy, where each nanofin functions independently in amorphous state and is reorganized into superpixels with distinct optical responses in crystalline state. To support this, a forward filtering algorithm is developed to efficiently determine structural configurations under dual-state constraints. The effectiveness of the proposed approach is confirmed through two representative implementations, including dynamically switchable multifocal metalenses and multichannel holography. In addition, a progressive encoding strategy is introduced, which deliberately utilizes inter-state crosstalk to hierarchically embed optical information across material states. This compact and reconfigurable metasurface platform offers high functional density and flexible control, holding strong potential for applications in optical communication, information encryption, and adaptive display technologies.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"51 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145472881","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 : 2025-11-09DOI: 10.1515/nanoph-2025-0488
Jiantao Ma, Shunfa Liu, Chengjie Lu, Ying Yu, Bo Chen, Jin Liu
Optical skyrmions, as structured light fields endowed with discrete topological numbers, open new opportunities for high-density encoding, robust information transport, and quantum light–matter interactions. However, most existing skyrmion generators rely on complex or bulky systems, hindering their application in scalable on-chip quantum technologies. Here, we propose a nanophotonic scheme based on semiconductor cavity quantum electrodynamics, whereby a circularly polarized quantum emitter is coupled to a concentric bullseye resonator. This configuration enables the efficient generation of single-photon Stokes vector skyrmions at subwavelength scales, as well as their high-order extensions. By exciting single-photon sources at different positions, the skyrmion number can be continuously switched between +2 and −2, while higher-order states are accessible by tuning the radius of cavity’s center disc. This strategy couples the topological dimension of skyrmions with quantum states, laying the groundwork for quantum skyrmions in on-chip topological keying and quantum readout. Our work provides a practical device architecture for integrated nanophotonic quantum topological state platforms, offering a new paradigm for topologically protected quantum communications and on-chip quantum information processing.
{"title":"Bright single-photon skyrmion sources in bullseye cavities","authors":"Jiantao Ma, Shunfa Liu, Chengjie Lu, Ying Yu, Bo Chen, Jin Liu","doi":"10.1515/nanoph-2025-0488","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0488","url":null,"abstract":"Optical skyrmions, as structured light fields endowed with discrete topological numbers, open new opportunities for high-density encoding, robust information transport, and quantum light–matter interactions. However, most existing skyrmion generators rely on complex or bulky systems, hindering their application in scalable on-chip quantum technologies. Here, we propose a nanophotonic scheme based on semiconductor cavity quantum electrodynamics, whereby a circularly polarized quantum emitter is coupled to a concentric bullseye resonator. This configuration enables the efficient generation of single-photon Stokes vector skyrmions at subwavelength scales, as well as their high-order extensions. By exciting single-photon sources at different positions, the skyrmion number can be continuously switched between +2 and −2, while higher-order states are accessible by tuning the radius of cavity’s center disc. This strategy couples the topological dimension of skyrmions with quantum states, laying the groundwork for quantum skyrmions in on-chip topological keying and quantum readout. Our work provides a practical device architecture for integrated nanophotonic quantum topological state platforms, offering a new paradigm for topologically protected quantum communications and on-chip quantum information processing.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"138 6 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145472684","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}
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