On behalf of all at High Power Laser Science and Engineering we would like to congratulate the team at Lawrence Livermore National Laboratory (LLNL) on de
On behalf of all at High Power Laser Science and Engineering we would like to congratulate the team at Lawrence Livermore National Laboratory (LLNL) on demonstrating fusion ignition at the National Ignition Facility. This major scientific achievement was realized on the 5 December 2022 at the LLNL and announced at a press briefing on the 13 December 2022 by the United States Department of Energy’s National Nuclear Security Administration. This was a historic milestone and the culmination of decades of effort.show less
The laser-damage performance of optics is known to be negatively affected by microscale particle contamination induced by the operational environment. Thi
The laser-damage performance of optics is known to be negatively affected by microscale particle contamination induced by the operational environment. This work investigates the properties of particles accumulating in various locations near critical optics inside the OMEGA EP grating compressor chamber during quarterly operational periods over a 2-year duration. The particles found were characterized using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The analysis indicates significant concentrations of micrometer- to nanometer-scale particles inside the vacuum chamber, with higher values observed near the port leading to the OMEGA EP target chamber. The distribution of the chemical composition of these particles varies between collection periods. Although understanding of the mechanisms of particle generation and transport remains uncertain, the hypothesis is that this particle load represents a risk for contaminating the surfaces of high-value optics located inside the chamber, including the compression gratings and deformable mirrors, and therefore affecting their laser-damage resistance and overall operational lifetime.show less
Attosecond soft X-ray pulses are of great importance for the study of ultrafast electronic phenomena. In this paper, a feasible method is proposed to gene
Attosecond soft X-ray pulses are of great importance for the study of ultrafast electronic phenomena. In this paper, a feasible method is proposed to generate isolated fully coherent attosecond soft X-ray free electron laser via optical frequency beating. Two optical lasers with the opposite frequency chirps are used to induce a gradient frequency energy modulation, which helps to generate a gradually varied spacing electron pulse train. Subsequently, the undulator sections with electron beam delay lines are used to amplify the target ultra-short radiation. Numerical start-to-end simulations have been performed and the results demonstrate that an isolated soft X-ray pulse with the peak power of 330 GW and pulse duration of 620 as can be achieved by the proposed technique.show less
Presented is a novel way to combine snapshot compressive imaging and lateral shearing interferometry in order to capture the spatio-spectral phase of an u
Presented is a novel way to combine snapshot compressive imaging and lateral shearing interferometry in order to capture the spatio-spectral phase of an ultrashort laser pulse in a single shot. A deep unrolling algorithm is utilized for snapshot compressive imaging reconstruction due to its parameter efficiency and superior speed relative to other methods, potentially allowing for online reconstruction. The algorithm’s regularization term is represented using a neural network with 3D convolutional layers to exploit the spatio-spectral correlations that exist in laser wavefronts. Compressed sensing is not typically applied to modulated signals, but we demonstrate its success here. Furthermore, we train a neural network to predict the wavefronts from a lateral shearing interferogram in terms of Zernike polynomials, which again increases the speed of our technique without sacrificing fidelity. This method is supported with simulation-based results. While applied to the example of lateral shearing interferometry, the methods presented here are generally applicable to a wide range of signals, including Shack–Hartmann-type sensors. The results may be of interest beyond the context of laser wavefront characterization, including within quantitative phase imaging.show less
This paper reviews the recent biomedical detection developments of scanning near-field optical microscopy (SNOM), focusing on scattering-type SNOM (s-SNOM), atomic force microscope-based infrare
This paper reviews the recent biomedical detection developments of scanning near-field optical microscopy (SNOM), focusing on scattering-type SNOM (s-SNOM), atomic force microscope-based infrared spectroscopy (AFM-IR), peak force infrared microscopy (PFIR), and photo-induced force microscopy (PiFM), which have the advantages of label-free, non-invasive and specific spectral recognition. Considering the high-water content of biological samples and the strong absorption of water by infrared waves, we divide the relevant researches of these techniques into two categories, one based on non-liquid environment and the other based on liquid environment. In the non-liquid environment, the chemical composition and structure information of biomedical samples can be obtained with nanometer resolution. In the liquid environment, these techniques can be used to monitor the dynamic chemical reaction process and track the process of chemical composition and structure change of single molecules, which are conducive to exploring the development mechanism of physiological processes. We elaborate their experimental challenges, technical means and actual cases for three micro biomedical samples (including biomacromolecules, cells and tissues). Their development prospect and the challenges are also discussed. This work lays a foundation for the rational design and efficient use of near-field optical microscopy to explore the characteristics of microscopic biology.show less
The optical angular momentum is ubiquitous to the science of light, especially whenever the polarization state and the spatial distribution of the phase are involved, which are most often associ
The optical angular momentum is ubiquitous to the science of light, especially whenever the polarization state and the spatial distribution of the phase are involved, which are most often associated with the spin and orbital parts of the total angular momentum, respectively. Noteworthy, these two contributions to the total optical angular momentum have been originally introduced in the framework of a mechanical detection framework involving a torsion pendulum. Today, the classical and quantum mechanical aspects of spin and orbital angular momentum of light, and their mutual coupling, remain active research topics offering exciting perspectives for photonic technologies. This brief historical overview shows how the torsion pendulum has accompanied scientific progress on mechanical effects based on the angular degrees of freedom of light since Beth's pioneering contribution published in 1935 [Phys. Rev. {\bf 48}, 471 (1935)].show less
This study analyzes the linewidth narrowing characteristics of free-space-running BLs and investigates the approaches to achieve linewidth compression and power enhancement simultaneously. The r
This study analyzes the linewidth narrowing characteristics of free-space-running BLs and investigates the approaches to achieve linewidth compression and power enhancement simultaneously. The results show that the Stokes linewidth behavior in a free-space-running BL cavity is determined by the phase diffusion of the pump and the technical noise of the system. Experimentally, a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%, which is nearly 2.5 times compressed compared to the linewidth of the pump (7.36 kHz). In addition, the theorical analysis shows that at a pump power of 60 W and a coupling mirror reflectivity of 96%, a Stokes output with a linewidth of 1.6 kHz and up to 80% optical conversion efficiency can be achieved by reducing the insertion loss of the intracavity. This study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.show less
The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than was possible using the prior generation. Facilities requiring human interv
The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than was possible using the prior generation. Facilities requiring human intervention between laser repetitions need to adapt in order to keep pace with the new laser technology. A distributed networked control system can enable laboratory-wide automation and feedback control loops. These higher-repetition-rate experiments will create enormous quantities of data. A consistent approach to managing data can increase data accessibility, reduce repetitive data-software development, and mitigate poorly organized metadata. An opportunity arises to share knowledge of improvements to control and data infrastructure currently being undertaken. We compare platforms and approaches to state-of-the-art control systems and data management at high-power laser facilities, and we illustrate these topics with case studies from our community.show less