Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is f...Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.展开更多
The stochastic paralld gradient descent （SPGD） algorithm is widely used in wavefront sensor-less adaptive optics （WSAO） systems. However, the convergence is relatively slow. Modal-based algorithms usually provide ...The stochastic paralld gradient descent （SPGD） algorithm is widely used in wavefront sensor-less adaptive optics （WSAO） systems. However, the convergence is relatively slow. Modal-based algorithms usually provide much faster convergence than SPGD; however, the limited actuator stroke of the deformable mirror （DM） often prohibits the sensing of higher-order modes or renders a closed-loop correction inapplicable. Based on a comparative analysis of SPGD and the DM-modal-based algorithm, a hybrid approach involving both algorithms is proposed for extended image-based WSAO, and is demonstrated in this experiment. The hybrid approach can achieve similar correction results to pure SPGD, but with a dramatically decreased iteration number.展开更多
We explore an end-to-end wavefront sensing approach based on deep learning,which aims to deal with the high-order turbulence and the discontinuous aberration caused by optical system obstructions commonly encountered ...We explore an end-to-end wavefront sensing approach based on deep learning,which aims to deal with the high-order turbulence and the discontinuous aberration caused by optical system obstructions commonly encountered in real-world ground-based telescope observations.We have considered factors such as the entrance pupil wavefront containing high-order turbulence and discontinuous aberrations due to obstruction by the secondary mirror and spider,realistically simulating the observation conditions of ground-based telescopes.By comparing with the Marechal criterion(0.075λ),we validate the effectiveness of the proposed approach.Experimental results show that the deep learning wavefront sensing approach can correct the distorted wavefront affect by high-order turbulence to close to the diffraction limit.We also analyze the limitations of this approach,using the direct zonal phase output method,where the residual wavefront stems from the fitting error.Furthermore,we have explored the wavefront reconstruction accuracy of different noise intensities and the central obstruction ratios.Within a noise intensity range of 1%–1.9%,the root mean square error(RMSE)of the residual wavefront is less than Marechal criterion.In the range of central obstruction ratios from 0.0 to 0.3 commonly used in ground-based telescopes,the RMSE of the residual wavefront is greater than 0.039λand less than 0.041λ.This research provides an efficient and valid wavefront sensing approach for high-resolution observation with ground-based telescopes.展开更多
An advanced method for rapidly computing holograms of large three-dimensional(3D)objects combines backward ray tracing with adaptive resolution wavefront recording plane(WRP)and adaptive angular spectrum propagation.I...An advanced method for rapidly computing holograms of large three-dimensional(3D)objects combines backward ray tracing with adaptive resolution wavefront recording plane(WRP)and adaptive angular spectrum propagation.In the initial phase,a WRP with adjustable resolution and sampling interval based on the object’s size is defined to capture detailed information from large 3D objects.The second phase employs an adaptive angular spectrum method(ASM)to efficiently compute the propagation from the large-sized WRP to the small-sized computer-generated hologram(CGH).The computation process is accelerated using CUDA and OptiX.Optical experiments confirm that the algorithm can generate high-quality holograms with shadow and occlusion effects at a resolution of 1024×1024 in 29 ms.展开更多
3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be effi...3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.展开更多
On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both ...On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both theoretical interpreting and computer simulation, explains how to measure the wavefront slope difference between two sub apertures through the determination of image displacements on detector plane. It includes a fast and accurate digital algorithm for detecting wavefront disturbance, which is much suitable for realization in such electrical hardwares as digital signal processors.展开更多
固体MOPA(Master oscillator power amplifier)激光器是一种通过将固体激光器的主振荡器与功率放大器组合,放大低功率信号以输出高功率激光的装置,在激光加工、精密测量、医疗治疗和科学研究等领域有着广泛应用。光束质量作为激光器输...固体MOPA(Master oscillator power amplifier)激光器是一种通过将固体激光器的主振荡器与功率放大器组合,放大低功率信号以输出高功率激光的装置,在激光加工、精密测量、医疗治疗和科学研究等领域有着广泛应用。光束质量作为激光器输出性能的关键指标,直接决定了激光器在这些应用中的效果和精度。但由于固体MOPA激光器中热效应的存在,激光输出过程中常伴随着光束质量的持续恶化,导致性能降低,因此优化光束质量便成为激光器性能提升的关键,在激光器的设计与应用中具有重要的研究与实践意义。本文综述了固体MOPA激光器光束质量优化技术的研究进展,重点介绍了热效应抑制技术、负透镜法、相位共轭法、可变形镜法、球差自补偿法、增益导引法和光束整形法等优化方法。通过分析这些技术的原理、实验进展及应用效果,讨论了它们在提高光束质量方面的挑战和创新成果。此外,文章还指出了固体MOPA激光器在高功率、高效率条件下光束质量优化的难点,并展望了未来可能的研究方向和技术突破。展开更多
基金support from the Biotechnology and Biological Council Doctoral Training Programme(BBSRC DTP)the support from the Royal Society and Wolfson Foundation(RSWF\FT\191022).
文摘Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20131101120023)the Excellent Young Scholars Research Fund of the Beijing Institute of Technology(Grant No.2012YG0203)
文摘The stochastic paralld gradient descent （SPGD） algorithm is widely used in wavefront sensor-less adaptive optics （WSAO） systems. However, the convergence is relatively slow. Modal-based algorithms usually provide much faster convergence than SPGD; however, the limited actuator stroke of the deformable mirror （DM） often prohibits the sensing of higher-order modes or renders a closed-loop correction inapplicable. Based on a comparative analysis of SPGD and the DM-modal-based algorithm, a hybrid approach involving both algorithms is proposed for extended image-based WSAO, and is demonstrated in this experiment. The hybrid approach can achieve similar correction results to pure SPGD, but with a dramatically decreased iteration number.
基金supported by the National Natural Science Foundation of China(NSFC)(U2031140).
文摘We explore an end-to-end wavefront sensing approach based on deep learning,which aims to deal with the high-order turbulence and the discontinuous aberration caused by optical system obstructions commonly encountered in real-world ground-based telescope observations.We have considered factors such as the entrance pupil wavefront containing high-order turbulence and discontinuous aberrations due to obstruction by the secondary mirror and spider,realistically simulating the observation conditions of ground-based telescopes.By comparing with the Marechal criterion(0.075λ),we validate the effectiveness of the proposed approach.Experimental results show that the deep learning wavefront sensing approach can correct the distorted wavefront affect by high-order turbulence to close to the diffraction limit.We also analyze the limitations of this approach,using the direct zonal phase output method,where the residual wavefront stems from the fitting error.Furthermore,we have explored the wavefront reconstruction accuracy of different noise intensities and the central obstruction ratios.Within a noise intensity range of 1%–1.9%,the root mean square error(RMSE)of the residual wavefront is less than Marechal criterion.In the range of central obstruction ratios from 0.0 to 0.3 commonly used in ground-based telescopes,the RMSE of the residual wavefront is greater than 0.039λand less than 0.041λ.This research provides an efficient and valid wavefront sensing approach for high-resolution observation with ground-based telescopes.
基金Project supported by the Special Project of Central Government Guiding Local Science and Technology Development in Beijing 2020(Grant No.Z201100004320006).
文摘An advanced method for rapidly computing holograms of large three-dimensional(3D)objects combines backward ray tracing with adaptive resolution wavefront recording plane(WRP)and adaptive angular spectrum propagation.In the initial phase,a WRP with adjustable resolution and sampling interval based on the object’s size is defined to capture detailed information from large 3D objects.The second phase employs an adaptive angular spectrum method(ASM)to efficiently compute the propagation from the large-sized WRP to the small-sized computer-generated hologram(CGH).The computation process is accelerated using CUDA and OptiX.Optical experiments confirm that the algorithm can generate high-quality holograms with shadow and occlusion effects at a resolution of 1024×1024 in 29 ms.
基金supported by NSFC(Nos.41274120,41404085,and 41504084)
文摘3D traveltime calculation is widely used in seismic exploration technologies such as seismic migration and tomography. The fast marching method （FMM） is useful for calculating 3D traveltime and has proven to be efficient and stable. However, it has low calculation accuracy near the source, which thus gives it low overall accuracy. This paper proposes a joint traveltime calculation method to solve this problem. The method firstly employs the wavefront construction method （WFC）, which has a higher calculation accuracy than FMM in calculating traveltime in the small area near the source, and secondly adopts FMM to calculate traveltime for the remaining grid nodes. Due to the increase in calculation precision of grid nodes near the source, this new algorithm is shown to have good calculation precision while maintaining the high calculation efficiency of FMM, which is employed in most of the computational area. Results are verified using various numerical models.
文摘On the basis of Hartmann Shack sensor imaging analysis, a new method is presented with which the wavefront slope can be obtained when the object is incoherent and extended. This method, which is demonstrated by both theoretical interpreting and computer simulation, explains how to measure the wavefront slope difference between two sub apertures through the determination of image displacements on detector plane. It includes a fast and accurate digital algorithm for detecting wavefront disturbance, which is much suitable for realization in such electrical hardwares as digital signal processors.
文摘固体MOPA(Master oscillator power amplifier)激光器是一种通过将固体激光器的主振荡器与功率放大器组合,放大低功率信号以输出高功率激光的装置,在激光加工、精密测量、医疗治疗和科学研究等领域有着广泛应用。光束质量作为激光器输出性能的关键指标,直接决定了激光器在这些应用中的效果和精度。但由于固体MOPA激光器中热效应的存在,激光输出过程中常伴随着光束质量的持续恶化,导致性能降低,因此优化光束质量便成为激光器性能提升的关键,在激光器的设计与应用中具有重要的研究与实践意义。本文综述了固体MOPA激光器光束质量优化技术的研究进展,重点介绍了热效应抑制技术、负透镜法、相位共轭法、可变形镜法、球差自补偿法、增益导引法和光束整形法等优化方法。通过分析这些技术的原理、实验进展及应用效果,讨论了它们在提高光束质量方面的挑战和创新成果。此外,文章还指出了固体MOPA激光器在高功率、高效率条件下光束质量优化的难点,并展望了未来可能的研究方向和技术突破。
