This study reports a new optically addressed spatial light modulator (OASLM) structure based on bilateral-sapphire substrates with an air gap that exhibits high-average-power laser resistance. The resistance of traditional OASLMs to high-average-power laser irradiation is primarily affected by the high absorption of the transparent conductive film and low thermal conductivity of the substrate. Thermodynamic simulations indicated that the thermal conductivity of a sapphire substrate was significantly higher than that of K9 glass. Using sapphire as the substrate significantly reduced the temperature increase of indium tin oxide. An OASLM based on this structure, without any auxiliary cooling measures, exhibited a higher high-average-power laser resistance (170 W/cm2) than that of a K9 glass OASLM (9 W/cm2).

At the low-coherence Kunwu laser facility with a 0.6% bandwidth, we experimentally studied the laser absorption efficiency of laser–target coupling at intensities of (3–5) × 1014 W cm–2. To characterize side scattering across a wide angular range, we developed a novel radiochromic film-based diagnostic system, which enables continuous spatial mapping over approximately π steradians for the first time. The results indicate a substantial reduction in total loss rate (by more than three times) when compared to a monochromatic laser. We focused on analyzing the influence of laser bandwidth on stimulated Brillouin scattering and stimulated Raman scattering (SRS). Notably, we found that the broadband laser enhances SRS at high intensities, which is contrary to the results obtained at low intensities. These results highlight the role of bandwidth as a quantitative control parameter for improving laser–plasma coupling, which is of particular significance for advancing direct-drive inertial confinement fusion.

With the advancement of high-intensity laser (HIL) technology, laser-induced plasma can produce short-lived nuclear isomers, which hold significant research value in fields such as nuclear-excitation mechanisms, nuclear clocks and radioactive medicine. However, due to intense electromagnetic pulses (EMPs) and X-rays, the detection of the short-lived isomers is still challenging today. To address this, an optical-fiber-coupled scintillator detection method is proposed in this study. The method can overcome the dilemma that traditional real-time detection methods face when struggling with the complex electromagnetic and radiation environment generated by HIL experiments, enabling real-time detection of characteristic signals on the nanosecond time scale during experiments. Employing a PW-level femtosecond laser-pumping ${}^{83}$Kr to the $7/2+$ metastable state, which has a half-life of 156.94 ns, the de-excitation gamma-rays were detected successfully by the proposed detection system for the first time. This method addresses critical challenges in EMP-dominated HIL environments, enables investigations of ultra-fast nuclear processes and further advances experiments related to high-repetition-rate intense lasers.

Nd,Y:CaF2 (NYCF) crystals are exceptional gain materials for high-power laser drivers; however, laser-induced damage remains a substantial challenge that restricts their broader application. In this study, by establishing an in situ testing system for photothermal weak absorption and the laser-induced damage threshold (LIDT), the relationship between the photothermal weak absorption characteristics of NYCF and its LIDTs was analyzed. A fully connected neural network was employed to facilitate deep learning of these relationships, thereby enabling non-destructive evaluation of NYCF via photothermal weak absorption. Moreover, this study examined both the effect of spot size during testing and the influence of crystal orientation on the evaluation outcomes. The underlying mechanisms were further elucidated by investigating NYCF’s thermal mechanical properties and damage characteristics. This work not only offers a rapid, non-destructive method for evaluating the laser damage resistance of NYCF using artificial intelligence but also enhances the understanding of its damage mechanisms.

We present a novel, compact resonator design for large-mode thin-disk lasers, producing 300 W average output power at a 1-kHz repetition rate within a cavity length of less than 5 m. High beam quality with M2x = 1.06 and M2y = 1.15 is achieved by breaking conventional mode-matching ratios and fully exploiting the disk’s soft-aperture effect. In this work, an ytterbium-doped yttrium aluminum garnet thin-disk resonator is shown to produce fundamental transverse mode lasing with a mode size approaching or surpassing the pump spot dimension. Theoretical analysis demonstrates that the proposed cavity configuration enables a thin-disk regenerative amplifier to deliver pulse energy exceeding 200 mJ at 1 kHz repetition rate with excellent beam quality.

Spectral broadening via phase modulation is widely employed in high-power laser systems to suppress transverse-stimulated Brillouin scattering and improve beam uniformity. However, nonuniform spectral transmittance and group velocity dispersion can induce frequency modulation-to-amplitude modulation (FM-to-AM), threatening the safety of large-aperture optics. Current monitoring techniques rely on high-speed oscilloscopes and wavelength conversion, thereby increasing the cost and complexity. This study presents a real-time FM-to-AM detection method based on a dual-comparator delay-unlocked detection architecture. The system employs a high-speed photodetector, low-noise amplifier, envelope detection and delay-unlocked dual comparator. The module reliably measures modulation depths from 1.27% to 19.15% for pulses with a rise time of less than 60 ps and a modulation frequency of 20 GHz. This compact, low-cost and modular design enables robust FM-to-AM monitoring without high-speed oscilloscopes, facilitating real-time feedback and enhancing operational stability in large-scale laser drivers, while offering scalability for multi-channel deployment in future inertial confinement fusion facilities.

We propose a method for the cut-off of stimulated rotational Raman scattering (SRRS) in high-power lasers after long-distance propagation via a transmission volume Bragg grating (VBG). The VBG with both spectral and angular selectivity was designed, and its application as a near-field spatial filter for SRRS cut-off was analyzed. The results show that the spectral selectivity of the VBG enables effective separation of pump light and Stokes light in the near-field, and also improves the beam quality by filtering out high-frequency components of the pump light. This method can provide a novel and effective approach for suppressing nonlinear effects and controlling the beam quality of high-power lasers.

We report a high-power, high-repetition-rate, Yb-doped fiber femtosecond master-oscillator power-amplifier (MOPA) system. Based on an all-fiber-based chirped pulse amplification configuration comprising a Yb fiber mode-locked seed source, a five-stage repetition-rate multiplier, three Yb-doped fiber amplifiers and a pulse compressor, the MOPA system yielded 1.06 kW of femtosecond pulsed output at 1040 nm with a pulse duration of 356 fs at a repetition rate of 1.83 GHz. Furthermore, a modified seed source incorporating spectral reshaping and additional pulse stretching enabled an improved compressed pulse shape with significantly reduced sidelobes, leading to a shorter pulse duration of 275 fs at the maximum output power. The prospects for a further increase in power and energy via this approach are considered.

High-energy vortex beams with transverse orbital angular momentum (TOAM) have significant applications in many fields. However, generating such beams with well-defined spatiotemporal (ST) field structures at energies beyond extreme ultraviolet is still a major challenge. Here, we demonstrate the generation of coherent X-ray spatiotemporal optical vortices (STOVs) with definitive mode-resolved, ST field-level structures through nonlinear Thomson scattering of a near-infrared STOV laser pulse by a relativistic electron beam in a nanometer-scale thickness. Our far-field time-domain radiation simulations confirm that the generated X-ray harmonics are STOV pulses with well-defined STOV structures, where the vortex charge scales linearly with the harmonic order, in accordance with TOAM conservation. The emission is highly collimated within approximately 4 mrad. The formation of coherent STOV structures requires tight temporal synchronization, spatial confinement and phase matching of the radiation fields from individual electrons in the electron beam. Excessive laser beam sizes induce spectral broadening and phase mismatches, which degrade coherence and suppress the emergence of well-defined STOV harmonics. This study presents a new approach for generating highly collimated X-ray STOVs, with potential applications in nuclear physics, ultrafast dynamics and structured light–matter interactions at the nanoscale.

We present a high-brightness, nanosecond pulsed blue laser source at 476.8 nm through efficient quadruple-harmonic generation from a thulium-doped yttrium lithium fluoride (Tm:YLF) master oscillator power amplifier operating at 1.9 μm. The fundamental-frequency stage produces 42 mJ pulses at 1907.3 nm with a narrow linewidth of 0.19 nm at 1 kHz. Through cascade second-harmonic generation using low-walk-off lithium triborate crystals, we achieve 10.52 mJ blue laser pulses with 16.1 ns duration, corresponding to a peak power of 0.65 MW and exhibiting excellent energy stability of 0.47%. The system maintains exceptional beam quality (M2x = 1.46, M2y = 1.27) at maximum output power, attributed to the negative thermal-optical properties of the Tm:YLF crystal, end-pumped amplification architecture and optimized nonlinear conversion. This work demonstrates a compact and efficient route to high-brightness (~2.49 GW·cm–2·sr–1) pulsed blue laser emission, which is particularly suitable for advanced marine scientific applications including underwater LiDAR and communication systems.

We propose a new compressor geometry – a full-aperture two-grating slanted-groove compressor (F2SC), consisting of two parallel Littrow-mounted gratings with slanted grooves. The angle of the slanting is chosen so as to ensure decoupling of the input and output beams. The gratings and the beam on the first grating have the same size. Optimal parameters of this and other previously proposed compressor geometries are found analytically, considering restrictions not only on the grating length but also on its height. It is shown that, similar to a full-aperture two-grating Treacy compressor (F2TC), the F2SC provides maximum power and focal intensity. The advantages of these geometries are the absence of hot spots on the second (last) grating due to beam smoothing. Power above 160 PW and focal intensity up to 5.5 × 1024 W/cm2 at the F/2 parabola seem quite achievable with the grating sizes of 150 cm × 122 cm for the F2SC and 162 cm × 108 cm for the F2TC. Another advantage of the F2SC is the potential possibility of using multilayer dielectric gratings.

Power scaling of neodymium (Nd)-doped single-frequency fiber lasers (SFFLs) operating at approximately 900 nm has been fundamentally constrained by dominant emission of approximately 1060 nm, with previous demonstrations limited to below 3 W. Here, we demonstrate a 910 nm single-mode Nd-doped SFFL system that achieves a record output power of over 30 W employing homemade Nd-doped silica fiber (NDF), while preserving exceptional 49 dB suppression of competing emission of approximately 1060 nm. The laser system originates from a distributed Bragg reflector single-frequency (SF) oscillator with 11 mW output power, which is subsequently amplified to 31.1 W through three polarization-maintaining (PM) amplification stages utilizing PM 10/125 μm NDF. To the best of our knowledge, this represents the highest power achieved for Nd-doped SFFLs in this spectral region. The output exhibits excellent beam quality (Mx2 = 1.03, My2 = 1.05) and narrow linewidth (10.2 kHz). These results validate that the homemade PM 10/125 μm NDF can be employed in intermediate and main amplifiers in all-fiber SF master oscillator power amplifier systems at approximately 900 nm.

Deep learning (DL) has been applied to phase control in coherent beam combining (CBC) recently. However, existing DL-based approaches for filled-aperture CBC essentially convert the phase-locking path into tiled-aperture schemes. Consequently, common-path phase locking in DL-based filled-aperture CBC remains unrealized. Common-path refers to a phase-locking scheme in which the phase information is extracted from the combined beam after the same combining system. In this paper, a common-path phase-locking method is proposed. By exploiting the intrinsic nonuniformity, each laser source is effectively labeled, enabling a mapping between the combined speckle and the multi-source phase. A neural network is employed to reconstruct the phase. Simulations with 25-channel CBC demonstrate a phase-locking accuracy of up to λ/39. Notably, it remains effective under dynamic phase disturbances. Our work presents a common-path phase-locking approach based on a neural network for filled-aperture CBC, which can offer a new solution for the field.

A spatiotemporal optical vortex (STOV) with transverse orbital angular momentum can induce some novel properties in high-energy-density physics. However, the current STOV pulse energy is limited to the mJ level, which greatly hinders the development of the research field of relativistic laser–matter interaction. Combined with the large-scale grating pair in high-peak-power laser facilities, a method for generating STOVs with ultra-high intensity of up to 1021 W/cm2 is proposed. The numerical simulation proves that a wave packet with 60 fs duration and 83 J energy can be generated in the far-field, maintaining an integral spatiotemporal vortex construction. Simultaneously, STOVs with 1.1 mJ single-pulse energy were obtained in a proof-of-principle experiment, and characterized by a home-made measuring device.

We demonstrate the effective compensation of carrier envelope phase (CEP) slip in a high-power femtosecond laser using a machine-learning (ML)-based control scheme. The compensation is achieved through fine dispersion tuning guided by a recurrent neural network (RNN) that predicts the temporal evolution of CEP slip, combined with a reinforcement-learning (RL) scheme that determines the optimal corrective actions. With this RNN+RL framework, the integrated CEP noise is reduced by more than a factor of two compared with a conventional proportional–integral–derivative controller. The proposed ML-based control methodology provides a versatile tool for stabilizing and optimizing various parameters in high-power laser systems.

To mitigate inhomogeneous thermal and stress effects caused by multi-pulse accumulation in laser–material interactions, we propose an all-optical strategy to generate a structured beam, termed a ‘drill-like laser’, featuring a petal-shaped intensity profile with stochastic rotation by shot-to-shot control. The strategy involves generating collinear signal and idler pulses carrying conjugated orbital angular momenta via optical parametric amplification (OPA). The pulses then interfere with each other to form a beam with petal-shaped intensity structure, whose orientation is governed by their carrier-envelope phase (CEP) difference. The strategy is further implemented with a dual-stage OPA system pumped by an 800-Hz–30-fs–800-nm femtosecond laser, where the CEP difference is directly controlled by the pump CEP. Experimentally, a drill-like laser at 1.6 μm is demonstrated with stochastic shot-to-shot intensity rotation, resulting from the shot-to-shot random fluctuation of the pump CEPs, which has been validated using dual-line pump–probe detection via sum-frequency generation. Crucially, since the interference arises from two beams with free-space eigenmodes, rather than angular-dispersion-based spatiotemporal coupling, the drill-like laser maintains high propagation stability and is scalable in power by conventional laser amplification, holding great potential for applications in precision laser processing and other high-field scenarios.

Surface defects on fused silica optics significantly limit their laser-induced damage resistance under ultraviolet pulsed laser irradiation, yet quantitative correlations between defect parameters and damage thresholds remain scarce. This study is the first to perform multimodal detection and correlation analysis of laser-induced damage initiated at real defects on fused silica. Scratches were characterized by scattered light intensity, width and fluorescence intensity, and correlated with the damage-onset fluence (DOF). Results show trailing indent scratches (1.9–8.8 μm wide) have DOFs of 1.27–13.2 J/cm2, while plastic continuous scratches (0.4–5.8 μm wide) exhibit higher DOFs of 12.3– 22.0 J/cm2. Fluorescence intensity strongly negatively correlates with DOF (p < 0.001), as do scratch width and fluorescence intensity at α = 0.01 (p < 0.01). These findings establish scratch width and fluorescence intensity as quantitative damage precursors, advancing surface quality assessment for high-energy laser optics.

We present the characterization of intensity distributions and the beam wavefront along the caustic of an iodine photodissociation laser beam at the Prague Asterix Laser System. Its $700\;\mathrm{J},300\;\mathrm{ps}$ laser pulse was attenuated by neutral-density optical filters and focused by an $f/2.2$ aspherical lens. In multiple planes at and around the focus position ($\pm 7\times \mathrm{Rayleigh}\kern0.17em \mathrm{length}$), we measured fluence distributions by far-field imaging with a nonlinearity-corrected camera. We used these measurements to retrieve the beam wavefront by a phase retrieval algorithm with dynamic input–output mixing. We then propagated the beam to the focus position and to the lens position. The calculated peak intensity at the focus position was $7.9\times {10}^{18}\;\mathrm{W}/{\mathrm{cm}}^2$, and $300\;\mathrm{J}$ (43% of the pulse energy) was contained within the intensity region above the relativistic intensity threshold of $0.8\times {10}^{18}\;\mathrm{W}/{\mathrm{cm}}^2@1315.2\;\mathrm{nm}$.

We review prevalent fabrication techniques for targets used in high-power and high-intensity single-beam laser experiments, emphasizing their applications and performance. Solid targets include free-standing metallic and carbon films of various thicknesses for particle acceleration studies involving proton and carbon beams and micro-/nano-structured surfaces, as well as near-critical-density materials, such as foams, which enhance laser absorption and coupling, and boron targets for proton–boron fusion experiments. The resulting gamma and proton beams enable applications in isomer production, proton therapy, societal applications and fundamental studies. The use of gas targets for electron acceleration via the laser wakefield acceleration mechanism is discussed, as are cryogenic clusters undergoing Coulomb explosion. Finally, liquid, cryogenic and tape target systems are presented as high-repetition-rate and application-oriented solutions, offering high reproducibility and long-term operation.