Polarization control plasmonic nanostructures provide a unique route to manipulate light–matter interactions at the nanoscale and are particularly powerful for information security applications, where polarization-encoded color images can be used for optical encryption and anticounterfeiting. Conventional plasmonic materials such as Au and Ag, however, suffer from poor thermal stability, limiting their integration into robust, CMOS-compatible devices. Here, we present a polarization-encoded color image platform based on refractory HfN plasmonic metasurfaces, which combine gold-like optical properties with exceptional hardness, compositional tunability, and superior high-temperature resilience. Periodically patterned HfN nanoantennas with widths of 200 nm exhibit well-defined localized surface plasmon resonances in the visible spectrum (628 and 564 nm) and can be selectively excited by orthogonal linear polarizations. We designed and realized a polarization-encoded color image in which distinct color channels are revealed under x- and y-polarized illumination, enabling decryption of hidden information. Under unpolarized illumination, the superposition of color channels effectively conceals the message, achieving robust optical encryption. Our results establish HfN plasmonic nanostructures as a key material platform for next-generation nanophotonics, uniquely combining gold-like optical properties with exceptional thermal robustness. Even after high-temperature annealing, HfN retains its plasmonic response, enabling reliable polarization-resolved color image encoding and decryption. This breakthrough paves the way for thermally resilient metasurfaces for secure data encryption, anticounterfeiting, and robust operation in extreme environments.
{"title":"Polarization-encoded color images for information encryption enabled by HfN refractory plasmonic metasurfaces","authors":"Yu-Cheng Chu, Tzu-Yu Peng, Chen-Yu Wang, Shyr-Shyan Yeh, Jia-Wern Chen, Yu-Jung Lu","doi":"10.1515/nanoph-2025-0502","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0502","url":null,"abstract":"Polarization control plasmonic nanostructures provide a unique route to manipulate light–matter interactions at the nanoscale and are particularly powerful for information security applications, where polarization-encoded color images can be used for optical encryption and anticounterfeiting. Conventional plasmonic materials such as Au and Ag, however, suffer from poor thermal stability, limiting their integration into robust, CMOS-compatible devices. Here, we present a polarization-encoded color image platform based on refractory HfN plasmonic metasurfaces, which combine gold-like optical properties with exceptional hardness, compositional tunability, and superior high-temperature resilience. Periodically patterned HfN nanoantennas with widths of 200 nm exhibit well-defined localized surface plasmon resonances in the visible spectrum (628 and 564 nm) and can be selectively excited by orthogonal linear polarizations. We designed and realized a polarization-encoded color image in which distinct color channels are revealed under x- and y-polarized illumination, enabling decryption of hidden information. Under unpolarized illumination, the superposition of color channels effectively conceals the message, achieving robust optical encryption. Our results establish HfN plasmonic nanostructures as a key material platform for next-generation nanophotonics, uniquely combining gold-like optical properties with exceptional thermal robustness. Even after high-temperature annealing, HfN retains its plasmonic response, enabling reliable polarization-resolved color image encoding and decryption. This breakthrough paves the way for thermally resilient metasurfaces for secure data encryption, anticounterfeiting, and robust operation in extreme environments.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"98 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145472745","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 : 2025-11-07DOI: 10.1515/nanoph-2025-0435
Ulrich Hohenester, Felix Hitzelhammer, Georg Krainer, Peter Banzer, Thomas Juffmann
We employ the concept of quantum Fisher information to optimize the focused excitation fields in coherent scattering microscopy. Our optimization goal is to achieve the best possible localization precision for small scatterers located above a glass coverslip, while keeping the intensity of the total incoming excitation fields fixed. For small numerical aperture (NA) values, the optimal fields have linear or circular polarization, and the excitation beam can be well approximated by a Gaussian one. For larger NA values, the optimal beam acquires radial polarization. We show that the high localization precision can be attributed to high field strengths at the scatterer position, and correspondingly a large number of scattered and detected photons. Finally, we evaluate the performance of the optimized beams in interferometric scattering microscopy (i scat ), and further optimize these fields for i scat localization using the concept of Fisher information.
{"title":"Optimizing the localization precision in coherent scattering microscopy using structured light","authors":"Ulrich Hohenester, Felix Hitzelhammer, Georg Krainer, Peter Banzer, Thomas Juffmann","doi":"10.1515/nanoph-2025-0435","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0435","url":null,"abstract":"We employ the concept of quantum Fisher information to optimize the focused excitation fields in coherent scattering microscopy. Our optimization goal is to achieve the best possible localization precision for small scatterers located above a glass coverslip, while keeping the intensity of the total incoming excitation fields fixed. For small numerical aperture (NA) values, the optimal fields have linear or circular polarization, and the excitation beam can be well approximated by a Gaussian one. For larger NA values, the optimal beam acquires radial polarization. We show that the high localization precision can be attributed to high field strengths at the scatterer position, and correspondingly a large number of scattered and detected photons. Finally, we evaluate the performance of the optimized beams in interferometric scattering microscopy (i <jats:sc>scat</jats:sc> ), and further optimize these fields for i <jats:sc>scat</jats:sc> localization using the concept of Fisher information.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"234 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145454959","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 : 2025-11-07DOI: 10.1515/nanoph-2025-0430
Xusheng Chen, Fanfei Meng, Kang Du, Min Lin, Luping Du
Light exhibits both spin and orbital angular momentum (SAM and OAM). These two forms of angular momentum remain independent in paraxial fields, but become coupled in confined fields through spin–orbit interactions (SOI). The SOI mechanism allows for the manipulation of SAM to generate structured light fields featuring nontrivial topological characteristics, such as optical skyrmions. Conventional OAM beams, nonetheless, carry discrete integer topological charges (TCs), leading to discrete SAM states. This discrete property poses a persistent challenge for achieving continuous control of SAM. To tackle this fundamental issue, we explored fractional orbital angular momentum (FOAM) beams, whose TCs are extended from integers to fractions, to realize continuous and precise control of SAM. A direct mathematical relationship between the fractional effective TCs of FOAM beams and the orientation distributions of the SAM vector has been derived. This theoretical prediction has been experimentally verified using our home-built near-field mapping system, by which the distinct SAM distributions of surface cosine waves regulated by FOAM beams were mapped out. As a potential application, we also devised an inverse detection method to accurately measure the fractional effective TCs of FOAM, which achieved theoretical and experimental accuracies of 10 −5 and 10 −2 , respectively. These advancements may enhance our fundamental understanding of the SOI mechanism, and hence could create novel opportunities for light field manipulation, optical communication, and other related areas.
{"title":"Spin angular momentum modulation via spin–orbit interaction in fractional orbital angular momentum beams","authors":"Xusheng Chen, Fanfei Meng, Kang Du, Min Lin, Luping Du","doi":"10.1515/nanoph-2025-0430","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0430","url":null,"abstract":"Light exhibits both spin and orbital angular momentum (SAM and OAM). These two forms of angular momentum remain independent in paraxial fields, but become coupled in confined fields through spin–orbit interactions (SOI). The SOI mechanism allows for the manipulation of SAM to generate structured light fields featuring nontrivial topological characteristics, such as optical skyrmions. Conventional OAM beams, nonetheless, carry discrete integer topological charges (TCs), leading to discrete SAM states. This discrete property poses a persistent challenge for achieving continuous control of SAM. To tackle this fundamental issue, we explored fractional orbital angular momentum (FOAM) beams, whose TCs are extended from integers to fractions, to realize continuous and precise control of SAM. A direct mathematical relationship between the fractional effective TCs of FOAM beams and the orientation distributions of the SAM vector has been derived. This theoretical prediction has been experimentally verified using our home-built near-field mapping system, by which the distinct SAM distributions of surface cosine waves regulated by FOAM beams were mapped out. As a potential application, we also devised an inverse detection method to accurately measure the fractional effective TCs of FOAM, which achieved theoretical and experimental accuracies of 10 <jats:sup>−5</jats:sup> and 10 <jats:sup>−2</jats:sup> , respectively. These advancements may enhance our fundamental understanding of the SOI mechanism, and hence could create novel opportunities for light field manipulation, optical communication, and other related areas.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"92 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145454581","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 : 2025-11-07DOI: 10.1515/nanoph-2025-0339
Junhyung Lee, Sunghyun Moon, Yongchan Park, Uijoon Park, Hansol Kim, Changhyun Kim, Minho Choi, Jin-Il Lee, Hyeon Hwang, Min-Kyo Seo, Dae-Hwan Ahn, Hojoong Jung, Hyounghan Kwon
Nonlinear signal generation requires precise control of the input polarization to satisfy phase-matching conditions. Conventional polarization management using external fiber polarization controllers or bulk wave plates increases coupling complexity and can degrade polarization fidelity and conversion efficiency in nonlinear photonic systems. Here, we demonstrate on-chip polarization control in thin-film lithium niobate nonlinear photonic circuits. Integrated polarization modulators enable real-time tuning of arbitrary input polarization states and thus provide on-demand control of nonlinear conversion in a periodically poled lithium niobate waveguide. A closed-loop feedback system, which integrates auto-compensation and automatic fiber-chip alignment routines, automatically optimizes the second-harmonic generation intensity and maintains performance over extended periods despite polarization scrambling and environmental perturbations. This integrated approach reduces coupling complexity and offers a scalable route toward fully reconfigurable nonlinear photonic systems.
{"title":"On-chip polarization management for stable nonlinear signal generation in thin-film lithium niobate","authors":"Junhyung Lee, Sunghyun Moon, Yongchan Park, Uijoon Park, Hansol Kim, Changhyun Kim, Minho Choi, Jin-Il Lee, Hyeon Hwang, Min-Kyo Seo, Dae-Hwan Ahn, Hojoong Jung, Hyounghan Kwon","doi":"10.1515/nanoph-2025-0339","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0339","url":null,"abstract":"Nonlinear signal generation requires precise control of the input polarization to satisfy phase-matching conditions. Conventional polarization management using external fiber polarization controllers or bulk wave plates increases coupling complexity and can degrade polarization fidelity and conversion efficiency in nonlinear photonic systems. Here, we demonstrate on-chip polarization control in thin-film lithium niobate nonlinear photonic circuits. Integrated polarization modulators enable real-time tuning of arbitrary input polarization states and thus provide on-demand control of nonlinear conversion in a periodically poled lithium niobate waveguide. A closed-loop feedback system, which integrates auto-compensation and automatic fiber-chip alignment routines, automatically optimizes the second-harmonic generation intensity and maintains performance over extended periods despite polarization scrambling and environmental perturbations. This integrated approach reduces coupling complexity and offers a scalable route toward fully reconfigurable nonlinear photonic systems.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"55 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455301","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 : 2025-11-06DOI: 10.1515/nanoph-2025-0331
Haiming Ye, Junhao Ge, Zhengyi Lu, Dudu Song, Jiamin Ji, Zhaoyang Peng, Shunping Zhang, Hongxing Xu
Plasmonic nanocavities have emerged as a powerful platform for extreme light confinement, enabling transformative applications in single-molecule Raman spectroscopy, ultra-sensitive sensing, strong light–matter interactions, etc. By harnessing localized surface plasmons, these nanostructures support unprecedented field enhancement, exceeding 1,000-fold in the sub-nanometer gap. However, a fundamental trade-off exists between deep sub-wavelength field localization and its efficient coupling to free-space light, limiting their practical performance. Here, we show that by balancing the electric and magnetic resonance, more than 55 % of a focused Gaussian beam can be fueled into a nanocube-on-mirror nanocavity. With few concentric gratings, the coupling efficiency can even go up to >95 % at optimal conditions. This design can work at both visible and telecommunication wavelengths and show robust tolerance to fabrication imperfections. Our work indicates that the long-standing conflict between deep field localization and efficient external coupling in plasmonic systems can be resolved by multiscale structure design, promising the use of a single metal nanoparticle for advanced nanophotonic or optoelectronic devices.
{"title":"Near-unity fueling light into a single plasmonic nanocavity","authors":"Haiming Ye, Junhao Ge, Zhengyi Lu, Dudu Song, Jiamin Ji, Zhaoyang Peng, Shunping Zhang, Hongxing Xu","doi":"10.1515/nanoph-2025-0331","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0331","url":null,"abstract":"Plasmonic nanocavities have emerged as a powerful platform for extreme light confinement, enabling transformative applications in single-molecule Raman spectroscopy, ultra-sensitive sensing, strong light–matter interactions, etc. By harnessing localized surface plasmons, these nanostructures support unprecedented field enhancement, exceeding 1,000-fold in the sub-nanometer gap. However, a fundamental trade-off exists between deep sub-wavelength field localization and its efficient coupling to free-space light, limiting their practical performance. Here, we show that by balancing the electric and magnetic resonance, more than 55 % of a focused Gaussian beam can be fueled into a nanocube-on-mirror nanocavity. With few concentric gratings, the coupling efficiency can even go up to >95 % at optimal conditions. This design can work at both visible and telecommunication wavelengths and show robust tolerance to fabrication imperfections. Our work indicates that the long-standing conflict between deep field localization and efficient external coupling in plasmonic systems can be resolved by multiscale structure design, promising the use of a single metal nanoparticle for advanced nanophotonic or optoelectronic devices.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"39 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447176","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 : 2025-11-06DOI: 10.1515/nanoph-2025-0428
Ning Liu, Qiang Liu, Yutian Lin, Zhihong Zhu, Ken Liu
In recent years, two-dimensional (2D) niobium oxide dihalides (e.g., NbOI 2 ) have garnered significant research interest in nonlinear photonics due to their prominent second-order nonlinear optical properties. Integrating these materials with high-quality-factor optical microcavities represents a crucial approach for developing high-performance on-chip nonlinear optical devices. This work demonstrates NbOI 2 -integrated silicon nitride (Si 3 N 4 ) microdisk resonators that achieve second-harmonic generation under low-power (sub-milliwatt) continuous-wave laser pumping, leveraging the superior second-order nonlinearity of NbOI 2 and the strong optical field confinement capability of Si 3 N 4 microdisks. The conversion efficiency of the device is calculated to be about 0.024 %/W. The intrinsic lack of inversion symmetry in NbOI 2 crystals avoids the laborious layer-number-dependent symmetry screening typically required for other 2D materials, while the developed van der Waals transfer technique provides a universal strategy for integrating niobium oxide dihalides with photonic microcavities. This study not only establishes a material-photon co-design strategy for on-chip nonlinear light sources but also lays a critical foundation for advancing quantum photonic chips and on-chip metrology systems.
{"title":"Second-harmonic generation in NbOI 2 -integrated silicon nitride microdisk resonators","authors":"Ning Liu, Qiang Liu, Yutian Lin, Zhihong Zhu, Ken Liu","doi":"10.1515/nanoph-2025-0428","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0428","url":null,"abstract":"In recent years, two-dimensional (2D) niobium oxide dihalides (e.g., NbOI <jats:sub>2</jats:sub> ) have garnered significant research interest in nonlinear photonics due to their prominent second-order nonlinear optical properties. Integrating these materials with high-quality-factor optical microcavities represents a crucial approach for developing high-performance on-chip nonlinear optical devices. This work demonstrates NbOI <jats:sub>2</jats:sub> -integrated silicon nitride (Si <jats:sub>3</jats:sub> N <jats:sub>4</jats:sub> ) microdisk resonators that achieve second-harmonic generation under low-power (sub-milliwatt) continuous-wave laser pumping, leveraging the superior second-order nonlinearity of NbOI <jats:sub>2</jats:sub> and the strong optical field confinement capability of Si <jats:sub>3</jats:sub> N <jats:sub>4</jats:sub> microdisks. The conversion efficiency of the device is calculated to be about 0.024 %/W. The intrinsic lack of inversion symmetry in NbOI <jats:sub>2</jats:sub> crystals avoids the laborious layer-number-dependent symmetry screening typically required for other 2D materials, while the developed van der Waals transfer technique provides a universal strategy for integrating niobium oxide dihalides with photonic microcavities. This study not only establishes a material-photon co-design strategy for on-chip nonlinear light sources but also lays a critical foundation for advancing quantum photonic chips and on-chip metrology systems.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"109 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447177","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}
The photophysical properties of single-molecule emitters are altered by nanophotonic structures such as single plasmonic nanoparticles. The intensity and spectral properties of plasmon-coupled emitters have been studied extensively, but little is known about the effect of plasmon coupling on emission polarization. Here, we examine how particle-emitter coupling modifies the polarization of single fluorophores in both experiment and simulation. We quantify degree of linear polarization using Stokes polarimetry with a polarization-sensitive camera and quantify the Stokes parameters with a single-shot acquisition without requiring additional optics in the detection path. We then perform polarization-resolved measurements of plasmon-coupled fluorescence from single-molecule emitters using an approach based on DNA-PAINT. We quantify the effect of the setup and associated noise sources on the measured Stokes parameters. We then quantify the angle of linear polarization (AoLP) and the degree of linear polarization (DoLP) for thousands of single molecules. We compare our results to a numerical model that propagates the plasmon-coupled single-molecule emission through the optical setup to yield the polarized point spread function in the camera plane. Simulations and experiments are in good agreement and shed new light on the polarization of antenna-coupled fluorophores, while it establishes single-shot polarimetry as a promising and straightforward method to quantify polarization properties at the single-molecule level.
{"title":"Single-shot Stokes polarimetry of plasmon-coupled single-molecule fluorescence","authors":"Sarojini Mahajan, Yuyang Wang, Teun A.P.M. Huijben, Rodolphe Marie, Peter Zijlstra","doi":"10.1515/nanoph-2025-0352","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0352","url":null,"abstract":"The photophysical properties of single-molecule emitters are altered by nanophotonic structures such as single plasmonic nanoparticles. The intensity and spectral properties of plasmon-coupled emitters have been studied extensively, but little is known about the effect of plasmon coupling on emission polarization. Here, we examine how particle-emitter coupling modifies the polarization of single fluorophores in both experiment and simulation. We quantify degree of linear polarization using Stokes polarimetry with a polarization-sensitive camera and quantify the Stokes parameters with a single-shot acquisition without requiring additional optics in the detection path. We then perform polarization-resolved measurements of plasmon-coupled fluorescence from single-molecule emitters using an approach based on DNA-PAINT. We quantify the effect of the setup and associated noise sources on the measured Stokes parameters. We then quantify the angle of linear polarization (AoLP) and the degree of linear polarization (DoLP) for thousands of single molecules. We compare our results to a numerical model that propagates the plasmon-coupled single-molecule emission through the optical setup to yield the polarized point spread function in the camera plane. Simulations and experiments are in good agreement and shed new light on the polarization of antenna-coupled fluorophores, while it establishes single-shot polarimetry as a promising and straightforward method to quantify polarization properties at the single-molecule level.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"230 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447180","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 : 2025-11-06DOI: 10.1515/nanoph-2025-0402
Xiang Liu, Peipeng Xu, Yingxuan Zhao, Zhen Sheng, Fuwan Gan
Programmable integrated photonic circuits are poised to drive a new revolution in information systems by synergizing with high-speed digital signals. Central to this vision is the ability to reconfigure optical signal processing for multi-functional photonic integration. Here, we design and experimentally demonstrate a thermo-optically reconfigurable adiabatic coupler monolithically integrated on a silicon photonics platform. The device combines adiabatic directional couplers with titanium nitride (TiN) micro-heaters embedded in the adiabatic transition region, enabling dynamic coupling ratio tuning via the localized thermo-optic modulation. Experimental results confirm continuous coupling ratio adjustment from 50:50 to 70:30 across 80-nm bandwidth (1,520–1,600 nm), with insertion loss kept below 0.25 dB. Leveraging its tunability, the device enables programmable spectral routing with free spectral ranges (FSR) of 20 nm and 40 nm. The proposed approach offers enhanced flexibility and scalability for high-density photonic systems, providing a promising pathway toward next-generation programmable photonic circuits and optical computing architectures.
{"title":"Continuously tunable broadband adiabatic coupler for programmable photonic processors","authors":"Xiang Liu, Peipeng Xu, Yingxuan Zhao, Zhen Sheng, Fuwan Gan","doi":"10.1515/nanoph-2025-0402","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0402","url":null,"abstract":"Programmable integrated photonic circuits are poised to drive a new revolution in information systems by synergizing with high-speed digital signals. Central to this vision is the ability to reconfigure optical signal processing for multi-functional photonic integration. Here, we design and experimentally demonstrate a thermo-optically reconfigurable adiabatic coupler monolithically integrated on a silicon photonics platform. The device combines adiabatic directional couplers with titanium nitride (TiN) micro-heaters embedded in the adiabatic transition region, enabling dynamic coupling ratio tuning via the localized thermo-optic modulation. Experimental results confirm continuous coupling ratio adjustment from 50:50 to 70:30 across 80-nm bandwidth (1,520–1,600 nm), with insertion loss kept below 0.25 dB. Leveraging its tunability, the device enables programmable spectral routing with free spectral ranges (FSR) of 20 nm and 40 nm. The proposed approach offers enhanced flexibility and scalability for high-density photonic systems, providing a promising pathway toward next-generation programmable photonic circuits and optical computing architectures.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"22 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447181","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 : 2025-11-06DOI: 10.1515/nanoph-2025-0449
Alexandra Boltasseva, Nader Engheta, Giuseppe Strangi, Dennis Couwenberg
{"title":"In honor of Federico Capasso, a visionary in nanophotonics, on the occasion of his 75th birthday","authors":"Alexandra Boltasseva, Nader Engheta, Giuseppe Strangi, Dennis Couwenberg","doi":"10.1515/nanoph-2025-0449","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0449","url":null,"abstract":"","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"22 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447606","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 : 2025-11-06DOI: 10.1515/nanoph-2025-0491
Kuntal Samanta, Sphinx J. Svensson, Sonja Franke-Arnold, Niclas Westerberg
Features of complex vector light become important in any interference effects, including scattering, diffraction, and nonlinear processes. Here, we are investigating the role of polarization-structured light in atomic state interferometers. Unlike optical or atomic path interferometers, these facilitate local interference between atomic transition amplitudes and hence the orthogonal optical polarization components driving these transitions. We develop a fully analytical description for the interaction of generalized structured light with an atomic four state system, that is, multiply connected via optical as well as magnetic transitions. Our model allows us to identify spatially dependent dark states, associated with spatially structured absorption coefficients, which are defined by the geometry of the polarization state and the magnetic field direction. We illustrate this for a range of optical beams including polarization vortices, optical skyrmions, and polarization lattices. This results in a new interpretation and an enhanced understanding of atomic state interferometry, and a versatile mechanism to modify and control optical absorption as a function of polarization and magnetic field alignment.
{"title":"Atomic state interferometry for complex vector light","authors":"Kuntal Samanta, Sphinx J. Svensson, Sonja Franke-Arnold, Niclas Westerberg","doi":"10.1515/nanoph-2025-0491","DOIUrl":"https://doi.org/10.1515/nanoph-2025-0491","url":null,"abstract":"Features of complex vector light become important in any interference effects, including scattering, diffraction, and nonlinear processes. Here, we are investigating the role of polarization-structured light in atomic state interferometers. Unlike optical or atomic path interferometers, these facilitate local interference between atomic transition amplitudes and hence the orthogonal optical polarization components driving these transitions. We develop a fully analytical description for the interaction of generalized structured light with an atomic four state system, that is, multiply connected via optical as well as magnetic transitions. Our model allows us to identify spatially dependent dark states, associated with spatially structured absorption coefficients, which are defined by the geometry of the polarization state and the magnetic field direction. We illustrate this for a range of optical beams including polarization vortices, optical skyrmions, and polarization lattices. This results in a new interpretation and an enhanced understanding of atomic state interferometry, and a versatile mechanism to modify and control optical absorption as a function of polarization and magnetic field alignment.","PeriodicalId":19027,"journal":{"name":"Nanophotonics","volume":"2 1","pages":""},"PeriodicalIF":7.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447179","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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