Laser

A laser-based technology being developed at Adelaide University could soon help authorities detect deadly counterfeit alcohol, expose wine fraud and even identify dangerous chemicals inside sealed bottles – all without opening them.

arXiv:2607.15109v1 Announce Type: new Abstract: Optical frequency combs are key components of several photonics applications including spectroscopy, communications, and ultrafast photonics. A central challenge in frequency-comb photonics is to develop sources whose operating state can be precisely controlled and adapted to different application needs. We introduce frequency comb functionality to a THz metasurface vertical-external-cavity-surface-emitting laser (VECSEL), combining its characteristic high output power and excellent beam quality with a reconfigurable comb output. The source exhibits reversible switching between actively mode-locked 3.5 ps-long pulses and stable frequency-modulated quantum walk comb states. The flexible control of the intermodal phase relation is achieved through careful dispersion engineering via a Gires-Tournois interferometer (GTI) output-coupler combined with resonant RF bias modulation of the metasurface. These results pave the way for on-demand comb

arXiv:2607.13289v1 Announce Type: new Abstract: Laser-based thermal processing, such as laser powder bed fusion, requires tight regulation of the peak surface temperature: heat accumulates where the moving source re-enters previously heated material, driving the temperature out of its process window and causing defects. High-fidelity thermal models capture this physics but are too slow for online optimization, which motivates fast, differentiable, and generalizable surrogates. We develop and validate a complete surrogate-based control pipeline that regulates the maximum surface temperature of a moving laser on a 304-stainless-steel substrate. We also determine conditions under which our surrogate can be trusted inside the control loop by probing its out-of-distribution limits. A key component of our surrogate is a multi-step deep operator network bespoke for moving sources: its branch subnetwork encodes the future power and trajectory (position and velocity) sequence, while its trunk

arXiv:2607.13211v1 Announce Type: cross Abstract: Molybdenum disulfide (MoS$_2$) is a semiconductor whose vibrational and excitonic properties are highly sensitive to layer number and structural disorder. We demonstrate the growth of MoS$_2$ monolayers on inert, electronics-compatible SiO$_2$ substrates using room-temperature pulsed laser deposition (PLD). Control of the process parameters enables tuning from monolayer to multilayer films, which we investigate by multiwavelength Raman spectroscopy. The evolution of the Raman-shift difference between the $E_{2g}^{1}$ and $A_{1g}$ modes, combined with an assessment of defect density, tracks film growth as a function of the number of deposition laser pulses. Although excitonic effects strongly influence the optical response of two-dimensional transition-metal dichalcogenides, experimental reports of symmetry-selective exciton-phonon coupling remain limited. We provide experimental evidence of symmetry-dependent exciton-phonon coupling in

arXiv:2607.14017v1 Announce Type: new Abstract: Bio-heat transfer models play a fundamental role in predicting temperature fields during laser-induced thermal therapy (LITT). Among continuum bio-heat transfer models, the Pennes equation remains the most widely adopted formulation. However, by representing blood perfusion as an isotropic volumetric source, it neglects the directional transport of thermal energy associated with blood flow. The Wulff model overcomes this limitation by incorporating blood averaged enthalpy transport directly into the heat flux. Despite its physical significance, the derivation of the Wulff formulation and the assumptions required to obtain its governing equation remain only briefly discussed in the original work. The aim of the present work is twofold. First, the physical formulation originally proposed by Wulff is revisited in order to clarify its derivation and the assumptions required to obtain the governing equation. In particular, the physical origin

arXiv:2607.13585v1 Announce Type: new Abstract: Compact deuterium--deuterium (D--D) neutron sources can provide controllable irradiation fields for lithium-blanket studies, although their broad joint energy and angle distributions differ from the conventional $2.45$~MeV isotropic representation. We couple particle-in-cell (PIC) simulations of target-normal-sheath-accelerated deuterons with a thick-target $D(d,n)^{3}$He source model and Monte Carlo neutron transport. For natural lithium, the seven two-dimensional sources change tritium production per source neutron by $-2.5\%$ to $+54.1\%$ relative to the ideal source. The matched three-dimensional calculation gives an increase of $43.5\%$ and lowers the corresponding ratio from $1.5406$ to $1.4350$. Source substitutions show that the difference is predominantly spectral, since the real spectrum alone gives a factor of $1.4199$, while using the real neutron emission directions in place of isotropic emission adds only a further factor

arXiv:2607.13145v1 Announce Type: new Abstract: Magneto-optical traps (MOTs) are a workhorse technology for neutral-atom quantum sensing, simulation, and computing. Here, we demonstrate a MOT optimized for inertial quantum sensing and precision metrology applications. Our MOT traps $4\times10^8$ cesium (Cs) atoms in a robust, modular system that achieves stable operation through two design features: (1) we use diverging cooling laser beams to reduce unwanted reflections and (2) optical elements are mounted in a fiber-coupled, compact, and modular cage rigidly attached to the vacuum chamber. Following polarization-gradient cooling (PGC), the system produces atom samples with temperatures below 10 ${\mu}$K, similar to those achieved in conventional MOTs that use collimated laser beams. In addition, we observe trapping of $2\times10^7$ Cs atoms in a non-conventional MOT geometry, where the cooling laser beams are diagonal to the principal axis of the quadrupole magnetic field.

Treatment with a 1940-nm nonablative fractional laser may modulate biological pathways linked to both skin aging and skin cancer, a new split-face study suggests.

arXiv:2607.12984v1 Announce Type: new Abstract: We report the first demonstration of single-shot particle radiography using a 1-10 GeV laser-wakefield-generated beam of muons, pions, and neutrons. The test objects were imaged ~15 m from the beam source, through dense lead shielding followed by the walls of a building and a truck. The muon content of the beam was directly confirmed using large volume scintillator-based detectors, which recorded particle decay events with timing delays consistent with the muon lifetime. Simulations confirm that the high energy component of the beam transmitted through the test object is nearly entirely composed of muons, directly showing their highly penetrative nature, with a single-shot fluence equivalent to >8 hours of integration of cosmic ray muons near the horizon. Our work establishes single-shot high-energy particle radiography with a laser-wakefield-accelerator-driven source.

arXiv:2607.12843v1 Announce Type: new Abstract: We investigate the Coulomb explosion of ethane (C$_2$H$_6$), propane (C$_3$H$_8$), and \textit{n}-butane (C$_4$H$_{10}$) driven by intense circularly polarized laser pulses using real-time time-dependent density functional theory (RT-TDDFT). The ionization dynamics are benchmarked against those obtained with linearly polarized fields oriented along the $x$, $y$, and $z$ axes at the same peak intensity. Under the laser conditions considered here, circular polarization produces greater ionization than any of the linearly polarized configurations for all three molecules, indicating that the rotating electric field enhances the initial electron-removal stage that triggers Coulomb explosion. Using circularly polarized excitation, we systematically characterize fragmentation thresholds, product distributions, channel branching ratios, and bond-breaking dynamics across the alkane series. Atomic hydrogen is the most abundant fragment in all

arXiv:2607.12451v1 Announce Type: new Abstract: Laser-driven proton acceleration has attracted considerable interest owing to its appealing potential in versatile applications including cancer therapy. Proton energies depend critically on the on-target intensities, yet the detrimental impact of focal spot degradation induced by spatiotemporal couplings on the acceleration remains insufficiently elucidated. In this study, we demonstrate that residual angular chirp (AC), stemming from minor misalignments of the grating compressor in a Petawatt-class laser system, acts as a critical bottleneck for proton acceleration. Experimental results reveal that even around 100 microradians of grating misalignment induces substantial focal-spot elongation and a pronounced reduction in peak intensity. By implementing an in situ spectral-blocking diagnostic, we effectively eliminated the residual AC and restored a near-diffraction-limited focus. This optimization led to a significant recovery of the

arXiv:2607.12439v1 Announce Type: new Abstract: Effects of radiation reaction are considered a key factor for lasers-plasma-interactions at ultra-high intensities, and gaining precise understanding of these phenomena will be crucical for discoveries of novel strong-field QED effects. In this paper we investigate an experimental geometry that allows a direct single-shot measurement of radiation reaction energy losses in high-intensity laser-beam collisions. This is made possible by simultaneous measurements of the pre-collision and post-collision electron beam spectra in a single shot by employing a dedicated 90-degree scattering geometry between the electron beam and the colliding high-power laser. We discuss the principal requirements and design constraints, e.g. for the electron beam divergence and source size. We derive an analytic expression for the correlation between the final particle energy and the scattering angle. Numerical simulations are performed employing both classical

arXiv:2607.11265v1 Announce Type: cross Abstract: Laser-programmable optical anisotropy offers a new route to developing reconfigurable metasurfaces without conventional nanofabrication processes. Here, we demonstrate a lithography-free approach based on spatial control of the crystallographic $c$ axis orientation in tellurium (Te) using pulse laser irradiation. As a proof of concept, we demonstrate a Te metasurface beam splitter by laser-written optical-axis patterning and experimentally confirm that its optical response is in good agreement with theoretical predictions and numerical simulations. By directly programming the local optical anisotropy, this method enables a simple fabrication process while offering the possibility of rewriting and dynamically reconfiguring device functionality. These features make this approach a promising platform for non-resonant active metasurfaces and other reconfigurable flat-optics applications.

arXiv:2607.11553v1 Announce Type: new Abstract: Laser manufacturing has advanced through increasingly precise control of power, pulse duration, repetition rate and scan trajectory, yet the spatial intensity profile of the beam is still usually fixed during light-matter interaction. This constraint limits how energy can be delivered to matter, particularly in processes where melt flow, material removal and surface morphology evolve on comparable time and length scales. Here we introduce drill-bit-inspired laser beams that convert the focal intensity distribution from a passive, static spot into an active, programmable processing tool. By combining cylindrical vector beams with rotational vectorial polarization filtering, we create a near diffraction limited two lobe Hermite-Gaussian focus that continuously spins about the propagation axis and can be reconfigured on demand. We establish two operating regimes, dynamic beam spinning and instantaneous beam-profile shifting, and derive

arXiv:2607.10852v1 Announce Type: new Abstract: The electrical conductivity $\sigma$ of the plasma filament left behind by an ultrashort pulsed laser (USPL) optical pulse after it is geometrically then self-focused in air via the Kerr effect is measured by attenuation of a 3.2 GHz TE$_{10}$ mode within an S-band waveguide through which the filament passes, taking into account the characteristic radius $R$ of the filament, as determined by fast camera visible light imaging. Models of the major air constituents' ionization rate $W_{i}$ vs. local laser intensity $I$, and of temperature $T$ and mean axial electron momentum $\left\langle p_{{z}}\right\rangle $ vs. peak laser intensity $I_{0}$ are then used to infer a hypothetical steady state filament's $I_{0}$, $T$, major species particle densities, and assumed axially invariant current time integral $Q$ and current decay rate $\nu$ after pulse passage. $Q$ is independently measured via the filament's self-emission signal in the waveguide

arXiv:2605.08947v2 Announce Type: replace Abstract: This paper introduces a low-cost experimental mockup to simulate the laser cutting process of containers in nuclear decommissioning. It is composed of a three-axis table supporting a cuboid container with ultraviolet-sensitive faces, a six-degree-of-freedom serial manipulator holding an ultraviolet torch that simulates the laser, and a visual system based on cameras and fiducial markers. The system employs a constrained task-space adaptive motion controller that compensates for inaccurate parameters and eliminates the need to calibrate the system. Furthermore, as the motion controller explicitly accounts for geometric constraints, the robot reactively avoids collisions with obstacles while handling the ultraviolet torch. To improve the tracking of the laser-cutting path, we control the ultraviolet beam, which requires only four degrees of freedom, instead of the full end-effector pose. Experiments show that, despite an initially

arXiv:2607.09229v1 Announce Type: new Abstract: Laser-driven proton acceleration from nanostructured solid targets has been extensively studied, yet its performance under realistic temporal contrast conditions at petawatt-class facilities remains an open question. We present an experimental investigation of proton generation from nanostructured and flat solid targets performed at the ELI-NP facility using femtosecond laser pulses at peak intensities of $\sim 3\times10^{21}$ \wcm. Proton spectra are compared for two contrast regimes: $\sim 10^{-10}$ without plasma mirror and $\sim 10^{-13}$ with single plasma mirror. Importantly, measurable enhancement in the cutoff energy persists for the nanowire targets at both contrast levels, indicating robustness of nanowire targets against moderate pre-pulse intensities. Alongside, study of energy resolved angular distribution reveals that nanowires promote more directional emission with higher flux of high-energy protons along the target

arXiv:2607.09220v1 Announce Type: new Abstract: A non-intrusive optical diagnostic based on Laser-Induced Fluorescence (LIF) is developed for measuring salt mass fraction in highly concentrated aqueous solutions relevant to absorption heat pump applications. The method relies on a systematic redshift of the fluorescence emission spectra of several dyes, likely induced by an increase of ionic strength with salt mass fraction. A two-color ratiometric approach, based on the ratio of fluorescence intensities in two spectral bands, enables robust mass fraction measurements. This study demonstrates that the techniques is not limited to LiBr but also NaCl, relevant for desalination applications. In parallel, fluorescence lifetime measurements using Time-Correlated Single Photon Counting (TCSPC) reveals that fluorescence lifetime is also affected by the LiBr mass fraction, allowing an alternative measurement technique. For both techniques, many dyes are tested and are compared in terms of

As the adoption of electric vehicles continues to grow, so does the need for the safe and permanent storage of battery materials and industrial chemical waste. Certain waste streams require disposal in what are known as Category IV landfills, which impose particularly stringent requirements on storage containers. These must simultaneously ensure environmental protection, safe handling and long-term structural integrity.

Sequential 1550-nm fractional focal point technology followed by pulsed dye laser is safe and effective for reducing resistant port-wine birthmarks, a new study suggests.

arXiv:2607.08680v1 Announce Type: new Abstract: Magnetic fields generated by the Rayleigh-Taylor instability were measured in laser-accelerated planar foils using ultrafast proton radiography. Thin plastic foils were irradiated with $\sim$4-kJ, 2.5-ns laser pulses focused to an intensity of $\sim$10$^{14}$ W$/$cm$^{2}$ on the OMEGA EP Laser System. Target modulations were seeded by laser nonuniformities and amplified during target acceleration by the Rayleigh-Taylor instability. The experimental data show the hydrodynamic evolution of the target and MG-level magnetic fields generated in the broken foil. The experimental data are in good agreement with predictions from 2-D magnetohydrodynamic simulations.

arXiv:2607.08229v1 Announce Type: new Abstract: Maintaining carbon steel in marine environments requires surface treatments capable of simultaneously removing corrosion products and chloride contaminants whilst modifying the residual oxide layer. In this study, salt-contaminated SS400 carbon steel was treated using a Q-switched pulsed fibre laser characterized by a full width at half maximum (FWHM) of approximately 150 ns and a decaying tail extending to about 600 ns. The pulse energy was fixed at 1 mJ, and the repetition frequency was varied between 50 and 200 kHz to investigate the effects of cumulative thermal accumulation. Under 100 W (100 kHz) conditions, WDS-EPMA analysis confirmed that Na and Cl levels dropped to near-background values, demonstrating the comprehensive removal of sea-salt-derived contaminants. SEM observations revealed the transition of the porous rust layer into a dense, laser-modified layer, whilst XPS analysis confirmed the suppression of the $\text{Fe}^{3+}$

arXiv:2607.07965v1 Announce Type: new Abstract: We introduce a multimodal directed energy deposition (DED) dataset for predicting the probabilistic local geometric variation of single laser tracks produced on stainless-steel 316L substrates. The dataset supports the NSF Future Manufacturing Data Challenge and contains three complementary modalities: in-situ thermal image sequences from a Stratonics ThermaViz melt-pool sensor, scanning electron microscopy (SEM) images acquired using a Zeiss EVO MA10 system, and full-field height maps acquired using a Bruker ContourGT-K white-light 3D optical profilometer. Each experiment is a bead-on-plate scan at one of four laser powers, 200, 300, 350, and 400 W, with a fixed scan speed of 10 mm/s. The release includes starter notebooks, participant-facing code, and a multimodal coordinate convention that links thermal, SEM, and height-map measurements over a common physical 20-100 mm window.

arXiv:2607.07125v1 Announce Type: new Abstract: Exotic helium atoms act as unique atomic traps for heavy, negatively charged particles, protecting them from nuclear annihilation and nuclear capture on timescales long enough to enable high-precision laser spectroscopy. Such measurements serve as stringent tests of three-body quantum electrodynamics and offer a direct route to determining fundamental particle masses. Motivated by upcoming spectroscopic efforts targeting pionic ($\pi^{-\,4}\mathrm{He}^+$) and kaonic ($K^{-\,4}\mathrm{He}^+$) helium, we present a rigorous theoretical evaluation of the collisional and density effects governing these systems. Using an ab initio potential energy surface and coupled-channel quantum scattering calculations, we study the collisional stability of the candidate metastable states against inelastic quenching in a cryogenic helium buffer gas. Furthermore, we provide theoretical reference values for the pressure broadening and pressure shift

arXiv:2607.07005v1 Announce Type: new Abstract: Efficient terahertz (THz) generation with high field amplitude and pulse energy is studied through the interaction of a single-color long-wavelength infrared (LWIR) laser pulse with gaseous targets. Particle-In-Cell (PIC) simulations are performed to investigate the underlying mechanism and analyze the properties of the emitted THz radiation. The results reveal that THz pulses are generated via photon deceleration of the LWIR laser, driven by enhanced electron density accumulation at the pulse front in the self-modulated wakefield regime. The influence of key parameters, including target density, laser intensity, and propagation length, on nonlinear laser modulation and the resulting THz generation efficiency is analyzed. Important scalings governing the laser-to-THz energy conversion efficiency are identified from PIC simulations and validated through theoretical analysis. The study demonstrates a laser-to-THz energy conversion

arXiv:2607.06965v1 Announce Type: new Abstract: Magnetic fields generated by the Rayleigh-Taylor instability were measured in laser-accelerated planar foils using ultrafast proton radiography. Thin plastic foils were irradiated with $\sim$4-kJ, 2.5-ns laser pulses focused to an intensity of $\sim$10$^{14}$ W$/$cm$^{2}$ on the OMEGA EP Laser System. Target modulations were seeded by laser nonuniformities and amplified during target acceleration by the Rayleigh-Taylor instability. The experimental data show the hydrodynamic evolution of the target and MG-level magnetic fields generated in the broken foil. The experimental data are in good agreement with predictions from 2-D magnetohydrodynamic simulations.

arXiv:2607.06961v1 Announce Type: new Abstract: Stimulated Brillouin scattering (SBS) microscopy enables label-free mapping of local viscoelastic properties, but frequency-domain implementations are often limited by uncertainty in the pump-probe frequency-difference axis. We demonstrate an RF-defined single-laser electro-optic-modulation SBS microscope in which the pump and probe are derived from the same optical carrier and their frequency difference is set by an electro-optically generated sideband. This architecture makes laser-frequency noise largely common mode and eliminates optical wavelength tuning during spectral scanning. It achieves Brillouin frequency shift and linewidth precisions of 0.07 MHz and 0.30 MHz, respectively. Comparison with a low-NA reference linewidth indicates a system-level spectral broadening of approximately 3.1 MHz, corresponding to an effective spectral resolution of approximately 3 MHz. Imaging of femtosecond-laser-modified chalcogenide glass resolves

arXiv:2607.06946v1 Announce Type: new Abstract: Magnetic fields generated by a current flowing through a U-shaped coil connecting two copper foils were measured using ultrafast proton radiography. Two $\sim$1.25 kJ, 1-ns laser pulses propagated through laser entrance holes in the front foil, and were focused to the back foil with an intensity of $\sim$3 $\times$ 10$^{16}$ W$/$cm$^{2}$. The intense laser-solid interaction induced a high voltage between the copper foils and generated a large current in the connecting coil. The proton data show $\sim$40-50 Tesla magnetic fields at the center of the coil $\sim$3-4 ns after laser irradiation. The experiments provide significant insight for future target designs that aim to develop a powerful source of external magnetic fields for various applications in high-energy-density science.

arXiv:2607.05746v1 Announce Type: new Abstract: Using 20 OMEGA laser beams at the Laboratory for Laser Energetics, University of Rochester, to irradiate a flat plastic target in a hollow ring configuration, we created supersonic cylindrical stable plasma jets with self-generated megagauss magnetic fields extending out to > 4 mm. These well-collimated magnetized jets possess a number of distinct and novel properties that will allow us to study the dynamics, physical processes and scaling properties of astrophysical jets not feasible with other laboratory settings. The dimensionless parameters of these laboratory jets fall in the same regime as those of YSO jets. They will also provide new versatile laser-based platforms to study magnetized shocks, shear flows and other plasma processes under controllable conditions.

Controlling light within microscopic spaces is crucial for next-generation optical devices such as photonic integrated circuits and localized sensors. Microspheres formed of luminescent π-conjugated polymers act as optical resonators that confine and amplify light via whispering gallery modes (WGMs), and they are promising candidates for microscale organic lasers and photonic applications. However, conventional microsphere resonators are geometrically isotropic and emit isotropic light, making directional control of emissions challenging.

CO2 laser-based sign shops have become one of the more viable small manufacturing businesses available to makers and

arXiv:2607.04994v1 Announce Type: new Abstract: The interaction of ultraintense lasers with magnetized overdense plasmas reveals a fundamentally new regime of laser-driven particle acceleration. Particle-in-cell simulations demonstrate the generation of directional, quasi-monoenergetic electrons in the MeV energy range superimposed on a broad thermal electron background with the estimated acceleration gradient of 3.6 MeV/{\mu}m, which is the highest till date. In contrast to conventional laser-plasma accelerators, which rely on underdense plasmas and are therefore constrained to relatively low plasma densities and limited beam charge, the present scheme operates in plasmas with densities orders of magnitude higher, opening new possibilities for the generation of high-flux energetic electron beams. A central result of this work is the demonstration of the excitation of electron Bernstein waves during relativistic laser interaction with magnetized overdense plasmas. The subsequent

arXiv:2607.04966v1 Announce Type: new Abstract: Laser cooled and trapped atoms have been the workhorse of atomic physics for the past four decades. The predominant method has been the highly versatile Magneto-Optical Trap. We describe an alternative laser trap involving a simple geometry of collimated laser beams that provides both a velocity and position dependent restoring force such that a dense cloud of cold atoms is formed. This technique produces similar atom number ($>10^6$) and density ($10^{10}$\,atoms/cm$^{3}$) to the Magneto-Optical Trap, albeit with \emph{no magnetic field}. The beam geometry is compatible with conventional sub-Doppler cooling techniques, allowing the trapped cloud to be cooled to $

arXiv:2607.04646v1 Announce Type: new Abstract: We construct a non-Hermitian Dirac-vortex model that combines a complex-mass winding with an infinite-imaginary-potential boundary, extending the Jackiw-Rossi and neutrino-billiard models to the dissipative regime. Moreover, this model serves as a minimal theory for the recently proposed topological-cavity surfaceemitting laser (TCSEL): the imaginary mass encodes vertical radiation loss and the absorbing boundary defines the active region. We derive closed-form expressions for the modal frequencies, thresholds, and tunable vectorbeam polarizations, which are validated experimentally. Our work provides a rare example in which an analytical non-Hermitian topological theory captures the essential physics for engineering practical optoelectronic devices.

arXiv:2607.04229v1 Announce Type: new Abstract: The optical emission in laser-induced breakdown spectroscopy (LIBS) is governed by the spatial intensity distribution of the incident laser beam, which influences plasma formation and evolution. Beam shaping therefore offers a route to control plasma dynamics and emission yield; however, its effects in LIBS remain insufficiently quantified, particularly under conditions relevant to compact instrumentation. In this work, a diffractive optical element (DOE) is used to transform a Gaussian beam into a 2x2 array, producing simultaneously expanding, co-propagating ablation plumes that interact during expansion. Plasma evolution from Cu and Si targets is investigated in vacuum using a Nd:YAG laser (1064 nm, 5 ns, 10 J/cm2), combining time-resolved imaging with optical emission spectroscopy. The multi-spot configuration results in enhanced emission intensity compared to single-spot irradiation, with increases of ~9 for Si and ~3 for Cu. The

arXiv:2607.02902v1 Announce Type: new Abstract: Micro-ring lasers (MRLs) are attractive light sources for energy-efficient optical interconnects, but their intrinsic directional bistability leads to unpredictable clockwise/counter-clockwise emission. We demonstrate stable unidirectional emission in hybrid quantum-dot (QD) III-V/Si MRLs using passive reflective feedback integrated on the bus waveguide, leaving the ring cavity unperturbed. Three reflector architectures - Y-splitter loop mirrors, adiabatic Y-splitter loop mirrors, and distributed Bragg reflectors (DBRs) - are benchmarked against a reflector-free bidirectional baseline through combined experiment and coupled-mode-theory rate-equation modeling. All designs preserve ultra-low thresholds of 0.79-1.12 mA (112-158 A/cm^2, roughly an order of magnitude below prior quantum-well unidirectional ring lasers) while enhancing single-facet output power and wall-plug efficiency, with directional isolation up to 27.65 dB for the DBR.

arXiv:2607.02863v1 Announce Type: new Abstract: The fluctuation -- dissipation theorem (FDT) is shown to provide a powerful resource for the analysis of stimulated light scattering from laser-driven density gratings, including stimulated Brillouin scattering and its kinetic-regime extension. In the physical setting of stimulated light scattering by density gratings, the FDT establishes that the dynamics of disturbances induced in a medium by a laser-driven electrostrictive force unfolds via the same physical pathways as the dynamics of internal, spontaneous fluctuations in this medium at equilibrium. When integrated into a suitable kinetic framework, the FDT leads to a significant simplification of the analysis of stimulated light scattering, allowing the stimulated gain/loss spectrum to be found directly from the spectrum of spontaneous density fluctuations without the need to solve kinetic equations with an external-field term. Operating within this framework, we derive a physically

Fraunhofer ILT in Aachen has developed a highly complex laser-optical system for a quantum computer currently under construction at the 5th Institute of Physics at the University of Stuttgart. This system enables 2,000 Rydberg atoms to be positioned with submicrometer precision in the computer's highly compact vacuum chamber. To do this, the system projects an array of 2,000 individually controllable laser beams into the chamber. These beams act as optical tweezers and hold the trapped Rydberg atoms precisely at the distance required for them to interact with each other. The computer's quantum logic processes are based on these interactions.

arXiv:2607.01796v1 Announce Type: cross Abstract: Coherence-based spectroscopy methods are powerful tools to explore structure and dynamics of matter. However, towards higher photon energies, the generation of sequences of pulses with well-characterized relative delays and phases remains a challenge. Here, we introduce a method to measure the relative phase $\varphi$ between subsequent transform-limited pulses from high-repetition-rate x-ray free-electron lasers (XFELs). It is based on a Ramsey-type interference measurement, enabled by introducing long-lived M\"ossbauer resonances into the XFEL beam path up- or downstream a primary experiment, which allow one to bridge the temporal gap between the XFEL pulses. The measured phase can be used as additional input for the analysis of the primary experiment.

arXiv:2607.02040v1 Announce Type: new Abstract: This paper presents a four-channel prototype system for the geometric combining and coherent addition of tightly focused femtosecond laser radiation into a standing-wave field configuration. A stabilization system for beam pointing and relative phase of the four optical channels has been implemented, and its performance has been experimentally demonstrated. To characterize the standing-wave electromagnetic field distribution at the main focus of the system, an original measurement technique based on a fiber subwavelength optical probe has been employed. This work has been conducted in support of the exawatt-scale XCELS project.

arXiv:2607.01406v1 Announce Type: new Abstract: We present a laser system referenced to a room-temperature ultrastable cavity employing crystalline AlGaAs coatings. We demonstrate a fractional frequency instability of $4.2 \times 10^{-17}$, which is one of the lowest for room temperature systems and surpasses the limit imposed by Brownian noise if dielectric coatings were employed. For the first time in a room temperature system we identified the spontaneous fluctuations of the coating birefringence as a leading contribution to frequency instability. At optimized conditions we achieve an ultrastable cavity with an eigenfrequency that is highly immune to power fluctuations. As acceleration noise is the main noise contribution, we demonstrated that a feed-forward method can reduce the influence of accelerations on the cavity-stabilized laser frequency by a factor of four.

arXiv:2607.01707v1 Announce Type: new Abstract: Large vision-language models (LVLMs) exhibit strong reasoning ability but suffer from visual forgetting during long-horizon decoding, where attention progressively drifts away from visual evidence. Existing methods largely treat this issue as a late-stage attention decay problem or attempt to mitigate it through heuristic reminders or post-hoc attention lifting. Through systematic empirical analysis, we find that performance degradation under visual forgetting is largely driven by two overlooked factors: early-stage attention decay disrupts evidence acquisition, and attention concentration on a subset of task-irrelevant visual sink tokens. Motivated by these insights, we propose LASER, a post-training framework that regulates both the visual attention trajectory and intra-visual token attention distribution during reasoning. Technically, LASER introduces two complementary rewards: a Visual Grounding Reward, which encourages the model to

arXiv:2606.32019v1 Announce Type: new Abstract: We report the first demonstration of a laser-atomic oscillator with cesium (Cs) atoms. A laser-atomic oscillator (LAO) is analogous to an active mode-locked laser with a self-excited modulator, i.e. atoms, at a ground-state hyperfine transition frequency. Therefore, a LAO can be configured as the simplest active atomic clock or a self-oscillating, earth-field atomic magnetometer that delivers oscillation signals both optically and electrically. With the current experimental Cs-LAO setup, when it is configured as an atomic clock using the 0--0 hyperfine transition, the short-term fractional frequency instability is around 10$^{-10}$ level. When it is configured as a self-oscillating magnetometer using a magnetically-sensitive hyperfine transition, the magnetic field sensitivity is around 100 fT/$\sqrt{\rm{Hz}}$ at 60 Hz. The presented Cs-LAO uses a cavity length from $\sim6.5$ cm to $\sim11.4$ cm. Ultimately, the minimal length of a

arXiv:2606.30873v1 Announce Type: new Abstract: In this paper, using a simplified model of the xenon atom, we numerically study the possibilities of efficient generation of coherent pulses in the XUV range through the resonant interaction of atoms with a moderate-intensity laser field, leading to the generation of its harmonics. We demonstrate the interplay of two systems of resonances affecting the harmonic generation efficiency. One is the channel-closing resonances, which arise when the sum of ionization and ponderomotive energies is equal to the energy of an integer number of laser photons. The second is the bound-bound transition resonances corresponding to an integer number of photons with a total energy equal to the energy gap between the Stark-shifted ground and excited states. The harmonic yields in the range of laser parameter values where both resonances occur exhibit a peculiar behavior, namely, near the intersection point of the resonances, a pronounced dip is observed,

arXiv:2606.31580v1 Announce Type: new Abstract: Large reasoning models (LRMs) such as DeepSeek-R1 have achieved strong performance through extended chain-of-thought (CoT) generation. However, deploying them on edge devices raises a conflict between long CoT sequences and constrained resources. Recent confidence-based early exit methods reduce CoT length for individual requests, yet they apply fixed thresholds from a single-request perspective, ignoring multi-request concurrency and load fluctuation in edge serving. To bridge this gap, we propose \underline{L}oad-\underline{A}ware \underline{S}erving with \underline{E}arly-exit for \underline{R}easoning (LASER). LASER couples two complementary designs: (1) a load-aware adaptive exit threshold that adjusts the confidence bar based on real-time system load within an empirically validated robust range, and (2) a difficulty- and load-aware reasoning budget pre-allocation that assigns compute resources by request difficulty and system

Israel has announced a space laser weapons project, claiming no other nation has such a capability Read Full Article at RT.com

arXiv:2606.29255v1 Announce Type: new Abstract: Online inspection images of final optics in high-power laser facilities contain pseudo-damage sites that closely resemble true damage sites. Determining the authenticity of online-detected sites is therefore difficult and requires accurate matching to offline ground-truth sites. However, this matching remains highly challenging due to limited match-discriminative features, local geometric distortions, and numerous distractor sites. Existing matching models mainly suppress distractors implicitly through loss-function supervision. We propose a confidence-feedback-weighted graph matching network that requires only damage-site centroid coordinates as input. It estimates node matchability confidence from each round of matching scores and feeds it back as a reliability weight to guide subsequent edge-feature aggregation, thereby suppressing distractor propagation and enhancing cross-graph discriminability. Within this framework, a geometric

arXiv:2606.29383v1 Announce Type: new Abstract: This report presents experimental measurements of coupling efficiency and laser-induced damage thresholds for a polarization-maintaining (PM) fiber patchcord with integrated end caps, evaluated at 532 nm using a compact actively Q-switched DPSS laser with sub-nanosecond pulses. It also describes the development of a custom free-space coupling array through which the problem of low coupling efficiency was identified and successfully addressed. No instantaneous damage was observed at peak power densities exceeding 10 GW/cm$^2$. Sustained operation at 30 kHz was maintained over extended durations (>5 h) at peak power densities of ~13 GW/cm$^2$, while prolonged 1 kHz operation led to gradual degradation at peak power densities of ~24 GW/cm$^2$. The broader context of this work is the investigation of stimulated Raman scattering (SRS) in optical fibers for nonlinear frequency conversion. This process requires the efficient delivery of

arXiv:2606.29214v1 Announce Type: new Abstract: We propose a method to detect quantum stochastic effects in radiation reaction by irradiating a V-shaped plasma cavity with an ultra-intense laser pulse. The pulse accelerates GeV electrons along the inner surface and simultaneously drives strong-field surface wave near the cavity apex. The accelerated electron bunches then collide with the surface wave, the latter acts as an effective counter-propagating ultra-intense electromagnetic wave, triggering significant radiation reaction. Importantly, because the surface wave is confined to an ultra-thin QED plasma layer (on the scale of the skin depth) where the expected number of hard photon emissions per electron is of order unity, stochastic effects are expected. Three-dimensional particle-in-cell simulations with different QED models show that radiation reaction strongly reshapes the angular distribution of high-energy electrons. In particular, electrons deflected by the surface wave

arXiv:2606.29096v1 Announce Type: new Abstract: This work is a generalization of our previous study [arXiv:2406.17944], which dealt with the coherent and incoherent combination of linearly polarized Gaussian laser beams operating in continuous-wave mode under a $2\pi$ focusing configuration. In the present work, the laser beams are focused within a solid angle that can reach $4\pi$ by using two opposing source planes, where all the lasers from both planes are focused onto the same point in the focal plane. Our results show that the focal spot area obtained with either one or two source planes remains unchanged, despite the fact that, in the two-source-plane configuration, the numerical aperture (NA) of the system is twice that of the $2\pi$ focusing scheme. However, the intensity at the focal point is four times greater than that obtained with a single source plane. In addition, the longitudinal resolution is significantly improved, yielding a focal volume smaller than $0.5 \lambda^3$

When a high-intensity laser interacts with plasma, the charged particles typically oscillate back and forth like waves on the ocean. But what if the laser itself could twist like a whirlpool? Researchers have now demonstrated a rotating, spring-shaped laser pulse, opening new possibilities for fusion energy, particle acceleration, astrophysics and beyond.

A research team led by Prof. Zhang Zhirong from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has developed a high-performance laser-based three-dimensional methane gas cloud imaging telemetry system that enabled visualization of microleakages, accurate location of leakage sources and quantitative retrieval of emission rates.

Controlling and trapping molecules, units of a substance consisting of two or more chemically bound atoms, with laser light is significantly more challenging than trapping individual atoms. This is because molecules exhibit more complex vibrational and rotational dynamics that make them more difficult to cool and trap.

arXiv:2606.26271v1 Announce Type: new Abstract: Linear $\mathcal{PT}$-symmetric dimer necklaces use cyclic coupling to organize phase-locked modes, while class-B laser--resonator dimers use carrier inversion to destabilize gain--loss dynamics and produce routes to chaos. We study a cyclic necklace of class-B laser--resonator dimers to determine how inter-dimer coupling and cyclic phase constraints modify carrier-mediated instabilities. The carrier inversion turns the necklace into an amplitude--phase--carrier system whose active-site gain controls intensities, while the linewidth-enhancement factor shifts phases. We derive the real dynamical equations, identify uniform fixed points above threshold, and classify their phase configurations under cyclic closure. Even necklaces support full synchronization, a uniform $\pi$ shift, and two alternating phase configurations; odd necklaces support only the first two. Linear stability of these configurations partitions the coupling plane into

arXiv:2606.26260v1 Announce Type: new Abstract: In laser penetration welding, the assessment of penetration state and weld seam morphology plays a crucial role in determining the weld quality. This paper presents a comprehensive introduction of the innovative muti-task deep learning model that has the capability to predict penetration state, depth, and weld seam morphology with high accuracy. The monitoring platform relies on weld pool images captured during the laser welding process using a complementary metal-oxide-semiconductor camera. The proposed model integrates spatiotemporal features extracted from top weld pool images along with welding parameters, establishing a deep learning framework based on convolutional neural networks and state space models for more efficient extraction and processing of spatial-temporal information. Furthermore, a reliable method for constructing the dataset is proposed to enhance both robustness and generalization capability of the developed model.

In an international experiment, researchers observed Jahn–Teller polarons—quasiparticles that could play an important role in future ultrafast spintronic devices. These polarons emerged within the crystal lattice of cobalt oxide that had been activated by carefully tailored laser pulses.

arXiv:2606.25267v1 Announce Type: cross Abstract: Rapid and robust laser-frequency auto-locking is essential for the field deployment of quantum communications, quantum computing, and precision-measurement technologies; however, achieving this remains a considerable challenge. Here, we propose and demonstrate an auto-locking scheme employing Bayesian optimization and discrete biorthogonal wavelet transformation. First, the reference is rapidly sought by making intelligent use of historical observations, eliminating the inherent blindness of the traditional parameter-scanning method. Second, the frequency reference is robustly identified by pinpointing transition signals with the discrete biorthogonal wavelet transformation and analyzing their immutable frequency differences and relative magnitudes, which are determined by the inherent atomic structure and remain resistant to environmental disturbances. This proposed approach achieves a fivefold acceleration in reference searching

arXiv:2606.26054v1 Announce Type: new Abstract: Our direct-drive-relevant experiments on the low-coherence Kunwu laser facility identify two-plasmon decay (TPD) as the primary source of hot electrons, and demonstrate for the first time that broadband laser pulses enhance TPD. Using particle-in-cell simulations, we attribute this TPD enhancement and the consequent hot electron production to stochastic intensity spikes inherent in broadband laser fields, robust in both weakly- and strongly-driven regimes. These findings suggest that mitigating hot electron generation requires suppressing these intensity spikes.

arXiv:2606.25046v1 Announce Type: new Abstract: We experimentally investigate the potential of $BaMgF_4$ crystals to create a continuous-wave (CW) solid state laser at the vacuum ultraviolet (VUV) wavelength of 148.4 nm via cavity-enhanced second harmonic generation. This investigation is motivated by the development of a nuclear optical clock based on a transition between the ground and isomeric state in the $^{229}Th$ nucleus. For this purpose, a $BaMgF_4$ crystal was grown, optically polished and periodically poled. The crystal was inserted into a power-enhancement cavity, resonant at the fundamental wavelength of 296.8 nm and the generated laser light at 148.4 nm was characterized. Within this proof-of-concept investigation, a VUV output power of typically ($16\pm1$) pW is obtained. This marks the first time that this type of crystal is used to generate VUV laser light. The experimental findings are compared to theoretical expectations and provide a clear path for future

arXiv:2606.26078v1 Announce Type: new Abstract: Supervised deep learning has been widely used for weld penetration state classification; however, its performance often degrades significantly under domain shift, such as when transferring models between welding processes with distinct physical mechanisms:for instance, from arc-dominated tungsten inert gas (TIG) welding to keyhole-based laser welding. To overcome this limitation, we propose an unsupervised domain adaptation (UDA) framework integrated with a gradual source domain expansion (GSDE) strategy. Evaluated on dedicated TIG and laser welding datasets, our approach achieves high accuracy in both same-process and cross-process transfer tasks. Specifically, it attains average accuracies of 90.65% on TIGFH and 90.72% on LSPS in same-process settings, surpassing a supervised baseline by 35.83% and 38.87%, respectively. More notably, in cross-process scenarios, it reaches 80.48% for TIG to Laser and 81.13% for Laser to TIG, improving

arXiv:2606.26059v1 Announce Type: new Abstract: The laser welding full-penetration is of critical importance, as it constitutes one of the fundamental factors in achieving defect-free welded joints. Accurate prediction of the penetration state is therefore essential for ensuring weld quality. To this end, this paper introduces SimPhysNet, a novel algorithm that achieves high classification accuracy in laser welding penetration prediction using only a limited number of labelled images. This approach effectively overcomes the limitations of supervised learning classification algorithms, which are hindered in industrial applications by their dependence on extensive, high-quality labelled data. The core of SimPhysNet is a unique self-supervised learning paradigm that embeds physical priors into a contrastive learning framework. By incorporating a physics-informed neural network (PINN), the model is guided to extract physically meaningful features of the molten pool and keyhole from a

Deep inside gas giants like Jupiter and Saturn, hydrogen and helium coexist under pressures millions of times greater than Earth's atmosphere. Under those conditions, helium may separate from hydrogen and influence a planet's internal heat flow, structure and magnetic field. Understanding these processes and how these materials behave under extreme conditions is essential to building accurate models of planetary evolution.

Scientists at NPL have demonstrated the best-reported laser frequency stability achieved with an optical reference cavity operating at room temperature, marking a major advance in ultrastable laser technology. The team's results have been published in Optica.

arXiv:2606.23719v1 Announce Type: cross Abstract: Laser powder bed fusion (LPBF) is a promising additive manufacturing technique that suffers from quality assurance concerns. Predicting melt pools from process parameters is crucial for assessing quality prior to manufacturing but remains a difficult problem because of the complex physical processes underlying LPBF. Quantum computers present a new computing paradigm, providing a new approach to information processing using quantum entanglement and superposition. This paper presents a practical demonstration of a hybrid quantum-classical model that leverages quantum computing to improve process parameter feature extraction with a quantum feature encoder. To make the quantum approach computationally feasible for large datasets, we first employ a clustering algorithm to reduce the number of expensive quantum computations. These quantum features are then processed by a classical neural network to predict the melt pool morphology, allowing

arXiv:2606.23851v1 Announce Type: new Abstract: This work investigates the implementation of artificial intelligence and machine learning (AI/ML) for real-time monitoring in laser powder bed fusion (LPBF) additive manufacturing. We developed a binary image classification framework for distinguishing normal and abnormal melt pool images using a balanced dataset of 1,200 images collected from Nickel superalloy 625 on the NIST AMMT platform. The study evaluates accuracy and inference time based on control requirements and hardware limitations of open-architecture LPBF machines. We benchmark three transfer learning architectures (ResNet50, EfficientNetB0, and MobileNetV2) against two Random Forest approaches: one trained on EfficientNetB0 feature embeddings (hybrid) and one trained on raw pixel features (baseline). Images are stratified into 80/20 train-test splits, with a further 90/10 validation split on the training set, and undergo standardized resizing, normalization, and

arXiv:2606.23602v1 Announce Type: cross Abstract: Powder x-ray diffraction (PXRD) under laser-driven dynamic compression is a powerful tool to investigate material response to extreme pressure, temperature and strain rates. Robust PXRD platforms have been developed at kJ and MJ laser facilities worldwide including the Powder X-Ray Diffraction Image Plate (PXRDIP) at the Omega Laser Facility at the Laboratory for Laser Energetics (LLE) and the TARget Diffraction In Situ (TARDIS) at the National Ignition Facility (NIF). Here we present further developments of data analysis methods focused towards improving the fidelity of the PXRD intensity determination for these platforms. We illustrate these methods by discussing how they can be implemented in a data analysis package and applied to shock compression data on diamond near 1 TPa. We discuss using the XRD signal from the collimating pinhole or a layer of un-compressed material in the sample package as \textit{ in-situ} references for XRD

arXiv:2606.21675v1 Announce Type: cross Abstract: We investigate the intensity stability of the superradiant laser. Our study focuses on the architecture where a continuous beam of atoms in an electronically excited state crosses the mode of a high-finesse Fabry-Perot cavity, which has been proposed as a new architecture of an active optical clock. We show that such superradiant laser can become unstable and develop chaotic behavior. We derive an analytical criterion for this instability and find that it may only occur when the lifetime of photons in the cavity is significantly shorter than the lifetime of atoms. This criterion allows for refining the necessary parameters to run a superradiant laser as a frequency reference in the optical domain. In particular, we point-out the consequences of the instability on intensity fluctuations and laser linewidth. On the other hand, we also point out that the superradiant laser, when in the unstable regime, can become an interesting playground

arXiv:2606.21068v1 Announce Type: cross Abstract: The phonon laser realized in a trapped ion, i.e., a self-sustained mechanical oscillator, has demonstrated the unique characteristics in practically detecting externally applied electric signals without the prerequisite of sideband cooling. Entering the quantum regime via sideband cooling is expected to further improve its sensing performance. Here we report the first experimental realization of a quantum-regime single-ion phonon laser ($\bar{n}

arXiv:2606.23396v1 Announce Type: new Abstract: X-ray free-electron lasers (XFELs) enable diffraction-before-destruction measurements of individual nanosized bioparticles, making it possible to study the structure and dynamics of non-crystalline targets under near-biologically relevant conditions. In this work, we employ rotational invariants for model-guided and ab initio three-dimensional (3D) structure determination of aerosolized bacteriophages PR772 measured with an XFEL. The rotational invariants derived from diffraction patterns collected during multiple independent XFEL experiments facilitate the characterization of similarities and structural variations within the measured ensembles of PR772 particles. Despite modest experimental resolution, we can identify various structural features of the viruses, including the asymmetric nature of capsid distortions from the perfect icosahedral shape, density variations in the encapsulated content, and an extension at one of the capsid

arXiv:2606.22523v1 Announce Type: new Abstract: Hybrid bright-dark soliton complexes offer profound insights into multi-component nonlinear wave dynamics, yet their systematic generation via artificial saturable absorbers remains unexplored. Here, we experimentally demonstrate a comprehensive hierarchy of higher-order hybrid soliton architectures within a single nonlinear polarization rotation (NPR)-based erbium-doped fiber laser. Continuous tuning of intracavity polarization states and pump power enables reproducible access to soliton structures, with stable mode-locking confirmed at 8 MHz and a signal-to-noise ratio exceeding 72 dB. Cross-phase modulation (XPM)-mediated inter-component coupling and birefringence-induced polarization evolution collectively govern the observed soliton multiplicity, with NPR's inherent tunability proving decisive in accessing higher-order hybrid soliton regimes unexplored in prior studies. These findings expand the fundamental taxonomy of dissipative

arXiv:2606.21526v1 Announce Type: new Abstract: Resonant photoionization in the intense high-frequency regime can exhibit extremely asymmetric Autler-Townes doublets whose origin remains debated. It has been attributed either to interference between perturbative ionization pathways or to a non-perturbative dressing of the continuum. Here we show that these interpretations arise from a common effective Hamiltonian framework, in which dressed-state stabilization is governed by the coherent interplay of resonant and nonresonant pathways. We demonstrate that further simplification, using the strong-field approximation, obscures this mechanism. In contrast, our time-dependent essential-state model, where electrons are rigorously coupled to the continuum, achieves excellent agreement with ab initio simulations of the time-dependent Schr\"odinger equation for helium.

arXiv:2606.21274v1 Announce Type: new Abstract: Precise pointing control is a critical requirement for interspacecraft laser interferometry, as angular misalignment introduces measurement noise and even leads to laser link loss. We present a nested control architecture that uses differential wavefront sensing signals to drive a fast steering mirror (FSM) to track the incoming beam, while feeding the FSM's angular changes back to the attitude and orbit control system (AOCS) to suppress angle-dependent optical path variations. This scheme is experimentally validated in our hexapod-based setup. Relative to standalone FSM actuation, the nested configuration enhanced pointing stability by 6.9 dB and 4.9 dB in the horizontal and vertical directions across the frequency band from 3 mHz to the AOCS actuation's unity-gain frequency. Additionally, tilt-to-length coupling was suppressed by an order of magnitude below 6 mHz and by two orders of magnitude below 0.45 mHz. These results demonstrate

Researchers have demonstrated a new way to make spatially separated lasers synchronize and act as a single coherent light source—without extreme conditions or complex materials.

Manufacturing has never stood still. From the invention of the assembly line to the rise of computer-controlled machinery,

arXiv:2606.19556v1 Announce Type: new Abstract: Predictive simulation of melt pool dynamics in laser-based processing of metals, e.g., laser beam welding or laser powder bed fusion additive manufacturing, requires accurate resolution of thermo-hydrodynamic interactions at the melt-gas interface. Here, evaporation-induced recoil pressure and temperature-dependent surface tension govern the flow. Because these mechanisms depend sensitively, often exponentially, on the interface temperature, reliable predictions demand highly accurate heat transfer models. Popular diffuse-interface formulations smear the extreme thermal gradients as typical for laser-metal interactions, leading to interface temperature errors that critically degrade the accuracy of interface force predictions and melt pool dynamics. We present a hybrid sharp-diffuse interface approach for high-fidelity modelling of melt pool thermo-hydrodynamics with rapid evaporation. The heat transfer problem is represented using a

arXiv:2606.20298v1 Announce Type: new Abstract: Laser wakefield accelerators (LWFAs) provide extremely large accelerating gradients for compact electron accelerators and photon sources but are limited by dephasing, where trapped electrons outrun the accelerating phase of the wakefield. Flying-focus pulses can eliminate dephasing by driving a wake at the vacuum speed of light, but these pulses involve tradeoffs such as varying spot size, long duration, or large plasma volume. Here we show that a spatiotemporally structured laser pulse propagating in a plasma waveguide can drive a wakefield at the vacuum speed of light while maintaining a constant spot size and ultrashort duration. The pulse is formed by superposing plasma-waveguide modes with appropriately selected frequencies. Compared with flying-focus approaches, the waveguide substantially reduces the required plasma volume. Scaling laws and quasi-3D particle-in-cell simulations show that the single-stage energy gain increases

arXiv:2606.20149v1 Announce Type: new Abstract: Laser-driven lightsails have emerged as a promising route for accelerating ultralight spacecraft to high speeds using beamed optical energy. Realizing this concept pushes the limits of light-matter interaction, materials science, structural engineering, and nanomechanical design. A central challenge is to create nanophotonic reflectors that combine ultralow mass, large illuminated area, and survival under high optical power densities. No previous experiment has combined these constraints in a single structure sufficient to produce measurable radiation-pressure displacement. Here, we report the largest subwavelength tethered lightsails to date: nanoscale-thickness, millimeter-wide silicon nitride membranes patterned with billions of holes. Despite their subwavelength thickness, they achieve 99% reflection through resonant photonic modes, combining ultralow areal density with high reflectivity. Their compliance enables radiation-pressure

arXiv:2606.19768v1 Announce Type: new Abstract: Diode-pumped solid-state (DPSS) lasers play a central role in modern photonics owing to their exceptional efficiency and ability to extend spectral coverage beyond the reach of semiconductor diodes. These attributes have enabled breakthroughs in precision metrology, quantum optics, and coherent communications. However, bringing the proven advantages of DPSS gain media such as Nd:YAG onto an integrated photonic platform has remained difficult, largely due to inefficient pump utilization and limited power-scaling in chip-scale implementations. Here, we demonstrate the first photonic-integrated Nd:YAG laser-amplifier system that overcomes these challenges with a micro-chip based master-oscillator-power-amplifier (\mu-MOPA) architecture. The seed laser, employing a double-resonant microring resonator, could reach a threshold as low as 2.9 \mu W. The single-pass waveguide amplifier, when optimized separately, provides up to 46.6 dB

arXiv:2606.19484v1 Announce Type: new Abstract: Coherent vacuum-ultraviolet (VUV) lasers are indispensable for precision measurement, quantum optics, and materials science. Recent high-resolution spectroscopy of the Th-229 nuclear clock transition near 148 nm highlights the urgent demand for intense, narrow-linewidth VUV lasers for advancing metrology and testing fundamental physics. However, existing VUV generation schemes typically require enhancement cavities [C. Zhang et al., Opt. Lett. 47, 5591-5594 (2022)], atomic resonances [Q. Xiao et al., Nature 650, 852-856 (2026)], or random quasi-phase-matched nonlinear crystals [V. Lal et al., Optica 12, 1971-1974 (2025)]. Here, we demonstrate a VUV frequency comb via cascaded frequency doubling of a 2400 nm Cr:ZnS comb to its 16th harmonic in nonlinear crystals. The final stage employs a bulk-grown, spatially uniform quasi-phase matched (QPM) crystal developed by IPG, combining VUV transparency, high $\chi^2$ nonlinearity, and power

Experiments at Lawrence Livermore National Laboratory's National Ignition Facility (NIF) require breathtaking precision. Each of the 192 lasers is focused to a width of a few millimeters to enter a 3-millimeter hole at the top or bottom of a 2-centimeter (0.8-inch) gold canister known as a hohlraum.

How does light turn into motion within a metal? A team of researchers from European XFEL, the University of Potsdam and other participating institutions has shown that ultrashort optical laser pulses can trigger extremely rapid lattice vibrations in periodically layered metal structures—not primarily by heating the atomic lattice, but through the pressure exerted by hot electrons. The results are published in Nature Communications.

arXiv:2606.18845v1 Announce Type: new Abstract: We review beam-quality physics in laser-driven (LWFA) and beam-driven (PWFA) plasma wakefield accelerators through the symmetry group of the idealised blowout wake -- axisymmetry $\mathrm{SO}(2)_\phi$, adiabatic longitudinal translation, and propagation-direction parity. Transverse perturbations of the wake are classified by an integer azimuthal multipole order $m$ labelling the irreducible representations of $\mathrm{SO}(2)_\phi$, with the lowest beam-quality observables coupling at a specific multipole: the bunch centroid at $m=1$, cross-plane emittance coupling at $m=2$. A symplectic analogy relates transverse matching to longitudinal beam loading. Several phenomena common to LWFA and PWFA -- hose instabilities, pulse-front-tilt jitter, spot-asymmetry emittance growth, polarisation-dependent centroid motion, resonant cross-plane mixing -- populate the two lowest non-trivial $m$-channels and admit a unified discussion. The

arXiv:2606.19265v1 Announce Type: new Abstract: Continuum robots offer a promising approach for minimally invasive and natural-orifice surgical procedures due to their inherent compliance and dexterity. However, this flexibility also makes estimating the current shape of the robot challenging. Several approaches have been used to reconstruct the shape of these robots, including imaging, optical sensing, magnetic sensing, and resistive sensing. Strain sensors fabricated using direct laser writing (DLW) could provide an alternative sensing method. This technique involves using a laser to induce carbonization of certain polymers to create graphene patterns, such as strain sensors. In this paper, we demonstrate how a flexible continuum joint and a DLW sensor can be machined as one monolithic structure using the same laser and the same setup. The fabricated sensors are characterized using linear and nonlinear models, which are used to predict the joint angle with error as low as 1.76

arXiv:2606.17988v1 Announce Type: new Abstract: The strong electric fields from tightly-focused and ultrashort laser beams have always been discussed as a way to accelerate charged particles without any need for a medium or external cavity. Radially-polarized light is one way to do this, motivated by the emergence of longitudinal electrical fields with tight focusing. However, the laser pulse will generally quickly overtake the electrons under its influence, and every-other half-cycle will decelerate the electrons in effect partially reversing the acceleration. In this work we present the effect of optical aberrations, primarily spherical aberration, and how despite their purely spatial nature they can significantly optimize the net acceleration, and advantageously allow for longer pulses to drive this optical field-based process. We discuss the optical physics responsible for this increase in performance and find optimal aberration profiles using a stochastic algorithm.

arXiv:2606.17635v1 Announce Type: new Abstract: A quantum-enhanced approach for fast temperature diagnostics in ultrashort laser surface processing is introduced. The goal is to overcome limitations of existing methods, such as plasma emission, emissivity changes during ablation, and the need for time-consuming pump-probe measurements. The proposed method exploits polarization anisotropy in entangled photon pairs. The idler photon interacts with the laser-affected material surface, while its entangled counterpart is detected in a remote optical arm. Temperature-dependent changes in the complex refractive index modify the reflectance of p- and s-polarizations on the idler path, altering the coincidence-resolved polarization statistics of the signal photons. Using a Qiskit-based model incorporating experimental pump-probe reflectometry data, remote reconstruction of rapid thermal dynamics during femtosecond laser ablation is demonstrated. Although based on simulation, the model employs

Ultrafast laser pulses switch a quantum material from insulating to conductive, revealing a hidden phase with potential for future electronics.

One of the hardest things to calculate for an asteroid is its mass—but it is such a critical feature. It determines how much of an impact it would have if it hits something, or how many resources are potentially available on it. But to accurately measure it, we typically use optical sensing and a guesstimate of its density based on its spectral profile.

arXiv:2606.16066v1 Announce Type: new Abstract: It has been known for decades that laser fusion can be, and often is plagued by the production of energetic electrons.produced either by a instability or by the production of energetic electrons, produced either by an instability or by the energetic tail of a Maxwellian distribution. Despite more than 25 years of a variety of efforts, there is still no generally accepted way to address this issue. This work hopes to advance the progress by developing a Fokker Planck model which is simple enough to be used at every time step of a rad-hydro simulation, and accurate enough to be useful. It makes several approximations, the main one being that the percentage of these energetic electrons is small. Recent experiments confirm this so far that this is the case for plasmas subject to a laser plasma instability. Hence energetic electons interact with the background plasma, but not with each other. This work makes no attempt to solve for the entire

arXiv:2606.15687v1 Announce Type: new Abstract: Splitting an ultrashort drive pulse into a weak leading pulse and a strong main pulse is known to raise the energy of protons accelerated by the target-normal-sheath-acceleration (TNSA) mechanism, because the leading pulseforms a preplasma that increases the absorption of the main pulse. The allocation of energy between the two pulses and their temporal separation are coupled control parameters, and under a fixed total energy they have not been optimized jointly in a systematic way. We address this problem with two-dimensional particle-in-cell simulations driven by Bayesian optimization. Treating the prepulse energy fraction $r$ and the interpulse delay $\Delta t$ as free parameters under a fixed total energy, a campaign of 32 simulations, of which 16 are Sobol-initialized and 16 adaptively selected, locates an optimum at $r\approx0.07$ and $\Delta t\approx234$~fs. The proton cutoff energy increases from 7.7~MeV for the single pulse to

What would it take to instantly transform a material from an electrical insulator into a conductive state without ever touching it? Using ultrafast laser pulses and powerful X-rays, scientists at the National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science user facility at DOE's Brookhaven National Laboratory—developed a methodology to generate "hidden" phases and understand why they work.

arXiv:2606.14300v1 Announce Type: new Abstract: Helium nanodroplets provide a unique and versatile platform for investigating strong-field-driven nanoplasma dynamics. In this work, we present large-scale, GPU-accelerated particle-in-cell simulations using \textsc{PIConGPU} to study the interaction of pure helium nanodroplets containing up to $10^{6}$ atoms with intense near-infrared femtosecond laser pulses, and compare the results with single-shot velocity-map electron imaging and ion measurements. The simulations describe the plasma evolution from the first ionization events to collective electron motion, nanoplasma formation, and early expansion. We show that the calculated electron and ion observables reproduce the main features of the measured spectra in systems with similar cluster sizes and laser intensities. Our results demonstrate that \textsc{PIConGPU} captures the essential physics of nanoplasma formation previously addressed mainly with molecular-dynamics or TDDFT

arXiv:2606.13183v1 Announce Type: new Abstract: Experimental results aimed at demonstrating the feasibility of a two-section delay mask for the generation of ultrashort pulse trains are reported. Based on the initial simulation results, a 500 um thick circular fused silica plate featuring a central aperture was designed to enable two distinct transverse portions of the incident laser pulse to be focused, ideally, with equal intensity. This fulfills one of the requirements of the resonant multipulse ionization injection (ReMPI) scheme for laser wakefield acceleration. The experiment was carried out at the CNR-INO Intense Laser Irradiation Laboratory using a 240 TW laser system operated at 120 TW, as part of the ongoing preparation for the first experimental demonstration of ReMPI.

Installed in a custom Titan Krios, the laser phase plate boosts small‑protein cryo‑EM by enhancing motion correction, early‑frame recovery, particle visualization, and 3D classification and alignment. The post Laser‑Driven Phase Contrast Enhances Cryo‑EM Resolution of Small Proteins appeared first on GEN - Genetic Engineering and Biotechnology News.

In a landmark achievement in biological imaging, researchers at the University of California, Berkeley and Biohub today announced the successful demonstration of the laser phase plate, a novel device that dramatically improves the contrast of images produced by cryo-electron microscopes, opening up an entirely new view of human biology.

arXiv:2606.12041v1 Announce Type: cross Abstract: The orbital angular momentum of light is an intriguing property for developing light driven applications. It emerged as an independent degree of freedom by which to manipulate light and, consequently, the interaction of light with matter. Several methods exist for the generation of light carrying orbital angular momentum, mostly employing transmitting or reflecting optical components, which radially modulate the phase profile of the light. As one of such components, transmissive q-plates established themselves as standard elements due to their usability over a broad wavelength range. Here, we present our approach to build a highly reflective q-plate based on a plasmonic metasurface capable of converting orbital angular momentum from the nanostructure to ultrashort laser pulses without temporal broadening. We highlight its working principle over a wide range of wavelengths for reflection under normal and gracing incidence.

arXiv:2606.12323v1 Announce Type: new Abstract: We realize two-dimensional magnetically-assisted Sisyphus laser cooling of an asymmetric top molecule (ATM), calcium monoamide (CaNH$_2$). Vibrational state closure is achieved with $41.1 \pm 6.3$ photons scatters using optical pumping of the $X[3_1]$ state. Photon-cycling measurements show good agreement with branching ratios determined by dispersed fluorescence spectroscopy. Rotational closure is maintained by driving the $X[1_{11}] \to A [0_{00}]$ transition. The observed absence of additional state leakage channels broadens the scope of molecular laser cooling to include ATMs, which are the most general geometric class of molecules and possess the richest internal structure. Future applications of quantum controlled ATMs include new quantum information platforms and searches for physics beyond the Standard Model.

arXiv:2606.12308v1 Announce Type: new Abstract: Laser-induced forward transfer (LIFT) is a nozzle-free laser-assisted printing method that provides an advanced manufacturing route for spatially selective deposition of functional inks, nanoparticle suspensions, polymers, hydrogels, biological materials, and other difficult-to-nozzle formulations. The apparent simplicity of LIFT, however, conceals a strongly coupled laser-liquid interaction. Laser energy is absorbed within a confined donor architecture, converted into thermal and plasma responses, and then transformed into bubble-mediated motion of the donor material. The cavitation bubble provides the transient mechanical bridge between optical energy deposition and the hydrodynamic ejection process. This chapter presents LIFT from a multiscale perspective centered on bubble dynamics and material ejection. It first reviews major LIFT donor architectures. Then, it examines how donor ribbon design, absorbing-layer properties, laser

arXiv:2606.11395v1 Announce Type: new Abstract: High damage threshold gratings are in demand worldwide as critical components for next generation ultrahigh intensity lasers. Here we investigate the pulse-duration dependence of ultrafast laser-induced damage thresholds (LIDT) in hybrid multilayer dielectric gratings, touted to combine superior performance properties of both metallic and multilayer dielectric (MLD) gratings, using a dynamic finite-difference time-domain model incorporated with linear and non-linear absorption models. Simulations agree with reported experimental LIDT values for three representative designs and predict scaling exponents which vary with pulse durations ranging from 10 to 500 fs. The results reveal strong dependence on both material bandgap and grating field distribution, providing guidance for designing high LIDT gratings.