Pub Date : 2026-10-21DOI: 10.1021/acsphotonics.6c01473
Marcus Westhues,Roman Burkard,Thomas Geruschke,Julia Hauser,Johannes Ewering,Stefan Dreiner,Aleksandar Nesic,Anna Lena Schall-Giesecke
The integration of photonic circuits with on-chip single-photon detectors has emerged as a key enabling technology for highly scalable visible-wavelength photonic integrated circuits, underpinning advanced applications in quantum information processing and biophotonics. However, detecting weak optical signals down to the single-photon regime at specific wavelengths requires efficient interconnections between photonic waveguides and detectors. Here, we present an interconnect from silicon nitride photonic circuits to single-photon avalanche diodes (SPADs) on a standard 200 mm CMOS wafer integrated using post-CMOS integration. To realize this efficient interconnect, we optimized the interface by introducing metal reflector-assisted grating couplers for the target wavelengths 633 nm and 785 nm. To investigate the influence of the reflector on the efficiency of the interface, we conducted simulations and subsequent optimizations. In simulation, the grating-assisted interconnect achieves a coupling efficiency of 2.0 dB at 785 nm, representing a 6.4 dB improvement over the baseline design. To validate this improvement, we fabricated this structure with and without reflector and experimentally demonstrate detection of single photons at the target wavelengths. After post-CMOS integration, the utilized Fraunhofer IMS SPADs were operated at room temperature with an off-chip passive quenching circuit. Optical characterization showed an improvement by up to 4.5 dB by implementing reflectors. We show venues for improving the photon detection probability by correlating it with loss sources encountered in the fabricated devices. With these results, we demonstrate the applicability of post-CMOS integration and offer a photonic-integrated solution for detecting single photons from red to near-infrared wavelengths.
{"title":"Room-Temperature Visible-Light Single-Photon Avalanche Detection in Grating-Coupled Post-CMOS Photonic Circuits","authors":"Marcus Westhues,Roman Burkard,Thomas Geruschke,Julia Hauser,Johannes Ewering,Stefan Dreiner,Aleksandar Nesic,Anna Lena Schall-Giesecke","doi":"10.1021/acsphotonics.6c01473","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01473","url":null,"abstract":"The integration of photonic circuits with on-chip single-photon detectors has emerged as a key enabling technology for highly scalable visible-wavelength photonic integrated circuits, underpinning advanced applications in quantum information processing and biophotonics. However, detecting weak optical signals down to the single-photon regime at specific wavelengths requires efficient interconnections between photonic waveguides and detectors. Here, we present an interconnect from silicon nitride photonic circuits to single-photon avalanche diodes (SPADs) on a standard 200 mm CMOS wafer integrated using post-CMOS integration. To realize this efficient interconnect, we optimized the interface by introducing metal reflector-assisted grating couplers for the target wavelengths 633 nm and 785 nm. To investigate the influence of the reflector on the efficiency of the interface, we conducted simulations and subsequent optimizations. In simulation, the grating-assisted interconnect achieves a coupling efficiency of 2.0 dB at 785 nm, representing a 6.4 dB improvement over the baseline design. To validate this improvement, we fabricated this structure with and without reflector and experimentally demonstrate detection of single photons at the target wavelengths. After post-CMOS integration, the utilized Fraunhofer IMS SPADs were operated at room temperature with an off-chip passive quenching circuit. Optical characterization showed an improvement by up to 4.5 dB by implementing reflectors. We show venues for improving the photon detection probability by correlating it with loss sources encountered in the fabricated devices. With these results, we demonstrate the applicability of post-CMOS integration and offer a photonic-integrated solution for detecting single photons from red to near-infrared wavelengths.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"11 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-20DOI: 10.1021/acsphotonics.6c01369
Ze-Sheng Xu,Nan Cheng,Mohammed S. Elmusrati,Rohan Yadgirkar,Andrea Cataldo,Rui Wen,Govind Krishna,Jun Gao,Ali W. Elshaari
Synchronization is a widespread collective phenomenon in which coupled units with different microscopic states evolve toward a common macroscopic order. Across these systems, dissipation plays an organizing role, suppressing microscopic differences and steering coupled units toward a coherent collective state. Here, we harness engineered dissipation in a nonunitary photonic framework to synchronize light directly in the optical domain. Implementing row-stochastic transition matrices embedded in a unitary photonic network on a silicon photonic processor, we drive generic multimode optical fields toward a unique collective state with equal modal intensities and a globally locked phase─a process we term dissipation-induced phase synchronization. The synchronization rate and total optical power throughput are independently programmable, enabling control over the dissipative dynamics without compromising reconfigurability. These results recast dissipation as a functional resource and open a route to reconfigurable on-chip synchronization for classical and quantum photonic technologies.
{"title":"Programmable Non-Hermitian Synchronization of Light on a Silicon Photonic Processor","authors":"Ze-Sheng Xu,Nan Cheng,Mohammed S. Elmusrati,Rohan Yadgirkar,Andrea Cataldo,Rui Wen,Govind Krishna,Jun Gao,Ali W. Elshaari","doi":"10.1021/acsphotonics.6c01369","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01369","url":null,"abstract":"Synchronization is a widespread collective phenomenon in which coupled units with different microscopic states evolve toward a common macroscopic order. Across these systems, dissipation plays an organizing role, suppressing microscopic differences and steering coupled units toward a coherent collective state. Here, we harness engineered dissipation in a nonunitary photonic framework to synchronize light directly in the optical domain. Implementing row-stochastic transition matrices embedded in a unitary photonic network on a silicon photonic processor, we drive generic multimode optical fields toward a unique collective state with equal modal intensities and a globally locked phase─a process we term dissipation-induced phase synchronization. The synchronization rate and total optical power throughput are independently programmable, enabling control over the dissipative dynamics without compromising reconfigurability. These results recast dissipation as a functional resource and open a route to reconfigurable on-chip synchronization for classical and quantum photonic technologies.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"15 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-20DOI: 10.1021/acsphotonics.6c01514
Jiwon Kang,Nina Hong,Christopher M. Yi,Yun Su Go,Martin Thomaschewski,Hwi Je Woo,Prachi Thureja,Junghoon Jahng,Harry A. Atwater,Min Seok Jang
Barium titanate (BTO), one of the earliest reported ferroelectric materials, exhibits strong second-order nonlinearity and an ultrafast Pockels effect, making it highly attractive for photonics. However, its optical constants remain uncertain largely due to the ubiquitous ferroelectric–ferroelastic multidomain microstructure, which depolarizes and averages out the anisotropic optical response, thereby complicating conventional ellipsometric approaches. Here, we report a Kramers–Kronig-consistent complex refractive-index tensor of tetragonal BTO from the ultraviolet (190 nm) to the far-infrared (40 μm) derived from multimodal Mueller-matrix spectroscopic ellipsometry. We further quantify optical loss by incorporating transmission intensity measured over the 2–10 μm transparency window, resolving the extinction coefficient down to ∼10–5. To verify the underlying domain configuration, we performed independent structural analyses, including electron backscatter diffraction, confocal Raman microscopy, and Kelvin probe force microscopy. We then reconstruct an effective optical model for our multidomain BTO sample, formulated as a mixture of three tetragonal variants with the determined intrinsic refractive indices, to link microscopic domains to the macroscopic optical response. Our work presents a unified, experimentally cross-validated data set, enabling accurate modeling for electro-optic modulators and high-Q nanophotonic resonators without ad hoc approximations, and provides a general strategy for optical metrology of complex ferroic crystals.
{"title":"Broadband Optical Characterization of Tetragonal Barium Titanate by Mueller-Matrix Spectroscopic Ellipsometry","authors":"Jiwon Kang,Nina Hong,Christopher M. Yi,Yun Su Go,Martin Thomaschewski,Hwi Je Woo,Prachi Thureja,Junghoon Jahng,Harry A. Atwater,Min Seok Jang","doi":"10.1021/acsphotonics.6c01514","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01514","url":null,"abstract":"Barium titanate (BTO), one of the earliest reported ferroelectric materials, exhibits strong second-order nonlinearity and an ultrafast Pockels effect, making it highly attractive for photonics. However, its optical constants remain uncertain largely due to the ubiquitous ferroelectric–ferroelastic multidomain microstructure, which depolarizes and averages out the anisotropic optical response, thereby complicating conventional ellipsometric approaches. Here, we report a Kramers–Kronig-consistent complex refractive-index tensor of tetragonal BTO from the ultraviolet (190 nm) to the far-infrared (40 μm) derived from multimodal Mueller-matrix spectroscopic ellipsometry. We further quantify optical loss by incorporating transmission intensity measured over the 2–10 μm transparency window, resolving the extinction coefficient down to ∼10–5. To verify the underlying domain configuration, we performed independent structural analyses, including electron backscatter diffraction, confocal Raman microscopy, and Kelvin probe force microscopy. We then reconstruct an effective optical model for our multidomain BTO sample, formulated as a mixture of three tetragonal variants with the determined intrinsic refractive indices, to link microscopic domains to the macroscopic optical response. Our work presents a unified, experimentally cross-validated data set, enabling accurate modeling for electro-optic modulators and high-Q nanophotonic resonators without ad hoc approximations, and provides a general strategy for optical metrology of complex ferroic crystals.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"56 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Direct physical manipulation of rare-earth luminescent states is essential to overcome the chemical-response bottlenecks in optical storage. While plasmonic resonance offers a powerful platform for this purpose, the hot-electron injection and photothermal effects accompanying plasmon relaxation are inherently coupled, posing a critical challenge for their selective utilization. Here, we achieve active separation of plasmonic energy by constructing SiO2/Eu2O3/Ag and SiO2/Eu2O3/VO2/Ag heterostructures. In the direct-contact system, synergistic hot-electron injection and photothermal effects induce the Eu3+ crystal field distortion, driving the hypersensitive electric dipole transition to dominate over the magnetic dipole transition, thereby realizing wavelength-state storage with a luminescence contrast of 0.94. The introduction of a semiconducting VO2 interlayer acts as an electron barrier, blocking hot-electron injection while retaining the pure photothermal effect. This photothermal stimulation modulates the VO2/Eu2O3 interfacial defect states and V-3d electronic states, profoundly altering the Eu3+ excited-state dynamics (with the lifetime shortened from 67.79 to 1.97 μs), thereby enabling intensity-state storage. This dual-mode platform enables patterned recording alongside reversible self-erasure and nonvolatile operation. Our work offers a clear physical picture of diverting plasmonic energy channels toward low-energy, multidimensional optical storage.
{"title":"Decoupling Plasmonic Hot Electrons and Photothermal Effects at Ag/Eu2O3 Interfaces for Multimode Optical Memory","authors":"Chengyun Zhang,Huahao Chen,Tenglong Zhang,Chenjiang Wang,Wei Gao,Qingyan Han,Xuewen Yan,Mingdi Zhang,Jun Dong","doi":"10.1021/acsphotonics.6c02145","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c02145","url":null,"abstract":"Direct physical manipulation of rare-earth luminescent states is essential to overcome the chemical-response bottlenecks in optical storage. While plasmonic resonance offers a powerful platform for this purpose, the hot-electron injection and photothermal effects accompanying plasmon relaxation are inherently coupled, posing a critical challenge for their selective utilization. Here, we achieve active separation of plasmonic energy by constructing SiO2/Eu2O3/Ag and SiO2/Eu2O3/VO2/Ag heterostructures. In the direct-contact system, synergistic hot-electron injection and photothermal effects induce the Eu3+ crystal field distortion, driving the hypersensitive electric dipole transition to dominate over the magnetic dipole transition, thereby realizing wavelength-state storage with a luminescence contrast of 0.94. The introduction of a semiconducting VO2 interlayer acts as an electron barrier, blocking hot-electron injection while retaining the pure photothermal effect. This photothermal stimulation modulates the VO2/Eu2O3 interfacial defect states and V-3d electronic states, profoundly altering the Eu3+ excited-state dynamics (with the lifetime shortened from 67.79 to 1.97 μs), thereby enabling intensity-state storage. This dual-mode platform enables patterned recording alongside reversible self-erasure and nonvolatile operation. Our work offers a clear physical picture of diverting plasmonic energy channels toward low-energy, multidimensional optical storage.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"28 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-19DOI: 10.1021/acsphotonics.6c00025
Luis Felipe Morales Curiel,Aaron Kreis,Michael Krieg
Bioluminescence microscopy offers a uniquely noninvasive window into cellular dynamics, but its use has traditionally been limited by the intrinsically low brightness of luciferases. Their poor photon budget requires long exposure times, preventing faithful visualization of rapid physiological processes, especially in three dimensions. To overcome this barrier, we developed a Fourier light field microscope coupled with deep-learning-based reconstruction that achieves subsecond volumetric bioluminescence imaging, enabling direct recovery of 3D volumes from photon-limited measurements while suppressing reconstruction noise. This approach substantially mitigates the speed–resolution trade-off of conventional light field methods and bypasses the need for slow classical deconvolution priors on the depth-dependent point-spread function. We evaluate its performance by imaging 3D calcium activity in muscles and neurons of freely moving Caenorhabditis elegans and by quantifying cell dynamics within stem-cell-derived spheroids using fluorescenti acquired with fluorescence and bioluminescence contrast. Together, these results establish our framework as a practical tool for dynamic, volumetric studies of living systems.
{"title":"Seeing in the Dark: Intelligent Fourier Light Field Imaging for Bioluminescence Microscopy","authors":"Luis Felipe Morales Curiel,Aaron Kreis,Michael Krieg","doi":"10.1021/acsphotonics.6c00025","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c00025","url":null,"abstract":"Bioluminescence microscopy offers a uniquely noninvasive window into cellular dynamics, but its use has traditionally been limited by the intrinsically low brightness of luciferases. Their poor photon budget requires long exposure times, preventing faithful visualization of rapid physiological processes, especially in three dimensions. To overcome this barrier, we developed a Fourier light field microscope coupled with deep-learning-based reconstruction that achieves subsecond volumetric bioluminescence imaging, enabling direct recovery of 3D volumes from photon-limited measurements while suppressing reconstruction noise. This approach substantially mitigates the speed–resolution trade-off of conventional light field methods and bypasses the need for slow classical deconvolution priors on the depth-dependent point-spread function. We evaluate its performance by imaging 3D calcium activity in muscles and neurons of freely moving Caenorhabditis elegans and by quantifying cell dynamics within stem-cell-derived spheroids using fluorescenti acquired with fluorescence and bioluminescence contrast. Together, these results establish our framework as a practical tool for dynamic, volumetric studies of living systems.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"22 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-19DOI: 10.1021/acsphotonics.6c01763
Wei Wang,Yushi Wang,Chenxing Liu,Zhengyuan Wu,Xin Dong,Kelvin H. L. Zhang,Ning Jia,Qinglin Sai,Hongji Qi,Daoyou Guo,Shan Li,Weihua Tang,Zhilai Fang
High-speed and reliable secure optical communication remains challenging because existing bipolar photodetectors either rely on slow electrochemical processes or require wavelength-selective excitation, resulting in limited processing speed, increased system complexity, and reduced communication reliability. Here, we demonstrate a gate-programmable solar-blind β-Ga2O3 phototransistor, in which gate-controlled reconfiguration of lateral and vertical carrier transport enables reversible switching of current polarity under only a fixed 254 nm solar-blind illumination wavelength. The device exhibits a responsivity of 1.73 × 104 A/W, a detectivity above 1014 Jones, and a millisecond response time, outperforming most previously reported photoelectrochemical-type and solid-state bipolar photodetectors in terms of combined sensitivity, speed, and operational simplicity. Benefiting from the electrically programmable bipolar response, the phototransistor further realizes fast XOR logic functionality, enabling encrypted text communication and image encryption/decryption under solar-blind ultraviolet illumination. This work establishes a high-performance β-Ga2O3 optoelectronic platform integrating solar-blind photodetection, logic operation, and information security, providing a promising hardware solution for next-generation secure optical communication systems.
高速可靠的安全光通信仍然具有挑战性，因为现有的双极光电探测器要么依赖于缓慢的电化学过程，要么需要波长选择性激发，导致处理速度有限，系统复杂性增加，通信可靠性降低。在这里，我们展示了一个栅极可编程的太阳盲β-Ga2O3光电晶体管，其中栅极控制的横向和垂直载流子输运的重新配置可以在固定的254 nm太阳盲照明波长下实现电流极性的可逆切换。该器件的响应率为1.73 × 104 a /W，探测率高于1014 Jones，响应时间为毫秒，在综合灵敏度、速度和操作简单性方面优于大多数先前报道的光电化学型和固态双极光电探测器。得益于电可编程双极响应，光电晶体管进一步实现了快速异或逻辑功能，实现了在太阳盲紫外线照射下的加密文本通信和图像加密/解密。本工作建立了集日盲光探测、逻辑运算和信息安全于一体的高性能β-Ga2O3光电平台，为下一代安全光通信系统提供了一个有前景的硬件解决方案。
{"title":"Gate-Programmable Bipolar β-Ga2O3 Solar-Blind Phototransistor for Encrypted Optical Communication and Image Transmission","authors":"Wei Wang,Yushi Wang,Chenxing Liu,Zhengyuan Wu,Xin Dong,Kelvin H. L. Zhang,Ning Jia,Qinglin Sai,Hongji Qi,Daoyou Guo,Shan Li,Weihua Tang,Zhilai Fang","doi":"10.1021/acsphotonics.6c01763","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01763","url":null,"abstract":"High-speed and reliable secure optical communication remains challenging because existing bipolar photodetectors either rely on slow electrochemical processes or require wavelength-selective excitation, resulting in limited processing speed, increased system complexity, and reduced communication reliability. Here, we demonstrate a gate-programmable solar-blind β-Ga2O3 phototransistor, in which gate-controlled reconfiguration of lateral and vertical carrier transport enables reversible switching of current polarity under only a fixed 254 nm solar-blind illumination wavelength. The device exhibits a responsivity of 1.73 × 104 A/W, a detectivity above 1014 Jones, and a millisecond response time, outperforming most previously reported photoelectrochemical-type and solid-state bipolar photodetectors in terms of combined sensitivity, speed, and operational simplicity. Benefiting from the electrically programmable bipolar response, the phototransistor further realizes fast XOR logic functionality, enabling encrypted text communication and image encryption/decryption under solar-blind ultraviolet illumination. This work establishes a high-performance β-Ga2O3 optoelectronic platform integrating solar-blind photodetection, logic operation, and information security, providing a promising hardware solution for next-generation secure optical communication systems.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"25 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Disordered coatings based on silica microspheres provide a scalable and robust platform for passive daytime radiative cooling. While particle-size optimization is often considered critical for enhancing solar scattering, the role of microsphere diameter once a coating operates in the multiple-scattering regime remains unclear. Here, we characterize the radiative cooling performance of disordered, multiply scattering photonic glass coatings with diameters ranging from 2 to 8 μm, deposited on a highly reflective substrate. Despite measurable differences in microscopic scattering properties, both the spectral radiative response and the net cooling performance are robust to variations in particle diameter within the investigated range. Outdoor thermal measurements reveal nearly identical steady-state temperature reductions across the full size range. These results identify this robustness as a property of the complete coating–substrate architecture: in the solar range, multiple scattering and the reflective substrate act together to maintain high reflectance, while in the mid-infrared range, the response is dominated by the intrinsic Si–O absorption of the silica layer. This robustness enables microsphere size to be selected based on surface chemistry or processing constraints without compromising cooling performance.
{"title":"Robust Radiative Cooling in Functionalizable Silica Microsphere Paints","authors":"Jorge Burgos,José Rodrigo Magana,Ares Lladós,Javier Pascualena Ferré,Sara Núñez-Sánchez,Juliana Jaramillo Fernández,Cefe López,Pedro David García","doi":"10.1021/acsphotonics.6c01355","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01355","url":null,"abstract":"Disordered coatings based on silica microspheres provide a scalable and robust platform for passive daytime radiative cooling. While particle-size optimization is often considered critical for enhancing solar scattering, the role of microsphere diameter once a coating operates in the multiple-scattering regime remains unclear. Here, we characterize the radiative cooling performance of disordered, multiply scattering photonic glass coatings with diameters ranging from 2 to 8 μm, deposited on a highly reflective substrate. Despite measurable differences in microscopic scattering properties, both the spectral radiative response and the net cooling performance are robust to variations in particle diameter within the investigated range. Outdoor thermal measurements reveal nearly identical steady-state temperature reductions across the full size range. These results identify this robustness as a property of the complete coating–substrate architecture: in the solar range, multiple scattering and the reflective substrate act together to maintain high reflectance, while in the mid-infrared range, the response is dominated by the intrinsic Si–O absorption of the silica layer. This robustness enables microsphere size to be selected based on surface chemistry or processing constraints without compromising cooling performance.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"81 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-17DOI: 10.1021/acsphotonics.6c01729
Alexander Neuhaus,Pascal Dreher,Philipp Gessler,Bettina Frank,Timothy J. Davis,Harald Giessen,Karin Everschor-Sitte,Frank-J. Meyer zu Heringdorf
Abstract Topological concepts are frequently used to describe structured optical fields, including plasmonic near fields. Topological descriptions in terms of skyrmion numbers implicitly assume the compactness of the underlying manifold. While this concept works for constrained fields due to inherent integration boundaries, compactness is usually not fulfilled in extended optical fields. Here, we use time-resolved polarimetric photoemission microscopy to determine the electric field vectors of a surface plasmon polariton nanofocus on Au(111) with deep sub-wavelength spatial and sub-fs temporal resolution. The surface plasmon polaritons were excited with circularly polarized light at an Archimedean spiral that was milled into the Au surface by a focused ion beam. The full vectorial field information provided by polarimetric PEEM allows for a spatiotemporal analysis of the skyrmion number of the field texture. At a fixed time, the skyrmion number oscillates as a function of the radius. Furthermore, the skyrmion number oscillates in time. The experimental findings are compared to analytical calculations that lead to the same conclusion: a global skyrmion number cannot be assigned in such non-compact fields. Our results reveal the limitations of the skyrmion number for optical fields and motivate the search for new topological invariants suited for optical fields.
{"title":"Analysis of\u0000the Topology of a Plasmonic Target-Skyrmion\u0000Texture","authors":"Alexander Neuhaus,Pascal Dreher,Philipp Gessler,Bettina Frank,Timothy J. Davis,Harald Giessen,Karin Everschor-Sitte,Frank-J. Meyer zu Heringdorf","doi":"10.1021/acsphotonics.6c01729","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01729","url":null,"abstract":"Abstract Topological concepts are frequently used to describe structured optical fields, including plasmonic near fields. Topological descriptions in terms of skyrmion numbers implicitly assume the compactness of the underlying manifold. While this concept works for constrained fields due to inherent integration boundaries, compactness is usually not fulfilled in extended optical fields. Here, we use time-resolved polarimetric photoemission microscopy to determine the electric field vectors of a surface plasmon polariton nanofocus on Au(111) with deep sub-wavelength spatial and sub-fs temporal resolution. The surface plasmon polaritons were excited with circularly polarized light at an Archimedean spiral that was milled into the Au surface by a focused ion beam. The full vectorial field information provided by polarimetric PEEM allows for a spatiotemporal analysis of the skyrmion number of the field texture. At a fixed time, the skyrmion number oscillates as a function of the radius. Furthermore, the skyrmion number oscillates in time. The experimental findings are compared to analytical calculations that lead to the same conclusion: a global skyrmion number cannot be assigned in such non-compact fields. Our results reveal the limitations of the skyrmion number for optical fields and motivate the search for new topological invariants suited for optical fields.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"1 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-16DOI: 10.1021/acsphotonics.6c01318
Johannes Bürger,Erika Cortese,Simone Di Muzio,Daniele Sanvitto,Simone De Liberato,Dario Ballarini
Abstract Strong light–matter coupling in optical waveguides provides a versatile platform for engineering hybrid polaritonic modes and their dispersion. Here, we investigate multimode exciton–photon coupling in visible semiconductor waveguides supporting several transverse electric modes. Using rigorous coupled-wave analysis combined with a coupled-oscillator model, we show that the photonic band structure can be engineered across a range of regimes, from conventional multimode strong coupling to the superstrong coupling regime, where the Rabi coupling becomes comparable to the spacing between adjacent photonic modes. In the latter regime, hybridization between orthogonal electromagnetic modes is enabled by restricting the active material to a subregion of the mode volume where the photonic modes exhibit strong mutual overlap. This breaking of the orthogonality leads to polaritonic branches whose composition can be tuned among several photonic modes and the exciton. We demonstrate that small shifts of the exciton resonance produce pronounced changes in the propagation constants of different polariton branches, enabling exciton-controlled phase modulation through modal interference and, in the superstrong coupling regime, direct modal switching across a continuous S-shaped dispersion. The resulting figures of merit predict π phase shifts for exciton energy shifts of only a few meV over propagation lengths of tens of micrometers, while larger shifts are still required for mode switching. These results establish multimode waveguide polaritons as a versatile platform spanning multiple coupling regimes, for compact phase and intensity control in integrated photonic architectures.
{"title":"Exciton-Tunable\u0000Phase Control and Superstrong Coupling\u0000through Multimode Polariton Engineering in Planar Waveguides","authors":"Johannes Bürger,Erika Cortese,Simone Di Muzio,Daniele Sanvitto,Simone De Liberato,Dario Ballarini","doi":"10.1021/acsphotonics.6c01318","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01318","url":null,"abstract":"Abstract Strong light–matter coupling in optical waveguides provides a versatile platform for engineering hybrid polaritonic modes and their dispersion. Here, we investigate multimode exciton–photon coupling in visible semiconductor waveguides supporting several transverse electric modes. Using rigorous coupled-wave analysis combined with a coupled-oscillator model, we show that the photonic band structure can be engineered across a range of regimes, from conventional multimode strong coupling to the superstrong coupling regime, where the Rabi coupling becomes comparable to the spacing between adjacent photonic modes. In the latter regime, hybridization between orthogonal electromagnetic modes is enabled by restricting the active material to a subregion of the mode volume where the photonic modes exhibit strong mutual overlap. This breaking of the orthogonality leads to polaritonic branches whose composition can be tuned among several photonic modes and the exciton. We demonstrate that small shifts of the exciton resonance produce pronounced changes in the propagation constants of different polariton branches, enabling exciton-controlled phase modulation through modal interference and, in the superstrong coupling regime, direct modal switching across a continuous S-shaped dispersion. The resulting figures of merit predict π phase shifts for exciton energy shifts of only a few meV over propagation lengths of tens of micrometers, while larger shifts are still required for mode switching. These results establish multimode waveguide polaritons as a versatile platform spanning multiple coupling regimes, for compact phase and intensity control in integrated photonic architectures.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"482 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-10-15DOI: 10.1021/acsphotonics.6c01984
Tanvir M. Mahim,Md Nahin Islam,M. Mosaddequr Rahman,Abu S. M. Mohsin
Abstract Identifying which candidate sites on a solid-state sample are single-photon emitters requires a Hanbury Brown–Twiss (HBT) measurement of the second-order correlation function g(2)(τ), which is slow because photon coincidences accumulate at a rate proportional to the square of the detected count rate. We examine how much of this time can be saved by deciding while the coincidences are still accumulating and by adapting the exposure of each site. A spiking neural network reads the coincidence record in short time slices and updates, after every slice, its estimate of the probability that the site hosts a single emitter; a reinforcement-learning controller decides, site by site, whether to expose longer, certify, or reject; and a graph that encodes the electronic level structure of each emitter class conditions one estimator on the class being measured. All components are trained on simulated data from a standard three-level photon-counting model, which we validate against the exact master-equation solution before use. In simulation, the event-driven estimator reaches 90% balanced accuracy with 6 times less acquisition time than a multistart least-squares fit, typically committing to a decision 312 ms into a 1 s exposure, and adaptive exposure screens simulated 48-site fields 1.7 times faster than fixed-dwell scanning at matched precision and recall. Applied without retraining to published experimental HBT data from an InGaAs/GaAs quantum dot, a network trained only on simulated pulsed-excitation histograms estimates g(2)(0) from 30 s records with half the error of peak-area analysis of the same records. The closed-loop results are obtained in simulation only. The code, data, and trained models are openly available.
{"title":"Closed-Loop,\u0000Event-Driven Machine Learning for Autonomous\u0000Triage of Single-Photon Emitters","authors":"Tanvir M. Mahim,Md Nahin Islam,M. Mosaddequr Rahman,Abu S. M. Mohsin","doi":"10.1021/acsphotonics.6c01984","DOIUrl":"https://doi.org/10.1021/acsphotonics.6c01984","url":null,"abstract":"Abstract Identifying which candidate sites on a solid-state sample are single-photon emitters requires a Hanbury Brown–Twiss (HBT) measurement of the second-order correlation function g(2)(τ), which is slow because photon coincidences accumulate at a rate proportional to the square of the detected count rate. We examine how much of this time can be saved by deciding while the coincidences are still accumulating and by adapting the exposure of each site. A spiking neural network reads the coincidence record in short time slices and updates, after every slice, its estimate of the probability that the site hosts a single emitter; a reinforcement-learning controller decides, site by site, whether to expose longer, certify, or reject; and a graph that encodes the electronic level structure of each emitter class conditions one estimator on the class being measured. All components are trained on simulated data from a standard three-level photon-counting model, which we validate against the exact master-equation solution before use. In simulation, the event-driven estimator reaches 90% balanced accuracy with 6 times less acquisition time than a multistart least-squares fit, typically committing to a decision 312 ms into a 1 s exposure, and adaptive exposure screens simulated 48-site fields 1.7 times faster than fixed-dwell scanning at matched precision and recall. Applied without retraining to published experimental HBT data from an InGaAs/GaAs quantum dot, a network trained only on simulated pulsed-excitation histograms estimates g(2)(0) from 30 s records with half the error of peak-area analysis of the same records. The closed-loop results are obtained in simulation only. The code, data, and trained models are openly available.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"20 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149210036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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