Spectrally tunable high-power Yb:fiber chirped-pulse amplifier
Valentina Shumakova, Vito F. Pecile, Jakob Fellinger, Michael Leskowschek, P. E. Collin Aldia, Aline S. Mayer, Lukas W. Perner, Sarper Salman, Mingqi Fan, Prannay Balla, Stéphane Schilt, Christoph M. Heyl, Ingmar Hartl, Gil Porat, and Oliver H. Heckl
Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability, high peak and average power levels, pulse duration, and spectral bandwidth. For instance, spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser, and therefore high average power, pulse duration of a few tens of fs, and maximal available spectral bandwidth. Contrarily, the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating limitations. Here we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification (CPA) to the requirements of different nonlinear frequency converters while preserving the low-phase-noise (PN) properties of the system. To achieve spectral tunability, we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA system. The CPA system delivers 100 W of average power at a repetition rate of 132.4 MHz. While gaining control over the spectral properties, we preserve the relative-intensity-noise and PN properties of the system. The high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation (full width at half maximum of ∼11 nm, compressed pulse duration of 230 fs) or a spectrum ideal for highly nonlinear processes such as high-harmonic generation (-10 dB level of >50 nm, transform-limited pulse duration of ∼65 fs).Tailoring the properties of the driving laser to the need of applications often requires compromises among laser stability, high peak and average power levels, pulse duration, and spectral bandwidth. For instance, spectroscopy with optical frequency combs in the extreme/visible ultraviolet spectral region requires a high peak power of the near-IR driving laser, and therefore high average power, pulse duration of a few tens of fs, and maximal available spectral bandwidth. Contrarily, the parametric conversion efficiency is higher for pulses with a duration in the 100-fs range due to temporal walk-off and coating limitations. Here we suggest an approach to adjust the spectral characteristics of high-power chirped-pulse amplification (CPA) to the requirements of different nonlinear frequency converters while preserving the low-phase-noise (PN) properties of the system. To achieve spectral tunability, we installed a mechanical spectral shaper in a free-space section of the stretcher of an in-house-developed ytterbium-fiber-based CPA system. The CPA system delivers 100 W of average power at a repetition rate of 132.4 MHz. While gaining control over the spectral properties, we preserve the relative-intensity-noise and PN properties of the system. The high-power CPA can easily be adjusted to deliver either a spectrum ideal for mid-IR light generation (full width at half maximum of
- Aug. 17, 2026
- Photonics Research
- Vol. 10, Issue 10, 2309 (2022)
- DOI：10.1364/PRJ.465883
Multi-beam structured light single-pixel imaging
Ziwen Long, Xinyu Fan and Zuyuan He
By reconstructing 2D images of an object using temporal signals captured by a single-pixel photodetector (PD), single-pixel imaging (SPI) technology offers a cost-effective alternative to traditional focal-plane-array imaging systems. This advantage is particularly significant in some non-visible spectral bands, where manufacturing PD arrays is prohibitively expensive. However, conventional SPI systems, which employ single-beam structured light, suffer from limited imaging speeds. In this paper, we propose a multi-beam structured light SPI (MSL-SPI) system. It combines the spatial modulation scheme and the parallel measurement capabilities of a dual-comb interferometer. Compared with traditional SPI systems, the imaging speed can be significantly improved without compromising the space-bandwidth product. Experiments were performed to verify the system, which achieved simultaneous spatial modulation on nine light beams, improving the imaging speed by approximately an order of magnitude. Sub-second temporal resolution and a pixel count of 12×12 were realized using a standard digital micromirror device (DMD) with a refresh rate of only 60 Hz. Furthermore, dynamic imaging with a frame rate of 30 frames per second (FPS) and a pixel count of 6×6 was demonstrated under a 240 Hz refresh rate of the DMD. These results showcase the potential of MSL-SPI for faster and more efficient SPI systems.By reconstructing 2D images of an object using temporal signals captured by a single-pixel photodetector (PD), single-pixel imaging (SPI) technology offers a cost-effective alternative to traditional focal-plane-array imaging systems. This advantage is particularly significant in some non-visible spectral bands, where manufacturing PD arrays is prohibitively expensive. However, conventional SPI systems, which employ single-beam structured light, suffer from limited imaging speeds. In this paper, we propose a multi-beam structured light SPI (MSL-SPI) system. It combines the spatial modulation scheme and the parallel measurement capabilities of a dual-comb interferometer. Compared with traditional SPI systems, the imaging speed can be significantly improved without compromising the space-bandwidth product. Experiments were performed to verify the system, which achieved simultaneous spatial modulation on nine light beams, improving the imaging speed by approximately an order of magnitude. Sub-second temporal resolution and a pixel count of
- Aug. 13, 2026
- Advanced Imaging
- Vol. 3, Issue 5, 051001 (2026)
- DOI：10.3788/AI.2026.10019
EUV-IR beam separator based on laser-fabricated hollow waveguides
Anna Gabriella Ciriolo, Gabriele Crippa, Stavroula Vovla, Kamal Abedin, Michele Devetta, Davide Faccialà, Andrea Annunziata, Pasquale Barbato, Luca Poletto, Fabio Frassetto, Roberto Osellame, Caterina Vozzi, Salvatore Stagira, and Rebeca Martínez Vázquez
Leveraging the natural axial confinement of coherent extreme ultraviolet (EUV) light generated via the high-order harmonic generation process, we demonstrate the spatial separation of EUV and the driving infrared (IR) beams through hollow-core microchannels embedded in a laser machine glass device. This structure enables broadband EUV transmission while attenuating the collinear IR by 2 orders of magnitude. In addition, we explore the potential of integrated photonic architectures based on EUV-guiding hollow structures, laying the foundation for a new class of compact, palm-top devices for EUV and soft X-ray applications.Leveraging the natural axial confinement of coherent extreme ultraviolet (EUV) light generated via the high-order harmonic generation process, we demonstrate the spatial separation of EUV and the driving infrared (IR) beams through hollow-core microchannels embedded in a laser machine glass device. This structure enables broadband EUV transmission while attenuating the collinear IR by 2 orders of magnitude. In addition, we explore the potential of integrated photonic architectures based on EUV-guiding hollow structures, laying the foundation for a new class of compact, palm-top devices for EUV and soft X-ray applications.
- Aug. 12, 2026
- Advanced Photonics Nexus
- Vol. 5, Issue 4, 046025 (2026)
- DOI：10.1117/1.APN.5.4.046025
Physics-guided deep unfolding network for snapshot 3D imaging using double-helix point spread function
Gang Qu, Pengwei Wang, Xing Liu, Haomiao Zhang, Mengyuan Liu, Zhentao Liu, and Xin Yuan
Point spread function (PSF) engineering is a promising approach for passive, snapshot 3D imaging with a single detector. A widely used technique is the double-helix PSF (DH-PSF), which employs a specialized phase mask at the pupil plane to modulate incident light, generating rotationally varying PSFs with defocus. By leveraging a precalibrated depth-dependent PSF model, the depth information of the target surface can be recovered from a snapshot measurement. However, existing reconstruction algorithms often lack efficiency and accuracy, primarily due to the block-wise processing of conventional methods or the failure to incorporate physical priors in end-to-end neural networks. To address these limitations, we propose a physics-guided deep unfolding network (PG-DUN) for snapshot 3D imaging with DH-PSFs. By explicitly embedding the imaging model into the deep neural network, our DUN can naturally reconstruct the 2D image and depth map simultaneously, contributing to more accurate and efficient reconstruction than previous approaches. The feasibility and effectiveness of the proposed method are validated through extensive experiments on simulated and real-world data. The proposed method can serve as a prototype for a deep learning-based reconstruction model in similar deconvolution tasks. Its key innovation—an accelerated deconvolutional gradient descent design—functions as a plug-and-play component that enhances the reconstruction accuracy of any deep neural network with negligible added computational cost.Point spread function (PSF) engineering is a promising approach for passive, snapshot 3D imaging with a single detector. A widely used technique is the double-helix PSF (DH-PSF), which employs a specialized phase mask at the pupil plane to modulate incident light, generating rotationally varying PSFs with defocus. By leveraging a precalibrated depth-dependent PSF model, the depth information of the target surface can be recovered from a snapshot measurement. However, existing reconstruction algorithms often lack efficiency and accuracy, primarily due to the block-wise processing of conventional methods or the failure to incorporate physical priors in end-to-end neural networks. To address these limitations, we propose a physics-guided deep unfolding network (PG-DUN) for snapshot 3D imaging with DH-PSFs. By explicitly embedding the imaging model into the deep neural network, our DUN can naturally reconstruct the 2D image and depth map simultaneously, contributing to more accurate and efficient reconstruction than previous approaches. The feasibility and effectiveness of the proposed method are validated through extensive experiments on simulated and real-world data. The proposed method can serve as a prototype for a deep learning-based reconstruction model in similar deconvolution tasks. Its key innovation—an accelerated deconvolutional gradient descent design—functions as a plug-and-play component that enhances the reconstruction accuracy of any deep neural network with negligible added computational cost.
- Aug. 12, 2026
- Advanced Photonics Nexus
- Vol. 5, Issue 5, 056024 (2026)
- DOI：10.1117/1.APN.5.5.056024
Towards direct nonlinear compression of energetic sub-nanosecond pulses to the ultrafast regime
Gaspard Beaufort, Nayla Jimenez, Gunnar Arisholm, Victor Hariton, Ayhan Tajalli, Ingmar Hartl, Anne-Lise Viotti, and Marcus Seidel
Applications of terawatt-class lasers can enormously benefit from pulse trains with kHz repetition rates. The associated unprecedented combinations of peak and average powers require the development of new concepts for scalable ultrashort pulse generation. Through comprehensive simulations, we analyze spectral broadening of 300-ps, 100-mJ pulses in multi-pass cells and anti-resonant hollow-core fibers towards the fs regime. We introduce an 11-mirror cell geometry that can deliver kilometer-scale nonlinear interaction lengths. We experimentally demonstrate nearly 300 passes in such a cell. This enables at least four times larger B-integral to peak power ratios than in previously reported spectral broadening experiments with air-filled multi-pass cells. These results highlight the strong potential of advanced multi-pass cell designs to reach unprecedented broadening factors. The proposed scheme can efficiently transform industrially mature high-power, high-energy lasers into unique ultrafast sources.Applications of terawatt-class lasers can enormously benefit from pulse trains with kHz repetition rates. The associated unprecedented combinations of peak and average powers require the development of new concepts for scalable ultrashort pulse generation. Through comprehensive simulations, we analyze spectral broadening of 300-ps, 100-mJ pulses in multi-pass cells and anti-resonant hollow-core fibers towards the fs regime. We introduce an 11-mirror cell geometry that can deliver kilometer-scale nonlinear interaction lengths. We experimentally demonstrate nearly 300 passes in such a cell. This enables at least four times larger B-integral to peak power ratios than in previously reported spectral broadening experiments with air-filled multi-pass cells. These results highlight the strong potential of advanced multi-pass cell designs to reach unprecedented broadening factors. The proposed scheme can efficiently transform industrially mature high-power, high-energy lasers into unique ultrafast sources.
- Aug. 11, 2026
- High Power Laser Science and Engineering
- Vol. 14, Issue 4, 04000e69 (2026)
- DOI：10.1017/hpl.2026.10156
Enhanced 
fusion and 
particle production from laser-irradiated nanowire arrays
fusion and 
particle production from laser-irradiated nanowire arraysQian Wang, Hairong Huang, Wenjing Fei, Jie Lin, Qian Dong, Huizhong Deng, Yun Yuan, and Wen Luo
Proton–boron ( ${\mathrm{p}}^{11}\mathrm{B}$ ) fusion provides a unique pathway for generating energetic $\alpha$ particles with a low associated neutron background. In this work, we investigate, through particle-in-cell Monte Carlo (PIC-MC) simulations, an enhanced ${\mathrm{p}}^{11}\mathrm{B}$ fusion and $\alpha$ particle production in laser-irradiated nanowire arrays (NWAs). A Monte Carlo ${\mathrm{p}}^{11}\mathrm{B}$ fusion module is first implemented within the EPOCH framework, which helps to reliably simulate the ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma dynamics. Benchmark tests on the $\alpha$ particle generation in ${\mathrm{p}}^{11}\mathrm{B}$ fusion reactions are performed. The results agree well with both the available experimental and theoretical data, thus validating the implemented ${\mathrm{p}}^{11}\mathrm{B}$ fusion module. This development is then used to study the ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma dynamics and the resulting production of $\alpha$ particles in the NWA targets composed of octadecaborane, in which Bayesian optimization is performed to search for an optimal laser intensity and NWA configuration. Two-dimensional PIC-MC simulations demonstrate that the NWA targets can produce a flux of energetic $\alpha$ particles approximately two orders of magnitude greater than that of a planar target. This enhancement is mainly attributed to an efficient ion acceleration by sheath fields. It is demonstrated that the proposed optimization framework represents a reliable and efficient tool for studying laser-driven ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma physics, while providing valuable insights and practical guidance for optimizing NWA targets toward higher reaction yields.Proton–boron ( ${\mathrm{p}}^{11}\mathrm{B}$ ) fusion provides a unique pathway for generating energetic $\alpha$ particles with a low associated neutron background. In this work, we investigate, through particle-in-cell Monte Carlo (PIC-MC) simulations, an enhanced ${\mathrm{p}}^{11}\mathrm{B}$ fusion and $\alpha$ particle production in laser-irradiated nanowire arrays (NWAs). A Monte Carlo ${\mathrm{p}}^{11}\mathrm{B}$ fusion module is first implemented within the EPOCH framework, which helps to reliably simulate the ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma dynamics. Benchmark tests on the $\alpha$ particle generation in ${\mathrm{p}}^{11}\mathrm{B}$ fusion reactions are performed. The results agree well with both the available experimental and theoretical data, thus validating the implemented ${\mathrm{p}}^{11}\mathrm{B}$ fusion module. This development is then used to study the ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma dynamics and the resulting production of $\alpha$ particles in the NWA targets composed of octadecaborane, in which Bayesian optimization is performed to search for an optimal laser intensity and NWA configuration. Two-dimensional PIC-MC simulations demonstrate that the NWA targets can produce a flux of energetic $\alpha$ particles approximately two orders of magnitude greater than that of a planar target. This enhancement is mainly attributed to an efficient ion acceleration by sheath fields. It is demonstrated that the proposed optimization framework represents a reliable and efficient tool for studying laser-driven ${\mathrm{p}}^{11}\mathrm{B}$ fusion plasma physics, while providing valuable insights and practical guidance for optimizing NWA targets toward higher reaction yields.
- Aug. 11, 2026
- High Power Laser Science and Engineering
- Vol. 14, Issue 3, 03000e56 (2026)
- DOI：10.1017/hpl.2026.10131
Spatio-temporal characterization of a petawatt laser using deterministic speckle patterns | Editors' Pick
Jannik Esslinger, Sebastian Wiest, Nils Weiße, Slava Smartsev, Stefan Karsch, and Andreas Döpp
We present a deterministic method for the spatio-spectral characterization of intense ultrashort laser pulses via far-field speckle analysis. By mapping vacuum propagation to a linear forward model, we replace slow, error-prone iterative algorithms with a direct least-squares minimization. This enables high-speed retrieval of spectrally resolved wavefronts with rigorous uncertainty quantification. Demonstrated at the ATLAS-3000 petawatt facility, our in situ architecture utilizes only a pinhole mask for both attenuation and speckle generation. By eliminating complex downstream optics and minimizing systematic errors, this approach provides a robust, real-time diagnostic essential for the optimization of high-intensity lasers.We present a deterministic method for the spatio-spectral characterization of intense ultrashort laser pulses via far-field speckle analysis. By mapping vacuum propagation to a linear forward model, we replace slow, error-prone iterative algorithms with a direct least-squares minimization. This enables high-speed retrieval of spectrally resolved wavefronts with rigorous uncertainty quantification. Demonstrated at the ATLAS-3000 petawatt facility, our in situ architecture utilizes only a pinhole mask for both attenuation and speckle generation. By eliminating complex downstream optics and minimizing systematic errors, this approach provides a robust, real-time diagnostic essential for the optimization of high-intensity lasers.
- Aug. 11, 2026
- High Power Laser Science and Engineering
- Vol. 14, Issue 3, 03000e55 (2026)
- DOI：10.1017/hpl.2026.10146
Gradient dielectric engineering for tailored third-order optical nonlinearity
Pengyi Liu, Zhiqi Dai, Ulrich Kentsc, Shengqiang Zhou, Xiaoli Sun, and Feng Chen
Fused silica is an indispensable optical substrate for modern photonics, featuring excellent transmittance, high stability, and superior complementary metal-oxide-semiconductor (CMOS) compatibility, but its weak intrinsic nonlinearity limits applications in wavelength-dependent nonlinear regulation and ultrafast photonic switching. Here, Ag/Y sequential ion implantation is employed to incorporate Ag nanoparticles (Ag NPs) and Y dopants into silica. Inhomogeneous Y doping modulates the local dielectric environment around the nanoparticles and induces a resonance redshift, enabling tunable nonlinear optical properties. The ion-implantation-broadened absorption spectrum also enables a distinct nonlinear response at 1030 nm. This study opens a promising route for developing high-performance ultrafast photonic devices.Fused silica is an indispensable optical substrate for modern photonics, featuring excellent transmittance, high stability, and superior complementary metal-oxide-semiconductor (CMOS) compatibility, but its weak intrinsic nonlinearity limits applications in wavelength-dependent nonlinear regulation and ultrafast photonic switching. Here, Ag/Y sequential ion implantation is employed to incorporate Ag nanoparticles (Ag NPs) and Y dopants into silica. Inhomogeneous Y doping modulates the local dielectric environment around the nanoparticles and induces a resonance redshift, enabling tunable nonlinear optical properties. The ion-implantation-broadened absorption spectrum also enables a distinct nonlinear response at 1030 nm. This study opens a promising route for developing high-performance ultrafast photonic devices.
- Aug. 11, 2026
- Laser and Particle Beams
- Vol. 44, Issue 4, S1004 (2026)
- DOI：10.3788/LPB.2026.S1004
Radiation source position manipulation of echo-enabled harmonic generation in a long undulator line at the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility
Shenhui Zhang, Haiyang Li, Yixuan Liu, and Tao Liu
The longitudinal output position of the radiation source in an X-ray free-electron laser (XFEL) significantly affects the design and performance of downstream beamlines, including photon transport efficiency and focusing quality at the experimental station. For external-seeded free-electron lasers (FELs) such as echo-enabled harmonic generation (EEHG), the saturation point is typically located farther upstream than in the self-amplified spontaneous emission (SASE) configuration, which imposes constraints on beamline layout flexibility and final spot size. To address this issue for the FEL-II line at the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility (SHINE), we propose two novel methods to shift the EEHG radiation source downstream: a density modulation delay scheme and a direct-seeding combined scheme. Detailed simulations of the 30th harmonic EEHG demonstrate that both approaches preserve high saturation power and excellent longitudinal coherence while relocating the radiation source position downstream by several tens of meters, closer to the undulator exit. Furthermore, we have performed start-to-end simulations and conducted qualitative analyses of collective and higher-order effects for the proposed schemes. These methods provide viable solutions for the active manipulation of the radiation source position in long-undulator-based seeded FELs, thereby enhancing operational adaptability and enabling optimized beamline designs for a wide range of user experiments at large-scale XFEL facilities.The longitudinal output position of the radiation source in an X-ray free-electron laser (XFEL) significantly affects the design and performance of downstream beamlines, including photon transport efficiency and focusing quality at the experimental station. For external-seeded free-electron lasers (FELs) such as echo-enabled harmonic generation (EEHG), the saturation point is typically located farther upstream than in the self-amplified spontaneous emission (SASE) configuration, which imposes constraints on beamline layout flexibility and final spot size. To address this issue for the FEL-II line at the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility (SHINE), we propose two novel methods to shift the EEHG radiation source downstream: a density modulation delay scheme and a direct-seeding combined scheme. Detailed simulations of the 30th harmonic EEHG demonstrate that both approaches preserve high saturation power and excellent longitudinal coherence while relocating the radiation source position downstream by several tens of meters, closer to the undulator exit. Furthermore, we have performed start-to-end simulations and conducted qualitative analyses of collective and higher-order effects for the proposed schemes. These methods provide viable solutions for the active manipulation of the radiation source position in long-undulator-based seeded FELs, thereby enhancing operational adaptability and enabling optimized beamline designs for a wide range of user experiments at large-scale XFEL facilities.
- Aug. 11, 2026
- Laser and Particle Beams
- Vol. 44, Issue 4, 10021 (2026)
- DOI：10.3788/LPB.2026.10021
Coherent combination of ultrashort pulses at low repetition rate
Andrei Nazîru, Alice Dumitru, Stefan Popa, Dan Gheorghita Matei, Vlad Andrei Popescu, Andrew Hiroaki Okukura, Daniel Crăcană, Bianca Stan, Lidia Văsescu, Sergiu Rusnac, Marius Gugiu, Vojtech Horny, Paolo Tomassini, Andrei Grădinariu, Christophe Derycke, Olivier Chalus, Răzvan Dabu, Ioan Dăncus, and Daniel Ursescu
Synchronization of common-seed ultrashort pulses from parallel chirped pulse amplification (CPA) and compression systems, with accuracy comparable with the pulse duration, is hindered by the inherent environmental noise present in the laboratory. If the pulses are produced in high-repetition-rate systems, they can be monitored in real-time and their relative delay fluctuations can be efficiently suppressed. However, at lower repetition rates, the laser pulses themselves do not provide the information about the delay for compensation at the required pace. Demonstrated here is the coherent combination of two ultrashort pulses from a dual arm CPA laser system and dual optical compressors at low repetition rate, using an assisting continuous wave laser beam. In this way, the relative delay fluctuations in the common focus of the two pulses reached 325 as root mean square (rms), corresponding to $\lambda /8$ , over 45 minutes of operation at 10 Hz, while their short-term measured stability was 78 as rms, corresponding to $\lambda /34$ , over 100 s.Synchronization of common-seed ultrashort pulses from parallel chirped pulse amplification (CPA) and compression systems, with accuracy comparable with the pulse duration, is hindered by the inherent environmental noise present in the laboratory. If the pulses are produced in high-repetition-rate systems, they can be monitored in real-time and their relative delay fluctuations can be efficiently suppressed. However, at lower repetition rates, the laser pulses themselves do not provide the information about the delay for compensation at the required pace. Demonstrated here is the coherent combination of two ultrashort pulses from a dual arm CPA laser system and dual optical compressors at low repetition rate, using an assisting continuous wave laser beam. In this way, the relative delay fluctuations in the common focus of the two pulses reached 325 as root mean square (rms), corresponding to $\lambda /8$ , over 45 minutes of operation at 10 Hz, while their short-term measured stability was 78 as rms, corresponding to $\lambda /34$ , over 100 s.
- Aug. 11, 2026
- High Power Laser Science and Engineering
- Vol. 14, Issue 3, 03000e58 (2026)
- DOI：10.1017/hpl.2026.10145
OpticsNatural ScienceEngineeringAgricultureMedical ScienceMultidisciplinaryAll Subjects
Journal
Aug. 17, 2026
Submission Open:1 September 2026; Submission Deadline: 1 December 2026
Editor (s): Yuri Kivshar,Zhanghua Han,Maxim Gorkunov,Yongmin Liu,Ivan Fernandez Corbaton
Special Issue on PROton BOron Nuclear fusion: from energy production to medical applicatiOns (2026)
Submission Open:14 July 2026; Submission Deadline: 28 April 2027
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