Pub Date : 2025-07-09DOI: 10.1021/acsphotonics.5c00964
Seokheon Kim, Sangwoon Yoon
Understanding the generation and transfer of hot carriers in gold nanoparticles (AuNPs) is critical for advancing plasmonic photocatalysis and photovoltaics. Hot carriers are produced via nonradiative plasmon decay, yet the size dependence of their generation and the spatial range of their transfer remain underexplored. Here, we employ photoelectrochemical (PEC) methods to directly quantify the generation and transfer efficiencies of hot carriers in AuNPs. Size-controlled gold nanospheres (AuNSs) with diameters of 20, 32, 56, 74, and 98 nm are immobilized on ITO electrodes. Upon 532 nm laser excitation in a citrate-containing solution, hot holes oxidize citrate, and the resulting electron accumulation is measured via a photocurrent or open-circuit potential. We find that the hot carrier generation efficiency per absorbed photon decreases with an increasing AuNS size, exhibiting an inverse-square dependence on the AuNS diameter. To evaluate distance-dependent transfer efficiency, we introduce alkanethiol self-assembled monolayers (SAMs) of varying lengths onto the AuNS surfaces. The photocurrent decays exponentially with SAM thickness, revealing the spatial attenuation of the hot hole transfer. Our findings demonstrate the utility of PEC methods for probing plasmonic hot carriers and provide direct evidence for both size- and distance-dependent efficiencies.
{"title":"Photoelectrochemical Probing of Hot Carrier Generation and Transfer in Gold Nanospheres","authors":"Seokheon Kim, Sangwoon Yoon","doi":"10.1021/acsphotonics.5c00964","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00964","url":null,"abstract":"Understanding the generation and transfer of hot carriers in gold nanoparticles (AuNPs) is critical for advancing plasmonic photocatalysis and photovoltaics. Hot carriers are produced via nonradiative plasmon decay, yet the size dependence of their generation and the spatial range of their transfer remain underexplored. Here, we employ photoelectrochemical (PEC) methods to directly quantify the generation and transfer efficiencies of hot carriers in AuNPs. Size-controlled gold nanospheres (AuNSs) with diameters of 20, 32, 56, 74, and 98 nm are immobilized on ITO electrodes. Upon 532 nm laser excitation in a citrate-containing solution, hot holes oxidize citrate, and the resulting electron accumulation is measured via a photocurrent or open-circuit potential. We find that the hot carrier generation efficiency per absorbed photon decreases with an increasing AuNS size, exhibiting an inverse-square dependence on the AuNS diameter. To evaluate distance-dependent transfer efficiency, we introduce alkanethiol self-assembled monolayers (SAMs) of varying lengths onto the AuNS surfaces. The photocurrent decays exponentially with SAM thickness, revealing the spatial attenuation of the hot hole transfer. Our findings demonstrate the utility of PEC methods for probing plasmonic hot carriers and provide direct evidence for both size- and distance-dependent efficiencies.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"21 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144586798","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}
GaN-based materials have recently attracted continuous interest in optoelectronic and photocatalytic applications; however, the role of surface built-in electric fields, a critical determinant of carrier dynamics and device performance, remains poorly understood. Herein, we take GaN films as an example to explore the built-in field and charge separation dynamics at various GaN surfaces using transient reflection (TR) spectroscopy. Unlike undoped GaN films without a built-in field, both the TR spectra of n-type and p-type doped GaN films exhibit remarkable Franz–Keldysh oscillation above the bandgap, confirming the presence of an intrinsic built-in field. Driven by the built-in field, photogenerated carriers at the doped GaN surfaces undergo ultrafast charge separation within ∼4.0 ps, achieving a remarkably prolonged carrier lifetime of up to 13.9 μs, which is 4 orders of magnitude longer than that in undoped GaN. Furthermore, the charge separation dynamics in the n-GaN film is quantitatively analyzed using a one-dimensional drift-diffusion model, yielding an intrinsic built-in field of ∼37 kV/cm. Our findings might offer new insights into the rational design of efficient GaN-based photocatalytic systems and optoelectronic devices.
{"title":"Built-In Electric Field for Efficient Charge Separation and Prolonged Carrier Lifetime at the Doped GaN Surface","authors":"Shengli Zhao, Jing Leng, Xianchang Yan, Fengke Sun, Peng Xu, Shengye Jin, Wenming Tian","doi":"10.1021/acsphotonics.5c00868","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00868","url":null,"abstract":"GaN-based materials have recently attracted continuous interest in optoelectronic and photocatalytic applications; however, the role of surface built-in electric fields, a critical determinant of carrier dynamics and device performance, remains poorly understood. Herein, we take GaN films as an example to explore the built-in field and charge separation dynamics at various GaN surfaces using transient reflection (TR) spectroscopy. Unlike undoped GaN films without a built-in field, both the TR spectra of n-type and p-type doped GaN films exhibit remarkable Franz–Keldysh oscillation above the bandgap, confirming the presence of an intrinsic built-in field. Driven by the built-in field, photogenerated carriers at the doped GaN surfaces undergo ultrafast charge separation within ∼4.0 ps, achieving a remarkably prolonged carrier lifetime of up to 13.9 μs, which is 4 orders of magnitude longer than that in undoped GaN. Furthermore, the charge separation dynamics in the n-GaN film is quantitatively analyzed using a one-dimensional drift-diffusion model, yielding an intrinsic built-in field of ∼37 kV/cm. Our findings might offer new insights into the rational design of efficient GaN-based photocatalytic systems and optoelectronic devices.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"690 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144586799","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 : 2025-07-03DOI: 10.1021/acsphotonics.5c00554
Rajeev Dwivedi, Huu Dat Nguyen, Sergio Sao Joao, Anne-Magali Seydoux-Guillaume, Thirunaukkarasu Kuppan, Ciro D’Amico, Guillaume Kermouche, Razvan Stoian
Understanding matter transformation under light enables ultrafast 3D laser structuring to attain precise control down to the nanoscale. This is challenging for hard crystals given their mechanical resistance; nonetheless, it is key in structurally designing matter, pendling between crystalline and amorphous phases. The particular time evolution of structural and morphological changes can pinpoint either dynamics related to shock compaction or to thermal relaxation with phase transition. We report quantified the time-resolved dynamics of laser modifications induced by nondiffractive ultrafast laser beams in bulk sapphire using qualitative and quantitative phase-contrast microscopy to link optical changes to thermodynamic and structural evolutions. The final morphological changes of irradiated structures are revealed by high-resolution electron microscopy. Observations confirm that Bessel pulse irradiation transforms the pristine crystalline structure into a homogeneous amorphous phase in tens of ns, via the passage through a liquid phase nucleated at the early stages of the process. This ns-lived liquid phase is subject to cavitation at higher energy concentrations on the cooling phase (100 ns), facilitating nanoscale void fabrication with high aspect ratios. The outcomes strongly support bulk modification without shock assistance, governed instead by thermal relaxation. This determines a robust path for extreme laser structuring down to the nanoscale.
{"title":"Dynamic Ultrafast Laser-Induced Structural Changes and Extreme Nanostructuring in Hard Dielectric Materials","authors":"Rajeev Dwivedi, Huu Dat Nguyen, Sergio Sao Joao, Anne-Magali Seydoux-Guillaume, Thirunaukkarasu Kuppan, Ciro D’Amico, Guillaume Kermouche, Razvan Stoian","doi":"10.1021/acsphotonics.5c00554","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00554","url":null,"abstract":"Understanding matter transformation under light enables ultrafast 3D laser structuring to attain precise control down to the nanoscale. This is challenging for hard crystals given their mechanical resistance; nonetheless, it is key in structurally designing matter, pendling between crystalline and amorphous phases. The particular time evolution of structural and morphological changes can pinpoint either dynamics related to shock compaction or to thermal relaxation with phase transition. We report quantified the time-resolved dynamics of laser modifications induced by nondiffractive ultrafast laser beams in bulk sapphire using qualitative and quantitative phase-contrast microscopy to link optical changes to thermodynamic and structural evolutions. The final morphological changes of irradiated structures are revealed by high-resolution electron microscopy. Observations confirm that Bessel pulse irradiation transforms the pristine crystalline structure into a homogeneous amorphous phase in tens of ns, via the passage through a liquid phase nucleated at the early stages of the process. This ns-lived liquid phase is subject to cavitation at higher energy concentrations on the cooling phase (100 ns), facilitating nanoscale void fabrication with high aspect ratios. The outcomes strongly support bulk modification without shock assistance, governed instead by thermal relaxation. This determines a robust path for extreme laser structuring down to the nanoscale.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"150 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144547624","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 : 2025-07-03DOI: 10.1021/acsphotonics.5c00198
He Gao, Alekhya Ghosh, Arghadeep Pal, Keyi Zhong, Haochen Yan, Hao Zhang, Yongyong Zhuang, Ke Xu, Lu Sun, Shuangyou Zhang, Pascal Del’Haye, Wengang Bi, Hon Ki Tsang, Yaojing Zhang
The generation and control of multidimensional optical fields play a crucial role in advancing applications such as optical communications, sensing, information encoding, and imaging, by maximizing the utilization of optical degrees of freedom and enabling multiple optical channels. Optical lasers are fundamental to these applications as the primary sources of optical fields. However, previous work mainly focused on realizing light sources based on fundamental modes, leaving higher-order modes underutilized. Here, we propose an approach for generating and controlling an on-chip higher-order-mode light source from Raman lasing. We chose the fourth-order mode as an example and generated the fourth-order mode lasing using a compact, high-quality multimode silicon racetrack resonator. The multimode racetrack resonator has a compact footprint of 0.13 mm2 using two adiabatic bends and exhibits a high-quality factor of over 1 × 106. The lasing threshold was measured as 0.6 mW. Finally, we show that controlling the higher-order-mode lasing enables mode-switching behavior, which can find potential applications in high-resolution optical systems and quantum optics.
{"title":"Generation and Control of Higher-Order-Mode Lasers in Multimode Silicon Resonators","authors":"He Gao, Alekhya Ghosh, Arghadeep Pal, Keyi Zhong, Haochen Yan, Hao Zhang, Yongyong Zhuang, Ke Xu, Lu Sun, Shuangyou Zhang, Pascal Del’Haye, Wengang Bi, Hon Ki Tsang, Yaojing Zhang","doi":"10.1021/acsphotonics.5c00198","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00198","url":null,"abstract":"The generation and control of multidimensional optical fields play a crucial role in advancing applications such as optical communications, sensing, information encoding, and imaging, by maximizing the utilization of optical degrees of freedom and enabling multiple optical channels. Optical lasers are fundamental to these applications as the primary sources of optical fields. However, previous work mainly focused on realizing light sources based on fundamental modes, leaving higher-order modes underutilized. Here, we propose an approach for generating and controlling an on-chip higher-order-mode light source from Raman lasing. We chose the fourth-order mode as an example and generated the fourth-order mode lasing using a compact, high-quality multimode silicon racetrack resonator. The multimode racetrack resonator has a compact footprint of 0.13 mm<sup>2</sup> using two adiabatic bends and exhibits a high-quality factor of over 1 × 10<sup>6</sup>. The lasing threshold was measured as 0.6 mW. Finally, we show that controlling the higher-order-mode lasing enables mode-switching behavior, which can find potential applications in high-resolution optical systems and quantum optics.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"48 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144547623","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 : 2025-07-02DOI: 10.1021/acsphotonics.5c00679
Juozas Dudutis, Aleksandras Kondratas, Paulius Gečys
Intra-volume glass scribing for cutting is one of the most advanced applications of nondiffractive laser beams. However, ever-growing requirements from the industry for complexity, miniaturization, and quality of fabricated parts have pushed the technology forward. Most of the methods developed to improve glass scribing rely on spatial and temporal pulsed beam shaping. As another degree of freedom to manipulate light, polarization has received little attention so far. In this work, we investigate the effect of linear and circular polarizations on the volumetric modification and scribing of soda-lime glass using a zero-order Bessel beam in the MHz burst regime. We demonstrate that at a certain burst energy, transverse microcracks align with the linear polarization orientation. Furthermore, we show that the polarization state affects the modified glass separation, processing speed, efficiency, and quality.
{"title":"Polarization-Dependent Laser-Assisted Cutting of Glass Using a Nondiffractive Beam in the MHz Burst Regime","authors":"Juozas Dudutis, Aleksandras Kondratas, Paulius Gečys","doi":"10.1021/acsphotonics.5c00679","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00679","url":null,"abstract":"Intra-volume glass scribing for cutting is one of the most advanced applications of nondiffractive laser beams. However, ever-growing requirements from the industry for complexity, miniaturization, and quality of fabricated parts have pushed the technology forward. Most of the methods developed to improve glass scribing rely on spatial and temporal pulsed beam shaping. As another degree of freedom to manipulate light, polarization has received little attention so far. In this work, we investigate the effect of linear and circular polarizations on the volumetric modification and scribing of soda-lime glass using a zero-order Bessel beam in the MHz burst regime. We demonstrate that at a certain burst energy, transverse microcracks align with the linear polarization orientation. Furthermore, we show that the polarization state affects the modified glass separation, processing speed, efficiency, and quality.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"10 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144533678","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 : 2025-07-01DOI: 10.1021/acsphotonics.5c00826
Vanna Pugliese, Elena Nieto Hernández, Emilio Corte, Marco Govoni, Sviatoslav Ditalia Tchernij, Paolo Olivero, Jacopo Forneris
Split-vacancy color centers in diamonds are promising solid-state platforms for the implementation of photonic quantum technologies. These luminescent defects are commonly fabricated upon low-energy ion implantation and subsequent thermal annealing. Their technological uptake will require the availability of reliable methods for the controlled, large-scale production of localized individual photon emitters. This task is partially achieved by controlled ion implantation to introduce selected impurities in the host material and requires the development of challenging beam focusing or collimation procedures coupled with single-ion detection techniques. We report on the protocol for the direct optical activation of split-vacancy color centers in diamond via localized processing with a continuous-wave laser at mW optical powers. We demonstrate the activation of photoluminescent Mg- and Sn-related centers at both the ensemble and single-photon emitter levels in ion-implanted, high-purity diamond crystals without further thermal processing. The proposed lithographic method enables the activation of individual color centers at specific positions of a large-area sample by means of a relatively inexpensive equipment offering real-time, in situ monitoring of the process.
{"title":"Photoactivation of Color Centers Induced by CW Laser Irradiation in Ion-Implanted Diamond","authors":"Vanna Pugliese, Elena Nieto Hernández, Emilio Corte, Marco Govoni, Sviatoslav Ditalia Tchernij, Paolo Olivero, Jacopo Forneris","doi":"10.1021/acsphotonics.5c00826","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00826","url":null,"abstract":"Split-vacancy color centers in diamonds are promising solid-state platforms for the implementation of photonic quantum technologies. These luminescent defects are commonly fabricated upon low-energy ion implantation and subsequent thermal annealing. Their technological uptake will require the availability of reliable methods for the controlled, large-scale production of localized individual photon emitters. This task is partially achieved by controlled ion implantation to introduce selected impurities in the host material and requires the development of challenging beam focusing or collimation procedures coupled with single-ion detection techniques. We report on the protocol for the direct optical activation of split-vacancy color centers in diamond via localized processing with a continuous-wave laser at mW optical powers. We demonstrate the activation of photoluminescent Mg- and Sn-related centers at both the ensemble and single-photon emitter levels in ion-implanted, high-purity diamond crystals without further thermal processing. The proposed lithographic method enables the activation of individual color centers at specific positions of a large-area sample by means of a relatively inexpensive equipment offering real-time, in situ monitoring of the process.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"11 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144533679","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 : 2025-07-01DOI: 10.1021/acsphotonics.5c00865
Yisu Kim, Taesoo Lee, Beomsoo Chun, Jaekwon Kim, Jeonghun Kwak
Quantum-dot (QD)-based light-emitting diodes (QLEDs) are widely recognized as promising next-generation display technologies due to their high efficiency, narrow emission bandwidths, and wide color gamut. However, conventional metal oxide-based electron transport layers (ETLs), such as those based on ZnO nanoparticles (NPs), suffer from intrinsic instability associated with oxygen vacancies. These defects often lead to charge imbalance, exciton quenching, and device degradation under electrical stress. To overcome these limitations, we incorporate wide band gap ZnS NPs with excellent optoelectronic properties, including high optical transparency, low defect density, and strong chemical stability, into ZnO NP-based ETLs in InP-based QLEDs. By optimizing the ZnS NP content, we successfully modulate the conduction band level, suppress exciton quenching at the ETL/QD interface, and achieve improved charge balance. As a result, InP-based QLEDs employing the ZnO:ZnS nanocomposite ETL exhibit a 1.7-fold increase in external quantum efficiency and a 1.8-fold improvement in power efficiency, along with a substantial reduction in efficiency roll-off. Furthermore, under electrical aging conditions, the nanocomposite ETL effectively mitigates electron overaccumulation and interfacial degradation, resulting in a 4.6-fold extension in operational lifetime. This work offers a practical and scalable approach to ETL engineering in QLEDs. It also provides new insights into the control of charge transport and exciton dynamics for the development of more stable and efficient optoelectronic devices.
{"title":"Improved Efficiency and Operational Lifetime in InP-Based Quantum-Dot Light-Emitting Diodes Using a ZnO:ZnS Nanocomposite Electron Transport Layer","authors":"Yisu Kim, Taesoo Lee, Beomsoo Chun, Jaekwon Kim, Jeonghun Kwak","doi":"10.1021/acsphotonics.5c00865","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00865","url":null,"abstract":"Quantum-dot (QD)-based light-emitting diodes (QLEDs) are widely recognized as promising next-generation display technologies due to their high efficiency, narrow emission bandwidths, and wide color gamut. However, conventional metal oxide-based electron transport layers (ETLs), such as those based on ZnO nanoparticles (NPs), suffer from intrinsic instability associated with oxygen vacancies. These defects often lead to charge imbalance, exciton quenching, and device degradation under electrical stress. To overcome these limitations, we incorporate wide band gap ZnS NPs with excellent optoelectronic properties, including high optical transparency, low defect density, and strong chemical stability, into ZnO NP-based ETLs in InP-based QLEDs. By optimizing the ZnS NP content, we successfully modulate the conduction band level, suppress exciton quenching at the ETL/QD interface, and achieve improved charge balance. As a result, InP-based QLEDs employing the ZnO:ZnS nanocomposite ETL exhibit a 1.7-fold increase in external quantum efficiency and a 1.8-fold improvement in power efficiency, along with a substantial reduction in efficiency roll-off. Furthermore, under electrical aging conditions, the nanocomposite ETL effectively mitigates electron overaccumulation and interfacial degradation, resulting in a 4.6-fold extension in operational lifetime. This work offers a practical and scalable approach to ETL engineering in QLEDs. It also provides new insights into the control of charge transport and exciton dynamics for the development of more stable and efficient optoelectronic devices.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"11 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144533680","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 : 2025-06-25DOI: 10.1021/acsphotonics.5c01198
Serkan Arslan, Micha Kappel, Adrià Canós Valero, Thi Thu Huong Tran, Julian Karst, Philipp Christ, Ulrich Hohenester, Thomas Weiss, Harald Giessen, Mario Hentschel
Traditional nanophotonic sensing schemes utilize evanescent fields in dielectric or metallic nanoparticles, which confine far-field radiation in dispersive and lossy media. Apart from the lack of a well-defined sensing volume, these structures suffer from the generally limited access to the modal field, which is one key aspect for sensing performance. Recently, a novel strategy for dielectric nanophotonics has been demonstrated, namely, the resonant confinement of light in air. So-called Mie voids created in high-index dielectric host materials support localized resonant modes with exceptional properties. In particular, these structures benefit from the full access to the modal field confined strongly inside the void. We utilize these Mie voids for refractive index sensing in single voids with volumes down to 100 attoliters and sensitivities on the order of 400 nm per refractive index unit. Taking the noise of our measurements into account, we demonstrate detection of refractive index changes as small as 1 × 10–3 in a defined volume of just 390 attoliters. The combination of our Mie void sensor platform with appropriate surface functionalization will even enable specificity to biological or other analytes of smallest volumes while maintaining said sensitivity.
{"title":"Attoliter Mie Void Sensing","authors":"Serkan Arslan, Micha Kappel, Adrià Canós Valero, Thi Thu Huong Tran, Julian Karst, Philipp Christ, Ulrich Hohenester, Thomas Weiss, Harald Giessen, Mario Hentschel","doi":"10.1021/acsphotonics.5c01198","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c01198","url":null,"abstract":"Traditional nanophotonic sensing schemes utilize evanescent fields in dielectric or metallic nanoparticles, which confine far-field radiation in dispersive and lossy media. Apart from the lack of a well-defined sensing volume, these structures suffer from the generally limited access to the modal field, which is one key aspect for sensing performance. Recently, a novel strategy for dielectric nanophotonics has been demonstrated, namely, the resonant confinement of light in air. So-called Mie voids created in high-index dielectric host materials support localized resonant modes with exceptional properties. In particular, these structures benefit from the full access to the modal field confined strongly inside the void. We utilize these Mie voids for refractive index sensing in single voids with volumes down to 100 attoliters and sensitivities on the order of 400 nm per refractive index unit. Taking the noise of our measurements into account, we demonstrate detection of refractive index changes as small as 1 × 10<sup>–3</sup> in a defined volume of just 390 attoliters. The combination of our Mie void sensor platform with appropriate surface functionalization will even enable specificity to biological or other analytes of smallest volumes while maintaining said sensitivity.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"26 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144479354","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}
Neuromorphic computing stands out as a highly competitive computing paradigm capable of overcoming the bottlenecks inherent in von Neumann architectures. The spiking convolutional neural network (SCNN) is a prominent type of model within the realm of neuromorphic computing. Adapting SCNNs to photonic neuromorphic hardware holds great promise for significantly increasing the computation speed and fully leveraging its low energy consumption. In this paper, we develop an end-to-end design framework of photonic SCNN. We present the design of a SCNN tailored for a photonic platform utilizing distributed feedback lasers with a saturable absorber (DFB-SA laser) as the photonic spiking neurons. We also introduce hardware implementations for key computational steps in photonic SCNNs, including the nonlinear activation function, the convolutional layer, the fully connected layer, and the max-pooling layer. Additionally, a hardware-aware training method is proposed. Furthermore, we apply the designed network to classify the MNIST, Fashion-MNIST, and CIFAR-10 datasets, achieving accuracies of 96.52%, 90.48%, and 88.45%, respectively, in simulations on the test sets. And we experimentally validate the nonlinear activation function in the MNIST dataset classification task using the DFB-SA laser, achieving a classification accuracy of 96.06%. This study introduces a novel approach to deploying neural networks on hardware, presenting a portable, modular hardware simulation model and training method. This model is anticipated to be seamlessly integrated into the future hardware–software co-design of large-scale photonic SCNNs. Part of the hardware-aware training code is available at https://github.com/Oo-Fish-oO/Hardware-aware-training
{"title":"Hardware–Software Co-design Computational Framework and Hardware-Aware Training for Photonic Spiking Convolutional Networks with DFB-SA Laser","authors":"Chengyang Yu, Shuiying Xiang, Liyan Zhao, Xinran Niu, Wenzhuo Liu, Yuechun Shi, Licun Yu, Yue Hao","doi":"10.1021/acsphotonics.4c02382","DOIUrl":"https://doi.org/10.1021/acsphotonics.4c02382","url":null,"abstract":"Neuromorphic computing stands out as a highly competitive computing paradigm capable of overcoming the bottlenecks inherent in von Neumann architectures. The spiking convolutional neural network (SCNN) is a prominent type of model within the realm of neuromorphic computing. Adapting SCNNs to photonic neuromorphic hardware holds great promise for significantly increasing the computation speed and fully leveraging its low energy consumption. In this paper, we develop an end-to-end design framework of photonic SCNN. We present the design of a SCNN tailored for a photonic platform utilizing distributed feedback lasers with a saturable absorber (DFB-SA laser) as the photonic spiking neurons. We also introduce hardware implementations for key computational steps in photonic SCNNs, including the nonlinear activation function, the convolutional layer, the fully connected layer, and the max-pooling layer. Additionally, a hardware-aware training method is proposed. Furthermore, we apply the designed network to classify the MNIST, Fashion-MNIST, and CIFAR-10 datasets, achieving accuracies of 96.52%, 90.48%, and 88.45%, respectively, in simulations on the test sets. And we experimentally validate the nonlinear activation function in the MNIST dataset classification task using the DFB-SA laser, achieving a classification accuracy of 96.06%. This study introduces a novel approach to deploying neural networks on hardware, presenting a portable, modular hardware simulation model and training method. This model is anticipated to be seamlessly integrated into the future hardware–software co-design of large-scale photonic SCNNs. Part of the hardware-aware training code is available at https://github.com/Oo-Fish-oO/Hardware-aware-training","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"48 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144370982","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 : 2025-06-23DOI: 10.1021/acsphotonics.5c00405
Siqi Li, Lan Yu, Min Liu, Wenfu Zhang, Peng Gao, Guoxi Wang
Measuring the dynamics of flowing particles is crucial for various fields, including biophysics, industrial inspection, and environmental monitoring. Here, we present a multifocal metalens for correlation spectroscopy, enabling measuring microfluidic dynamics in a wide measuring range without the need of fluorescence labeling. The metalens here allows implementation of correlation spectroscopy without relying on bulk optical components, such as differential interference contrast prism and Mach–Zehnder (M–Z) interferometers, thereby significantly reducing experimental complexity and enhancing measurement reliability. Employing the appropriate fitting model, we accurately predict the concentration and flow velocity of poly(methyl methacrylate) microspheres and rat’s blood within microfluidic channels. The proposed multifocal metalens-assisted correlation spectroscopy approach provides new avenues for dynamics measurement in microfluidic devices and can be applied in biomedical diagnostics, environmental monitoring, and lab-on-a-chip systems.
{"title":"Multifocal Metalens-Assisted Correlation Spectroscopy for Measuring Microfluidic Dynamics","authors":"Siqi Li, Lan Yu, Min Liu, Wenfu Zhang, Peng Gao, Guoxi Wang","doi":"10.1021/acsphotonics.5c00405","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c00405","url":null,"abstract":"Measuring the dynamics of flowing particles is crucial for various fields, including biophysics, industrial inspection, and environmental monitoring. Here, we present a multifocal metalens for correlation spectroscopy, enabling measuring microfluidic dynamics in a wide measuring range without the need of fluorescence labeling. The metalens here allows implementation of correlation spectroscopy without relying on bulk optical components, such as differential interference contrast prism and Mach–Zehnder (M–Z) interferometers, thereby significantly reducing experimental complexity and enhancing measurement reliability. Employing the appropriate fitting model, we accurately predict the concentration and flow velocity of poly(methyl methacrylate) microspheres and rat’s blood within microfluidic channels. The proposed multifocal metalens-assisted correlation spectroscopy approach provides new avenues for dynamics measurement in microfluidic devices and can be applied in biomedical diagnostics, environmental monitoring, and lab-on-a-chip systems.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"25 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144370983","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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