Large-aperture optical components are of paramount importance in domains such as integrated circuits,photolithography,aerospace,and inertial confinement fusion.However,measuring their surface profiles relies predomina...Large-aperture optical components are of paramount importance in domains such as integrated circuits,photolithography,aerospace,and inertial confinement fusion.However,measuring their surface profiles relies predominantly on the phase-shifting approach,which involves collecting multiple interferograms and imposes stringent demands on environmental stability.These issues significantly hinder its ability to achieve real-time and dynamic high-precision measurements.Therefore,this study proposes a high-precision large-aperture single-frame interferometric surface profile measurement(LA-SFISPM)method based on deep learning and explores its capability to realize dynamic measurements with high accuracy.The interferogram is matched to the phase by training the data measured using the small aperture.The consistency of the surface features of the small and large apertures is enhanced via contrast learning and feature-distribution alignment.Hence,high-precision phase reconstruction of large-aperture optical components can be achieved without using a phase shifter.The experimental results show that for the tested mirror withΦ=820 mm,the surface profile obtained from LA-SFISPM is subtracted point-by-point from the ground truth,resulting in a maximum single-point error of 4.56 nm.Meanwhile,the peak-to-valley(PV)value is 0.0758λ,and the simple repeatability of root mean square(SR-RMS)value is 0.00025λ,which aligns well with the measured results obtained by ZYGO.In particular,a significant reduction in the measurement time(reduced by a factor of 48)is achieved compared with that of the traditional phase-shifting method.Our proposed method provides an efficient,rapid,and accurate method for obtaining the surface profiles of optical components with different diameters without employing a phase-shifting approach,which is highly desired in large-aperture interferometric measurement systems.展开更多
This study aims to improve the integrated testing of large-aperture telescopes to clarify the fundamental principles of an integrated testing system based on astrophotonics.Our demonstration and analyses focused on el...This study aims to improve the integrated testing of large-aperture telescopes to clarify the fundamental principles of an integrated testing system based on astrophotonics.Our demonstration and analyses focused on element-position sensing and modulation based on spatial near-geometric beams,high-throughput step-difference measurements based on channel spectroscopy,distributed broadband-transmittance testing,and standard spectral tests based on near-field energy regulation.Comprehensive analyses and experiments were conducted to confirm the feasibility of the proposed system in the integrated testing process of large-aperture telescopes.The results demonstrated that the angular resolution of the light rays exceeded 5arcsec,which satisfies the requirements for component-position detection in future large-aperture telescopes.The measurement resolution of the wavefront tilt was better than 0.45μrad.Based on the channel spectral method—which combined a high signal-to-noise ratio and high sensitivity,along with continuous-spectral digital segmentation and narrowband-spectral physical segmentation—a resolution of 0.050μm and a range of 50μm were obtained.After calibration,the measurement resolution of the pupil deviation improved to exceed 4%accuracy,and the transmission measurements achieved a consistency of over 2%accuracy.Regarding fringe-broadband interferometry measurements,the system maintained high stability,ensuring its operation within the coherence length,and robustly detected the energy without unwrapping the phase.The use of a projector for calibrating broadband-spectrum measurements led to a reduction in contrast from 0.8142 to 0.6038,which further validates the system's applicability in the integrated testing process of large-aperture telescopes.This study greatly enhanced the observational capabilities of large-aperture telescopes while reducing the integrated system's volume,weight,and power consumption.展开更多
Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional d...Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional design methods neglect the coupling effect between adjacent meta-atoms,thus harming the practical performance of meta-devices.The existing physical/data-driven optimization algorithms can solve the above problems,but bring significant time costs or require a large number of data-sets.Here,we propose a physics-data-driven method employing an“intelligent optimizer”that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones.The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling,and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^(−3).Based on the“intelligent optimizer”,a 1-cm-diameter metalens is designed within 3 hours,and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4%(compared to the ideal focusing efficiency)and a Strehl ratio of 0.94.Compared to previous inverse design method,our method significantly boosts designing efficiency with five orders of magnitude reduction in time.More generally,it may set a new paradigm for devising large-aperture meta-devices.展开更多
Deuterated potassium dihydrogen phosphate damage performance at 351 nm is studied on a large-aperture laser system. Bulk and rear-surface damage are initiated under the 3ω fluences of 6.T J/cm2 and 33/cm2, and show d...Deuterated potassium dihydrogen phosphate damage performance at 351 nm is studied on a large-aperture laser system. Bulk and rear-surface damage are initiated under the 3ω fluences of 6.T J/cm2 and 33/cm2, and show different growth characteristics under multiple laser irradiations with the fluence of 6 J/cm2. The size and number of bulk damage keep unchanged once initiated. However, surface damage size also does not grow, while surface damage number increases linearly with laser shots. Different damage thresholds and growth behaviors suggest different formations of bulk and surface damage precursors. The cause of surface damage is supposed to be near-surface absorbing particles buried under the sol-gel coating.展开更多
Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility.Chemical reactions play a significant ...Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility.Chemical reactions play a significant role in plasma cleaning,which is a complex process involving abundant bond cleavage and species generation.In this work,experiments and reactive molecular dynamics simulations were carried out to unravel the reaction mechanism between the benchmark organic contaminants of dibutyl phthalate and air plasma.The optical emission spectroscopy was used to study the overall evolution behaviors of excited molecular species and radical signals from air plasma as a reference to simulations.Detailed reaction pathways were revealed and characterized,and specific intermediate radicals and products were analyzed during experiments and simulation.The reactive species in the air plasma,such as O,HO_(2)and O_(3)radicals,played a crucial role in cleaving organic molecular structures.Together,our findings provide an atomic-level understanding of complex reaction processes of low-pressure air plasma cleaning mechanisms and are essential for its application in industrial plasma cleaning.展开更多
Achieving complex pulses with high-power lasers necessitates rigorous testing of specially designed optical components.The qualification of these components using complementary devices to access both the high-resoluti...Achieving complex pulses with high-power lasers necessitates rigorous testing of specially designed optical components.The qualification of these components using complementary devices to access both the high-resolution and the largeaperture properties, followed by validation using propagation simulations, is proposed here. In particular, the topology of a large-aperture staircase-like Fresnel phase plate used to generate vortex pulses is qualified using a non-contact optical profiler and a large-aperture wavefront measurement setup based on a Shack–Hartmann sensor. The resulting topography is further used for simulating the focus of laser beams after passing through the phase plate. Step height distribution effects on the doughnut-shaped focus are identified, and avoiding the indicated pitfall in the design of the phase plate provides at least a 10-fold reduction of the irradiance modulation on the circumference of the focus in the super-Gaussian case.展开更多
Large-aperture potassium dihydrogen phos- phate （KDP） crystals are widely used in the laser path of inertial confinement fusion （ICF） systems. The most common method of manufacturing half-meter KDP crystals is ult...Large-aperture potassium dihydrogen phos- phate （KDP） crystals are widely used in the laser path of inertial confinement fusion （ICF） systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machin- ing errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.展开更多
To reduce the cost and achieve high diffraction efficiency, a modified moir@ technique for fabricating a large- aperture multi-level Fresnel membrane optic by a novel design of alignment marks is proposed. The modifie...To reduce the cost and achieve high diffraction efficiency, a modified moir@ technique for fabricating a large- aperture multi-level Fresnel membrane optic by a novel design of alignment marks is proposed. The modified moire fringes vary more sensitively with the actual misalignment. Hence, the alignment accuracy is significantly improved. Using the proposed method, a 20 μm thick, four-level Fresnel diffractive polyimide membrane optic with a 200 mm diameter is made, which exhibits over 62% diffraction efficiency into the ＋1 order, and an efficiency root mean square of 0.051.展开更多
Transverse stimulated Raman scattering(TSRS)in potassium dihydrogen phosphate(KDP)and deuterated potassium dihydrogen phosphate(DKDP)plates for large-aperture,inertial confinement fusion(ICF)-class laser systems is a ...Transverse stimulated Raman scattering(TSRS)in potassium dihydrogen phosphate(KDP)and deuterated potassium dihydrogen phosphate(DKDP)plates for large-aperture,inertial confinement fusion(ICF)-class laser systems is a well-recognized limitation giving rise to parasitic energy conversion and laser-induced damage.The onset of TSRS is manifested in plates exposed to the ultraviolet section of the beam.TSRS amplification is a coherent process that grows exponentially and is distributed nonuniformly in the crystal and at the crystal surfaces.To understand the growth and spatial distribution of TSRS energy in various configurations,a modeling approach has been developed to simulate the operational conditions relevant to ICF-class laser systems.Specific aspects explored in this work include(i)the behavior of TSRS in large-aperture crystal plates suitable for third-harmonic generation and use as wave plates for polarization control in current-generation ICF-class laser system configurations;(ii)methods,and their limitations,of TSRS suppression and(iii)optimal geometries to guide future designs.展开更多
Due to laser-induced damage, the aperture of optics is one of the main factors limiting the output capability of highpower laser facilities. Because of the general difficulty in achieving large-aperture optics, an alt...Due to laser-induced damage, the aperture of optics is one of the main factors limiting the output capability of highpower laser facilities. Because of the general difficulty in achieving large-aperture optics, an alternative solution is to tile some small-aperture ones together. We propose an accurate, stable, and automatic method of array element tiling and verify it on a double-pass 1 × 2 tiled-grating compressor in the XG-III laser facility. The test results show the accuracy and stability of the method. This research provides an efficient way to obtain large-aperture optics for high-power laser facilities.展开更多
Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current l...Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.展开更多
Large-aperture gratings have significant applications in inertial confinement fusion, immersion lithography manufacturing and astronomical observation. Currently, it is challenging and expensive to manufacture sizable...Large-aperture gratings have significant applications in inertial confinement fusion, immersion lithography manufacturing and astronomical observation. Currently, it is challenging and expensive to manufacture sizable monolithic gratings.Therefore, tiled multiple small-aperture gratings are preferred. In this study, the impact of seam phase discontinuity on the modulation of the laser beam field was explored based on the measurement results of the Shenguang-II laser large-aperture multi-exposure-tiled grating. An innovative method for accurately calculating the phase jump of multiexposure-tiled grating seams was proposed. An intensive electromagnetic field analysis was performed by applying rigorous coupled-wave analysis to a reasonably constructed micrometer-level periodic grating seam structure, and the phase jump appearing in millimeter-scale seams of large-aperture tiled gratings was obtained accurately.展开更多
Interferometry with computer-generated holograms(CGHs)is a unique solution for the highly accurate testing of large-aperture aspheric mirrors.However,no direct testing method for quantifying the measurement accuracy o...Interferometry with computer-generated holograms(CGHs)is a unique solution for the highly accurate testing of large-aperture aspheric mirrors.However,no direct testing method for quantifying the measurement accuracy of CGHs has been developed.In this study,we developed a methodology for verifying CGH accuracy based on an element that is functionally equivalent to a large-aperture mirror in terms of accuracy verification.The equivalent element decreased the aperture by one or higher orders of magnitude,implying that the mirror could be replaced by a non-CGH technology in a comparison test.In this study,a 281 mm diamond-turned mirror was fabricated as the equivalent element of a 3.5 m aspheric mirror and measured using CGH and LUPHOScan profilometers.Surface error composition and root-mean-square(RMS)density analyses were performed.The methodology verification accuracy of the CGH was 4 nm(RMS)in the low-to mid-frequency bands,with a measured surface accuracy of approximately 10 nm(RMS).This methodology provides a feasible solution for CGH accuracy verification,ensuring high-accuracy and reliable testing of large-aperture aspheric mirrors.展开更多
In this paper,we review the past and recent works on generating intense terahertz(THz)pulses from photoconductive antennas(PCAs).We will focus on two types of large-aperture photoconductive antenna(LAPCA)that can gene...In this paper,we review the past and recent works on generating intense terahertz(THz)pulses from photoconductive antennas(PCAs).We will focus on two types of large-aperture photoconductive antenna(LAPCA)that can generate high-intensity THz pulses(a)those with large-aperture dipoles and(b)those with interdigitated electrodes.We will first describe the principles of THz generation from PCAs.The critical parameters for improving the peak intensity of THz radiation from LAPCAs are summarized.We will then describe the saturation and limitation process of LAPCAs along with the advantages and disadvantages of working with widebandgap semiconductor substrates.Then,we will explain the evolution of LAPCA with interdigitated electrodes,which allows one to reduce the photoconductive gap size,and thus obtain higher bias fields while applying lower voltages.We will also describe recent achievements in intense THz pulses generated by interdigitated LAPCAs based on wide-bandgap semiconductors driven by ampli-fied lasers.Finally,we will discuss the future perspectives of THz pulse generation using LAPCAs.展开更多
基金funded by the National Natural Science Foundation of China Instrumentation Program(52327806)Youth Fund of the National Nature Foundation of China(62405020)China Postdoctoral Science Foundation(2024M764131).
文摘Large-aperture optical components are of paramount importance in domains such as integrated circuits,photolithography,aerospace,and inertial confinement fusion.However,measuring their surface profiles relies predominantly on the phase-shifting approach,which involves collecting multiple interferograms and imposes stringent demands on environmental stability.These issues significantly hinder its ability to achieve real-time and dynamic high-precision measurements.Therefore,this study proposes a high-precision large-aperture single-frame interferometric surface profile measurement(LA-SFISPM)method based on deep learning and explores its capability to realize dynamic measurements with high accuracy.The interferogram is matched to the phase by training the data measured using the small aperture.The consistency of the surface features of the small and large apertures is enhanced via contrast learning and feature-distribution alignment.Hence,high-precision phase reconstruction of large-aperture optical components can be achieved without using a phase shifter.The experimental results show that for the tested mirror withΦ=820 mm,the surface profile obtained from LA-SFISPM is subtracted point-by-point from the ground truth,resulting in a maximum single-point error of 4.56 nm.Meanwhile,the peak-to-valley(PV)value is 0.0758λ,and the simple repeatability of root mean square(SR-RMS)value is 0.00025λ,which aligns well with the measured results obtained by ZYGO.In particular,a significant reduction in the measurement time(reduced by a factor of 48)is achieved compared with that of the traditional phase-shifting method.Our proposed method provides an efficient,rapid,and accurate method for obtaining the surface profiles of optical components with different diameters without employing a phase-shifting approach,which is highly desired in large-aperture interferometric measurement systems.
基金supported by the National Natural Science Foundation of China(Grant No.12133009)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020221)the Science and Technology Development Plan of Jilin Province(Grant No.20220402032GH)。
文摘This study aims to improve the integrated testing of large-aperture telescopes to clarify the fundamental principles of an integrated testing system based on astrophotonics.Our demonstration and analyses focused on element-position sensing and modulation based on spatial near-geometric beams,high-throughput step-difference measurements based on channel spectroscopy,distributed broadband-transmittance testing,and standard spectral tests based on near-field energy regulation.Comprehensive analyses and experiments were conducted to confirm the feasibility of the proposed system in the integrated testing process of large-aperture telescopes.The results demonstrated that the angular resolution of the light rays exceeded 5arcsec,which satisfies the requirements for component-position detection in future large-aperture telescopes.The measurement resolution of the wavefront tilt was better than 0.45μrad.Based on the channel spectral method—which combined a high signal-to-noise ratio and high sensitivity,along with continuous-spectral digital segmentation and narrowband-spectral physical segmentation—a resolution of 0.050μm and a range of 50μm were obtained.After calibration,the measurement resolution of the pupil deviation improved to exceed 4%accuracy,and the transmission measurements achieved a consistency of over 2%accuracy.Regarding fringe-broadband interferometry measurements,the system maintained high stability,ensuring its operation within the coherence length,and robustly detected the energy without unwrapping the phase.The use of a projector for calibrating broadband-spectrum measurements led to a reduction in contrast from 0.8142 to 0.6038,which further validates the system's applicability in the integrated testing process of large-aperture telescopes.This study greatly enhanced the observational capabilities of large-aperture telescopes while reducing the integrated system's volume,weight,and power consumption.
基金supported by the National Key Research and Development Program (2021YFA1401000)the National Natural Science Foundation of China (No.61975210,62175242 and 62305345)Sichuan Science and Technology Program (2020YFJ0001).
文摘Metalenses have gained significant attention and have been widely utilized in optical systems for focusing and imaging,owing to their lightweight,high-integration,and exceptional-flexibility capabilities.Traditional design methods neglect the coupling effect between adjacent meta-atoms,thus harming the practical performance of meta-devices.The existing physical/data-driven optimization algorithms can solve the above problems,but bring significant time costs or require a large number of data-sets.Here,we propose a physics-data-driven method employing an“intelligent optimizer”that enables us to adaptively modify the sizes of the meta-atom according to the sizes of its surrounding ones.The implementation of such a scheme effectively mitigates the undesired impact of local lattice coupling,and the proposed network model works well on thousands of data-sets with a validation loss of 3×10^(−3).Based on the“intelligent optimizer”,a 1-cm-diameter metalens is designed within 3 hours,and the experimental results show that the 1-mm-diameter metalens has a relative focusing efficiency of 93.4%(compared to the ideal focusing efficiency)and a Strehl ratio of 0.94.Compared to previous inverse design method,our method significantly boosts designing efficiency with five orders of magnitude reduction in time.More generally,it may set a new paradigm for devising large-aperture meta-devices.
基金Supported by the National Natural Science Foundation of China under Grant No 61505187
文摘Deuterated potassium dihydrogen phosphate damage performance at 351 nm is studied on a large-aperture laser system. Bulk and rear-surface damage are initiated under the 3ω fluences of 6.T J/cm2 and 33/cm2, and show different growth characteristics under multiple laser irradiations with the fluence of 6 J/cm2. The size and number of bulk damage keep unchanged once initiated. However, surface damage size also does not grow, while surface damage number increases linearly with laser shots. Different damage thresholds and growth behaviors suggest different formations of bulk and surface damage precursors. The cause of surface damage is supposed to be near-surface absorbing particles buried under the sol-gel coating.
基金the Joint Funds of National Natural Science Foundation of China and China Academy of Engineering Physics(NSAF)(No.U2030109)National Natural Science Foundation of China(No.52075129)。
文摘Low-pressure air plasma cleaning is an effective method for removing organic contaminants on large-aperture optical components in situ in the inertial confinement fusion facility.Chemical reactions play a significant role in plasma cleaning,which is a complex process involving abundant bond cleavage and species generation.In this work,experiments and reactive molecular dynamics simulations were carried out to unravel the reaction mechanism between the benchmark organic contaminants of dibutyl phthalate and air plasma.The optical emission spectroscopy was used to study the overall evolution behaviors of excited molecular species and radical signals from air plasma as a reference to simulations.Detailed reaction pathways were revealed and characterized,and specific intermediate radicals and products were analyzed during experiments and simulation.The reactive species in the air plasma,such as O,HO_(2)and O_(3)radicals,played a crucial role in cleaving organic molecular structures.Together,our findings provide an atomic-level understanding of complex reaction processes of low-pressure air plasma cleaning mechanisms and are essential for its application in industrial plasma cleaning.
基金realized through the‘Nucleu’program,funded by the Romanian Ministry for Education and Research,project number PN 23210105 Faza 3(II)supported through IOSIN‘Sistem Laser De Mare Putere(HPLS)Si Laborator Optic a IFIN-HH/ELI-NP’,through CNCS-UEFISCDI(PN-IIIP4-ID-PCCF-2016–0164),through EU-H2020871161(IMPULSE)and by ELI-NP Phase II+1 种基金the Romanian Government and the European Union through the European Regional Development Fund and the Competitiveness Operational Programme(1/07.07.2016,COP,ID 1334)ELI-RO/DFG/2023˙001 ARNPhot funded by the Institute of Atomic Physics Romania
文摘Achieving complex pulses with high-power lasers necessitates rigorous testing of specially designed optical components.The qualification of these components using complementary devices to access both the high-resolution and the largeaperture properties, followed by validation using propagation simulations, is proposed here. In particular, the topology of a large-aperture staircase-like Fresnel phase plate used to generate vortex pulses is qualified using a non-contact optical profiler and a large-aperture wavefront measurement setup based on a Shack–Hartmann sensor. The resulting topography is further used for simulating the focus of laser beams after passing through the phase plate. Step height distribution effects on the doughnut-shaped focus are identified, and avoiding the indicated pitfall in the design of the phase plate provides at least a 10-fold reduction of the irradiance modulation on the circumference of the focus in the super-Gaussian case.
文摘Large-aperture potassium dihydrogen phos- phate （KDP） crystals are widely used in the laser path of inertial confinement fusion （ICF） systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machin- ing errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.
基金supported by the National Natural Science Foundation of China under Grant No.11375175
文摘To reduce the cost and achieve high diffraction efficiency, a modified moir@ technique for fabricating a large- aperture multi-level Fresnel membrane optic by a novel design of alignment marks is proposed. The modified moire fringes vary more sensitively with the actual misalignment. Hence, the alignment accuracy is significantly improved. Using the proposed method, a 20 μm thick, four-level Fresnel diffractive polyimide membrane optic with a 200 mm diameter is made, which exhibits over 62% diffraction efficiency into the ＋1 order, and an efficiency root mean square of 0.051.
基金This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856,the University of Rochester and the New York State Energy Research and Development Authority。
文摘Transverse stimulated Raman scattering(TSRS)in potassium dihydrogen phosphate(KDP)and deuterated potassium dihydrogen phosphate(DKDP)plates for large-aperture,inertial confinement fusion(ICF)-class laser systems is a well-recognized limitation giving rise to parasitic energy conversion and laser-induced damage.The onset of TSRS is manifested in plates exposed to the ultraviolet section of the beam.TSRS amplification is a coherent process that grows exponentially and is distributed nonuniformly in the crystal and at the crystal surfaces.To understand the growth and spatial distribution of TSRS energy in various configurations,a modeling approach has been developed to simulate the operational conditions relevant to ICF-class laser systems.Specific aspects explored in this work include(i)the behavior of TSRS in large-aperture crystal plates suitable for third-harmonic generation and use as wave plates for polarization control in current-generation ICF-class laser system configurations;(ii)methods,and their limitations,of TSRS suppression and(iii)optimal geometries to guide future designs.
基金Project supported by the National Natural Science Foundation of China(Grant No.61308040)the National High Technology Research and Development Program of China(Grant No.2013AA8043047)
文摘Due to laser-induced damage, the aperture of optics is one of the main factors limiting the output capability of highpower laser facilities. Because of the general difficulty in achieving large-aperture optics, an alternative solution is to tile some small-aperture ones together. We propose an accurate, stable, and automatic method of array element tiling and verify it on a double-pass 1 × 2 tiled-grating compressor in the XG-III laser facility. The test results show the accuracy and stability of the method. This research provides an efficient way to obtain large-aperture optics for high-power laser facilities.
基金supported by the National Key Research and Development Program of China (2022YFB4602600)National Natural Science Foundation of China (Grant Nos. 52425508 & 52221001)the Hunan Provincial Natural Science Foundation of China (2025JJ60286)。
文摘Lithography is a Key enabling technique in modern micro/nano scale technology.Achieving the optimal trade-off between resolution,throughput,and cost remains a central focus in the ongoing development.However,current lithographic techniques such as direct-write,projection,and extreme ultraviolet lithography achieve higher resolution at the expense of increased complexity in optical systems or the use of shorter-wavelength light sources,thus raising the overall cost of production.Here,we present a cost-effective and wafer-level perfect conformal contact lithography at the diffraction limit.By leveraging a transferable photoresist,the technique ensures optimal contact between the mask and photoresist with zero-gap,facilitating the transfer of patterns at the diffraction limit while maintaining high fidelity and uniformity across large wafers.This technique applies to a wide range of complex surfaces,including non-conductive glass surfaces,flexible substrates,and curved surfaces.The proposed technique expands the potential of contact photolithography for novel device architectures and practic al manufacturing processes.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA25020104)
文摘Large-aperture gratings have significant applications in inertial confinement fusion, immersion lithography manufacturing and astronomical observation. Currently, it is challenging and expensive to manufacture sizable monolithic gratings.Therefore, tiled multiple small-aperture gratings are preferred. In this study, the impact of seam phase discontinuity on the modulation of the laser beam field was explored based on the measurement results of the Shenguang-II laser large-aperture multi-exposure-tiled grating. An innovative method for accurately calculating the phase jump of multiexposure-tiled grating seams was proposed. An intensive electromagnetic field analysis was performed by applying rigorous coupled-wave analysis to a reasonably constructed micrometer-level periodic grating seam structure, and the phase jump appearing in millimeter-scale seams of large-aperture tiled gratings was obtained accurately.
基金supported by the National Natural Science Foundation of China(62127901,52375471,and 62305333)supported by the National Key Research and Development Program(2022YFB3403405)+2 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences(2019221)Young Elite Scientists Sponsorship Program of CAST(2022QNRC001)Young Elite Scientists Sponsorship Program of Jilin Province(QT202222).
文摘Interferometry with computer-generated holograms(CGHs)is a unique solution for the highly accurate testing of large-aperture aspheric mirrors.However,no direct testing method for quantifying the measurement accuracy of CGHs has been developed.In this study,we developed a methodology for verifying CGH accuracy based on an element that is functionally equivalent to a large-aperture mirror in terms of accuracy verification.The equivalent element decreased the aperture by one or higher orders of magnitude,implying that the mirror could be replaced by a non-CGH technology in a comparison test.In this study,a 281 mm diamond-turned mirror was fabricated as the equivalent element of a 3.5 m aspheric mirror and measured using CGH and LUPHOScan profilometers.Surface error composition and root-mean-square(RMS)density analyses were performed.The methodology verification accuracy of the CGH was 4 nm(RMS)in the low-to mid-frequency bands,with a measured surface accuracy of approximately 10 nm(RMS).This methodology provides a feasible solution for CGH accuracy verification,ensuring high-accuracy and reliable testing of large-aperture aspheric mirrors.
文摘In this paper,we review the past and recent works on generating intense terahertz(THz)pulses from photoconductive antennas(PCAs).We will focus on two types of large-aperture photoconductive antenna(LAPCA)that can generate high-intensity THz pulses(a)those with large-aperture dipoles and(b)those with interdigitated electrodes.We will first describe the principles of THz generation from PCAs.The critical parameters for improving the peak intensity of THz radiation from LAPCAs are summarized.We will then describe the saturation and limitation process of LAPCAs along with the advantages and disadvantages of working with widebandgap semiconductor substrates.Then,we will explain the evolution of LAPCA with interdigitated electrodes,which allows one to reduce the photoconductive gap size,and thus obtain higher bias fields while applying lower voltages.We will also describe recent achievements in intense THz pulses generated by interdigitated LAPCAs based on wide-bandgap semiconductors driven by ampli-fied lasers.Finally,we will discuss the future perspectives of THz pulse generation using LAPCAs.
