Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHE...Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHEAs),which are difficult to synthesize and process by conventional methods.To evaluate a possible way to accelerate the process,high-throughput laser metal deposition was used in this work to prepare a quinary RHEA,TiZrNbHfTa,as well as its quaternary and ternary subsystems by in-situ alloying of elemental powders.Compositionally graded variants of the quinary RHEA were also analyzed.Our results show that the influence of various parameters such as powder shape and purity,alloy composition,and especially the solidification range,on the processability,microstructure,porosity,and mechanical properties can be investigated rapidly.The strength of these alloys was mainly affected by the oxygen and nitrogen contents of the starting powders,while substitutional solid solution strengthening played a minor role.展开更多
During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the ...During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the approach is hindered by the restricted applicability of the known configurations for ambient variations quantification outside the laboratory conditions and their low affordability,where necessity on the spectrally-resolved data collection is among the main limiting factors.In this paper we demonstrate the first realization of an affordable whispering gallery mode sensor powered by deep learning and multi-resonator imaging at a fixed frequency.It has been shown that the approach enables refractive index unit(RIU)prediction with an absolute error at 3×10^(-6) level for dynamic range of the RIU variations from 0 to 2×10^(-3) with temporal resolution of several milliseconds and instrument-driven detection limit of 3×10−5.High sensing accuracy together with instrumental affordability and production simplicity places the reported detector among the most cost-effective realizations of the whispering gallery mode approach.The proposed solution is expected to have a great impact on the shift of the whole sensing paradigm away from the model-based and to the flexible self-learning solutions.展开更多
Accurate wavelength measurement is critical for spectroscopy,optical communications,semiconductor manufacturing,and quantum research.Emerging reconstructive wavemeters are compact,cost-effective devices that utilize p...Accurate wavelength measurement is critical for spectroscopy,optical communications,semiconductor manufacturing,and quantum research.Emerging reconstructive wavemeters are compact,cost-effective devices that utilize pseudo-random wavelength patterns and computational techniques to provide high-resolution,broadband alternatives to solutions based on frequency beating and interferometry.We propose a novel reconstructive wavemeter that synergizes the advantages of both approaches.Its physical model is based on the integration of thousands of high-quality-factor optical microcavities,which are deformed to stimulate whispering gallery mode splitting.For realizing a wavelength interpreter,we developed a hybrid machine learning approach utilizing boosting methods and variational autoencoders.This enabled the implementation of wavelength interpretation as a rigorous regression task for the first time.The introduced novel concept ensures the uniqueness of the wavelength patterns up to ultra-wide(~100 nm)spectral window while guarantees high(~100 fm)intrinsic sensitivity.The latter allocates the proposed solution right next to the ultimate reconstructive wavemeters based on integrating spheres,but with less calibration efforts,featuring superior miniaturization options and chip-scale integrability.展开更多
A high beam quality,all-solid-state Nd:YAG laser system of high-repetition frequency has been built for Thomson scattering diagnosis.A 1.7 times diffraction limited output beam at a pulse energy of 5 J at 1064 nm is a...A high beam quality,all-solid-state Nd:YAG laser system of high-repetition frequency has been built for Thomson scattering diagnosis.A 1.7 times diffraction limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns(FWHM)and a repetition rate of 200 Hz;the output energy stability is 4.9%peak-to-valley over 6000 shots.A novel pulsed laser system(Supplementary Fig.S1)with high average power and high beam quality has recently been built by Dr Zhong-Wei Fan's group at the Academy of Opto-Electronics,Chinese Academy of Sciences.Both the laser diode side-pumped rod and slab crystals are integrated into the amplifier(AMP)system.A 1.7 times diffraction-limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns(FWHM)and a repetition rate of 200 Hz;the output energy stability is 4.9%peak-to-valley over 6000 shots.The test results are shown in Figure 1a and 1b.展开更多
Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn signifcantly afects successive laser-material interactions.By recording the dyn...Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn signifcantly afects successive laser-material interactions.By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy,here we present direct visualization of the excitation of air plasma induced by the refected laser during the second pulse irradiation.Te interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction,showing anisotropic expansion dynamics in diferent directions.We further demonstrate the vanishing of air plasma as the pulse number increases because of the generation of a rough surface without light focusing ability.In the scenario,the interaction of air plasma and silicon plasma disappears;the expansion of the silicon plasma and shockwave restores its original characteristic that is dominated by the laser-material coupling.Te results show that the excitation of air plasma and the laser-material coupling involved in laser-induced plasma and shockwave expansion are structure mediated and dependent on the pulse number,which is of fundamental importance for deep insight into the nature of laser-material interactions during multiple pulses ablation.展开更多
For future micro-and nanotechnologies,the manufacturing of miniaturized,functionalized,and integrated devices is indispensable.In this paper,an assembly technique based on a bottom-up strategy that enables the manufac...For future micro-and nanotechnologies,the manufacturing of miniaturized,functionalized,and integrated devices is indispensable.In this paper,an assembly technique based on a bottom-up strategy that enables the manufacturing of complex microsystems using only optical methods is presented.A screw connection is transferred to the micrometer range and used to assemble screwand nut-shaped microcomponents.Micro-stereolithography is performed by means of two-photon polymerization,and microstructures are fabricated and subsequently trapped,moved,and screwed together using optical forces in a holographic optical tweezer set-up.The design and construction of interlocking microcomponents and the verification of a stable and releasable joint form the main focus of this paper.The assembly technique is also applied to a microfluidic system to enable the pumping or intermixing of fluids on a microfluidic chip.This strategy not only enables the assembly of microcomponents but also the combination of different materials and features to form complex hybrid microsystems.展开更多
The per-and polyfluoroalkyl substances(PFAS)are a group of organofluorine chemicals treated as the emerging pollutants that are currently of particularly acute concern.These compounds have been employed intensively as...The per-and polyfluoroalkyl substances(PFAS)are a group of organofluorine chemicals treated as the emerging pollutants that are currently of particularly acute concern.These compounds have been employed intensively as surfactants over multiple decades and are already to be found in surface and ground waters at amounts sufficient to have an effect on human health and ecosystems.Because of the carbon–fluorine bonds,the PFAS have an extreme environmental persistence and their negative impact accumulates with further production and penetration into the environment.In Germany alone,more than thousands of sites have been identified as contaminated with PFAS;thus,timely detection of PFAS residue is becoming a high priority.In this paper,we report on the high performance optical detection method based on whispering gallery mode(WGM)microcavities applied for the first time to detect PFAS contaminants in aqueous solutions.A self-sensing boosted 4D microcavity fabricated with two-photon polymerization is employed as an individual sensing unit.In an example of the multiplexed imaging sensor with multiple hundreds of simultaneously interrogated microcavities we demonstrate the possibility to detect the PFAS chemicals representatives at a level down to 1 ppb(parts per billion).展开更多
Although optical microscopy is a widely used technique across various multidisciplinary fields for inspecting small-scale objects,surfaces or organisms,it faces a significant limitation:the lateral resolution of optic...Although optical microscopy is a widely used technique across various multidisciplinary fields for inspecting small-scale objects,surfaces or organisms,it faces a significant limitation:the lateral resolution of optical microscopes is fundamentally constrained by light diffraction.Dielectric micro-spheres,however,offer a promising solution to this issue as they are capable of significantly enhancing lateral resolution through extraordinary phenomena,such as a photonic nanojet.Building upon the potential of dielectric micro-spheres,this paper introduces a novel approach for fabricating 3D micro-devices designed to enhance lateral resolution in optical microscopy.The proposed 3D micro-device comprises a modified coverslip and a micro-sphere,facilitating easy handling and integration into any existing optical microscope.To manufacture the device,two advanced femtosecond laser techniques are employed:femtosecond laser ablation and multi-photon lithography.Femtosecond laser ablation was employed to create a micro-hole in the coverslip,which allows light to be focused through this aperture.Multi-photon lithography was used to fabricate a micro-sphere with a diameter of 20μm,along with a cantilever that positions the above the processed micro-hole and connect it with the coverslip.In this context,advanced processing strategies for multi-photon lithography to produce a micro-sphere with superior surface roughness and almost perfect geometry(λ/8)from a Zr-based hybrid photoresist are demonstrated.The performance of the micro-device was evaluated using Mirau-type coherence scanning interferometry in conjunction with white light illumination at a central wavelength of 600 nm and a calibration grid(Λ=0.28μm,h>50 nm).Here,the 3D micro-device proved to be capable of enhancing lateral resolution beyond the limits achievable with conventional lenses or microscope objectives when used in air.Simultaneously,it maintained the high axial resolution characteristic of Mirau-type coherence scanning interferometry.The results and optical properties of the micro-sphere were analyzed and further discussed through simulations.展开更多
Water monitoring,environmental analysis,cell culture stability,and biomedical applications require precise pH control.Traditional methods,such as pH strips and meters,have limitations:pH strips lack precision,whereas ...Water monitoring,environmental analysis,cell culture stability,and biomedical applications require precise pH control.Traditional methods,such as pH strips and meters,have limitations:pH strips lack precision,whereas electrochemical meters,although more accurate,are fragile,prone to drift,and unsuitable for small volumes.In this paper,we propose a method for the optical detection of pH based on a multiplexed sensor with 4D microcavities fabricated via two-photon polymerization.This approach employs pH-triggered reversible variations in microresonator geometry and integrates hundreds of dual optically coupled 4D microcavities to achieve the detection limit of 0.003 pH units.The proposed solution is a clear example of the use-case-oriented application of two-photon polymerized structures of high optical quality.Owing to the benefits of the multiplexed imaging platform,the dual 4D microresonators can be integrated with other microresonator types for pH-corrected biochemical studies.展开更多
基金GL and ELG acknowledge funding from the German Research Foundation in the framework of the priority program SPP 2006—Compositionally Complex Alloys—High Entropy Alloys,projects LA 3607/3-1 and GU 1075/12-1.EPG is supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,Materials Sciences and Engineering Division.
文摘Progress in materials development is often paced by the time required to produce and evaluate a large number of alloys with different chemical compositions.This applies especially to refractory high-entropy alloys(RHEAs),which are difficult to synthesize and process by conventional methods.To evaluate a possible way to accelerate the process,high-throughput laser metal deposition was used in this work to prepare a quinary RHEA,TiZrNbHfTa,as well as its quaternary and ternary subsystems by in-situ alloying of elemental powders.Compositionally graded variants of the quinary RHEA were also analyzed.Our results show that the influence of various parameters such as powder shape and purity,alloy composition,and especially the solidification range,on the processability,microstructure,porosity,and mechanical properties can be investigated rapidly.The strength of these alloys was mainly affected by the oxygen and nitrogen contents of the starting powders,while substitutional solid solution strengthening played a minor role.
文摘During the last decades the whispering gallery mode based sensors have become a prominent solution for label-free sensing of various physical and chemical parameters.At the same time,the widespread utilization of the approach is hindered by the restricted applicability of the known configurations for ambient variations quantification outside the laboratory conditions and their low affordability,where necessity on the spectrally-resolved data collection is among the main limiting factors.In this paper we demonstrate the first realization of an affordable whispering gallery mode sensor powered by deep learning and multi-resonator imaging at a fixed frequency.It has been shown that the approach enables refractive index unit(RIU)prediction with an absolute error at 3×10^(-6) level for dynamic range of the RIU variations from 0 to 2×10^(-3) with temporal resolution of several milliseconds and instrument-driven detection limit of 3×10−5.High sensing accuracy together with instrumental affordability and production simplicity places the reported detector among the most cost-effective realizations of the whispering gallery mode approach.The proposed solution is expected to have a great impact on the shift of the whole sensing paradigm away from the model-based and to the flexible self-learning solutions.
文摘Accurate wavelength measurement is critical for spectroscopy,optical communications,semiconductor manufacturing,and quantum research.Emerging reconstructive wavemeters are compact,cost-effective devices that utilize pseudo-random wavelength patterns and computational techniques to provide high-resolution,broadband alternatives to solutions based on frequency beating and interferometry.We propose a novel reconstructive wavemeter that synergizes the advantages of both approaches.Its physical model is based on the integration of thousands of high-quality-factor optical microcavities,which are deformed to stimulate whispering gallery mode splitting.For realizing a wavelength interpreter,we developed a hybrid machine learning approach utilizing boosting methods and variational autoencoders.This enabled the implementation of wavelength interpretation as a rigorous regression task for the first time.The introduced novel concept ensures the uniqueness of the wavelength patterns up to ultra-wide(~100 nm)spectral window while guarantees high(~100 fm)intrinsic sensitivity.The latter allocates the proposed solution right next to the ultimate reconstructive wavemeters based on integrating spheres,but with less calibration efforts,featuring superior miniaturization options and chip-scale integrability.
文摘A high beam quality,all-solid-state Nd:YAG laser system of high-repetition frequency has been built for Thomson scattering diagnosis.A 1.7 times diffraction limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns(FWHM)and a repetition rate of 200 Hz;the output energy stability is 4.9%peak-to-valley over 6000 shots.A novel pulsed laser system(Supplementary Fig.S1)with high average power and high beam quality has recently been built by Dr Zhong-Wei Fan's group at the Academy of Opto-Electronics,Chinese Academy of Sciences.Both the laser diode side-pumped rod and slab crystals are integrated into the amplifier(AMP)system.A 1.7 times diffraction-limited output beam at a pulse energy of 5 J at 1064 nm is achieved for the first time with a pulse duration of 6.6 ns(FWHM)and a repetition rate of 200 Hz;the output energy stability is 4.9%peak-to-valley over 6000 shots.The test results are shown in Figure 1a and 1b.
基金Tis research was supported by the National Key R&D Program of China(grant no.2017YFB1104300)and the National Natural Science Foundation of China(grant nos.91323301,11704028).
文摘Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn signifcantly afects successive laser-material interactions.By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy,here we present direct visualization of the excitation of air plasma induced by the refected laser during the second pulse irradiation.Te interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction,showing anisotropic expansion dynamics in diferent directions.We further demonstrate the vanishing of air plasma as the pulse number increases because of the generation of a rough surface without light focusing ability.In the scenario,the interaction of air plasma and silicon plasma disappears;the expansion of the silicon plasma and shockwave restores its original characteristic that is dominated by the laser-material coupling.Te results show that the excitation of air plasma and the laser-material coupling involved in laser-induced plasma and shockwave expansion are structure mediated and dependent on the pulse number,which is of fundamental importance for deep insight into the nature of laser-material interactions during multiple pulses ablation.
基金We thank the German Research Foundation DFG(Deutsche Forschungsgesellschaft)for their generous support within the Reinhardt Koselleck project(OS 188/28-1).
文摘For future micro-and nanotechnologies,the manufacturing of miniaturized,functionalized,and integrated devices is indispensable.In this paper,an assembly technique based on a bottom-up strategy that enables the manufacturing of complex microsystems using only optical methods is presented.A screw connection is transferred to the micrometer range and used to assemble screwand nut-shaped microcomponents.Micro-stereolithography is performed by means of two-photon polymerization,and microstructures are fabricated and subsequently trapped,moved,and screwed together using optical forces in a holographic optical tweezer set-up.The design and construction of interlocking microcomponents and the verification of a stable and releasable joint form the main focus of this paper.The assembly technique is also applied to a microfluidic system to enable the pumping or intermixing of fluids on a microfluidic chip.This strategy not only enables the assembly of microcomponents but also the combination of different materials and features to form complex hybrid microsystems.
基金Bundesministerium für Bildung und Forschung(03VP08220)。
文摘The per-and polyfluoroalkyl substances(PFAS)are a group of organofluorine chemicals treated as the emerging pollutants that are currently of particularly acute concern.These compounds have been employed intensively as surfactants over multiple decades and are already to be found in surface and ground waters at amounts sufficient to have an effect on human health and ecosystems.Because of the carbon–fluorine bonds,the PFAS have an extreme environmental persistence and their negative impact accumulates with further production and penetration into the environment.In Germany alone,more than thousands of sites have been identified as contaminated with PFAS;thus,timely detection of PFAS residue is becoming a high priority.In this paper,we report on the high performance optical detection method based on whispering gallery mode(WGM)microcavities applied for the first time to detect PFAS contaminants in aqueous solutions.A self-sensing boosted 4D microcavity fabricated with two-photon polymerization is employed as an individual sensing unit.In an example of the multiplexed imaging sensor with multiple hundreds of simultaneously interrogated microcavities we demonstrate the possibility to detect the PFAS chemicals representatives at a level down to 1 ppb(parts per billion).
基金supported by the Marie Skłodowska-Curie Actions,under grant agreement No.101059253,as part of the European Union’s Horizon Europe research and innovation programmeIt also received support from a Feodor Lynen Postdoctoral Fellowship awarded by the Alexander von Humboldt Foundation.Additional funding was provided by Laserlab-Europe(Proposal IDs:ULF-FORTH_002794 and ULF-FORTH_025264).We further gratefully acknowledge funding by the German Federal Ministry for Economic Affairs and Climate Action under grant 16KN053050.The authors would also like to thank Mrs.Aleka Manousaki for SEM technical support.
文摘Although optical microscopy is a widely used technique across various multidisciplinary fields for inspecting small-scale objects,surfaces or organisms,it faces a significant limitation:the lateral resolution of optical microscopes is fundamentally constrained by light diffraction.Dielectric micro-spheres,however,offer a promising solution to this issue as they are capable of significantly enhancing lateral resolution through extraordinary phenomena,such as a photonic nanojet.Building upon the potential of dielectric micro-spheres,this paper introduces a novel approach for fabricating 3D micro-devices designed to enhance lateral resolution in optical microscopy.The proposed 3D micro-device comprises a modified coverslip and a micro-sphere,facilitating easy handling and integration into any existing optical microscope.To manufacture the device,two advanced femtosecond laser techniques are employed:femtosecond laser ablation and multi-photon lithography.Femtosecond laser ablation was employed to create a micro-hole in the coverslip,which allows light to be focused through this aperture.Multi-photon lithography was used to fabricate a micro-sphere with a diameter of 20μm,along with a cantilever that positions the above the processed micro-hole and connect it with the coverslip.In this context,advanced processing strategies for multi-photon lithography to produce a micro-sphere with superior surface roughness and almost perfect geometry(λ/8)from a Zr-based hybrid photoresist are demonstrated.The performance of the micro-device was evaluated using Mirau-type coherence scanning interferometry in conjunction with white light illumination at a central wavelength of 600 nm and a calibration grid(Λ=0.28μm,h>50 nm).Here,the 3D micro-device proved to be capable of enhancing lateral resolution beyond the limits achievable with conventional lenses or microscope objectives when used in air.Simultaneously,it maintained the high axial resolution characteristic of Mirau-type coherence scanning interferometry.The results and optical properties of the micro-sphere were analyzed and further discussed through simulations.
基金the German Federal Ministry for Research and Education(BMBF)for partially funding this work under the VIP+-Programme in the project IntellOSS,03VP08220.
文摘Water monitoring,environmental analysis,cell culture stability,and biomedical applications require precise pH control.Traditional methods,such as pH strips and meters,have limitations:pH strips lack precision,whereas electrochemical meters,although more accurate,are fragile,prone to drift,and unsuitable for small volumes.In this paper,we propose a method for the optical detection of pH based on a multiplexed sensor with 4D microcavities fabricated via two-photon polymerization.This approach employs pH-triggered reversible variations in microresonator geometry and integrates hundreds of dual optically coupled 4D microcavities to achieve the detection limit of 0.003 pH units.The proposed solution is a clear example of the use-case-oriented application of two-photon polymerized structures of high optical quality.Owing to the benefits of the multiplexed imaging platform,the dual 4D microresonators can be integrated with other microresonator types for pH-corrected biochemical studies.
