All Publications


  • Compact high repetition rate Thomson parabola ion spectrometer REVIEW OF SCIENTIFIC INSTRUMENTS Nedbailo, R., Park, J., Hollinger, R., Wang, S., Mariscal, D., Morrison, J., Song, H., Zeraouli, G., Scott, G. G., Ma, T., Rocca, J. J. 2023; 94 (2): 023505

    Abstract

    We present the development of a compact Thomson parabola ion spectrometer capable of characterizing the energy spectra of various ion species of multi-MeV ion beams from >1020W/cm2 laser produced plasmas at rates commensurate with the highest available from any of the current and near-future PW-class laser facilities. This diagnostic makes use of a polyvinyl toluene based fast plastic scintillator (EJ-260), and the emitted light is collected using an optical imaging system coupled to a thermoelectrically cooled scientific complementary metal-oxide-semiconductor camera. This offers a robust solution for data acquisition at a high repetition rate, while avoiding the added complications and nonlinearities of micro-channel plate based systems. Different ion energy ranges can be probed using a modular magnet setup, a variable electric field, and a varying drift-distance. We have demonstrated operation and data collection with this system at up to 0.2 Hz from plasmas created by irradiating a solid target, limited only by the targeting system. With the appropriate software, on-the-fly ion spectral analysis will be possible, enabling real-time experimental control at multi-Hz repetition rates.

    View details for DOI 10.1063/5.0101859

    View details for Web of Science ID 000933169800003

    View details for PubMedID 36859067

  • A flexible proton beam imaging energy spectrometer (PROBIES) for high repetition rate or single-shot high energy density (HED) experiments (invited) REVIEW OF SCIENTIFIC INSTRUMENTS Mariscal, D. A., Djordjevic, B. Z., Anirudh, R., Bremer, T., Campbell, P. C., Feister, S., Folsom, E., Grace, E. S., Hollinger, R., Jacobs, S. A., Kailkhura, B., Kalantar, D., Kemp, A. J., Kim, J., Kur, E., Liu, S., Ludwig, J., Morrison, J., Nedbailo, R., Ose, N., Park, J., Rocca, J. J., Scott, G. G., Simpson, R. A., Song, H., Spears, B., Sullivan, B., Swanson, K. K., Thiagarajan, J., Wang, S., Williams, G. J., Wilks, S. C., Wyatt, M., Van Essen, B., Zacharias, R., Zeraouli, G., Zhang, J., Ma, T. 2023; 94 (2): 023507

    Abstract

    The PROBIES diagnostic is a new, highly flexible, imaging and energy spectrometer designed for laser-accelerated protons. The diagnostic can detect low-mode spatial variations in the proton beam profile while resolving multiple energies on a single detector or more. When a radiochromic film stack is employed for "single-shot mode," the energy resolution of the stack can be greatly increased while reducing the need for large numbers of films; for example, a recently deployed version allowed for 180 unique energy measurements spanning ∼3 to 75 MeV with <0.4 MeV resolution using just 20 films vs 180 for a comparable traditional film and filter stack. When utilized with a scintillator, the diagnostic can be run in high-rep-rate (>Hz rate) mode to recover nine proton energy bins. We also demonstrate a deep learning-based method to analyze data from synthetic PROBIES images with greater than 95% accuracy on sub-millisecond timescales and retrained with experimental data to analyze real-world images on sub-millisecond time-scales with comparable accuracy.

    View details for DOI 10.1063/5.0101845

    View details for Web of Science ID 000958687800002

    View details for PubMedID 36859040

  • Ablating Ion Velocity Distributions in Short-Pulse-Heated Solids via X-Ray Doppler Shifts PHYSICAL REVIEW LETTERS Kraus, B. F., Gao, L., Fox, W., Hill, K. W., Bitter, M., Efthimion, P. C., Moreau, A., Hollinger, R., Wang, S., Song, H., Rocca, J. J. 2022; 129 (23): 235001

    Abstract

    Solids ablate under laser irradiation, but experiments have not previously characterized the initiation of this process at ultrarelativistic laser intensities. We present first measurements of bulk ion velocity distributions as ablation begins, captured as a function of depth via Doppler-shifted x-ray line emission from two viewing angles. Bayesian analysis indicates that bulk ions are either nearly stationary or flowing outward at the plasma sound speed. The measurements quantitatively constrain the laser-plasma ablation mechanism, suggesting that a steplike electrostatic potential structure drives solid disassembly.

    View details for DOI 10.1103/PhysRevLett.129.235001

    View details for Web of Science ID 000918851200002

    View details for PubMedID 36563203

  • Ultra-compact x-ray spectrometer for high-repetition-rate laser-plasma experiments REVIEW OF SCIENTIFIC INSTRUMENTS Zeraouli, G., Mariscal, D., Grace, E., Scott, G. G., Swanson, K. K., Simpson, R., Djordjevic, B. Z., Nedbailo, R., Song, H., Morrison, J., Park, J., Hollinger, R., Wang, S., Rocca, J. J., Ma, T. 2022; 93 (11)

    View details for DOI 10.1063/5.0100970

    View details for Web of Science ID 000880313600009

  • Investigation of Proton Beam-Driven Fusion Reactions Generated by an Ultra-Short Petawatt-Scale Laser Pulse LASER AND PARTICLE BEAMS Schollmeier, M. S., Shirvanyan, V., Capper, C., Steinke, S., Higginson, A., Hollinger, R., Morrison, J. T., Nedbailo, R., Song, H., Wang, S., Rocca, J. J., Korn, G. 2022; 2022
  • Applications of machine learning to a compact magnetic spectrometer for high repetition rate, laser-driven particle acceleration REVIEW OF SCIENTIFIC INSTRUMENTS Swanson, K. K., Mariscal, D. A., Djordjevic, B. Z., Zeraouli, G., Scott, G. G., Hollinger, R., Wang, S., Song, H., Sullivan, B., Nedbailo, R., Rocca, J. J., Ma, T. 2022; 93 (10): 103547

    Abstract

    Accurately and rapidly diagnosing laser-plasma interactions is often difficult due to the time-intensive nature of the analysis and will only become more so with the rise of high repetition rate lasers and the desire to implement feedback on a commensurate timescale. Diagnostic analysis employing machine learning techniques can help address this problem while maintaining a high degree of accuracy. We report on the application of machine learning to the analysis of a scintillator-based electron spectrometer for experiments on high intensity, laser-plasma interactions at the Colorado State University Advanced Lasers and Extreme Photonics facility. Our approach utilizes a neural network trained on synthetic data and tested on experiments to extract the accelerated electron temperature. By leveraging transfer learning, we demonstrate an improvement in the neural network accuracy, decreasing the network error by 50%.

    View details for DOI 10.1063/5.0101857

    View details for Web of Science ID 000878198400001

    View details for PubMedID 36319355

  • Streaked sub-ps-resolution x-ray line shapes and implications for solid-density plasma dynamics (invited) REVIEW OF SCIENTIFIC INSTRUMENTS Kraus, B. F., Gao, L., Hill, K. W., Bitter, M., Efthimion, P. C., Hollinger, R., Wang, S., Song, H., Nedbailo, R., Rocca, J. J., Mancini, R. C., Beatty, C. B., MacDonald, M. J., Shepherd, R. 2022; 93 (10): 103527

    Abstract

    A high-resolution x-ray spectrometer was coupled with an ultrafast x-ray streak camera to produce time-resolved line shape spectra measured from hot, solid-density plasmas. A Bragg crystal was placed near laser-produced plasma to maximize throughput; alignment tolerances were established by ray tracing. The streak camera produced single-shot, time-resolved spectra, heavily sloped due to photon time-of-flight differences, with sufficient reproducibility to accumulate photon statistics. The images are time-calibrated by the slope of streaked spectra and dewarped to generate spectra emitted at different times defined at the source. The streaked spectra demonstrate the evolution of spectral shoulders and other features on ps timescales, showing the feasibility of plasma parameter measurements on the rapid timescales necessary to study high-energy-density plasmas.

    View details for DOI 10.1063/5.0101853

    View details for Web of Science ID 000885758100003

    View details for PubMedID 36319349

  • Homogeneous, Micron-Scale High-Energy-Density Matter Generated by Relativistic Laser-Solid Interactions PHYSICAL REVIEW LETTERS Beier, N. F., Allison, H., Efthimion, P., Flippo, K. A., Gao, L., Hansen, S. B., Hill, K., Hollinger, R., Logantha, M., Musthafa, Y., Nedbailo, R., Senthilkumaran, V., Shepherd, R., Shlyaptsev, V. N., Song, H., Wang, S., Dollar, F., Rocca, J. J., Hussein, A. E. 2022; 129 (13): 135001

    Abstract

    Short-pulse, laser-solid interactions provide a unique platform for studying complex high-energy-density matter. We present the first demonstration of solid-density, micron-scale keV plasmas uniformly heated by a high-contrast, 400 nm wavelength laser at intensities up to 2×10^{21}  W/cm^{2}. High-resolution spectral analysis of x-ray emission reveals uniform heating up to 3.0 keV over 1  μm depths. Particle-in-cell simulations indicate the production of a uniformly heated keV plasma to depths of 2  μm. The significant bulk heating and presence of highly ionized ions deep within the target are attributed to the few MeV hot electrons that become trapped and undergo refluxing within the target sheath fields. These conditions enabled the differentiation of atomic physics models of ionization potential depression in high-energy-density environments.

    View details for DOI 10.1103/PhysRevLett.129.135001

    View details for Web of Science ID 000861755700006

    View details for PubMedID 36206410

  • Multi-GeV Electron Bunches from an All-Optical Laser Wakefield Accelerator PHYSICAL REVIEW X Miao, B., Shrock, J. E., Feder, L., Hollinger, R. C., Morrison, J., Nedbailo, R., Picksley, A., Song, H., Wang, S., Rocca, J. J., Milchberg, H. M. 2022; 12 (3)
  • High-repetition-rate, multi-MeV deuteron acceleration from converging heavy water microjets at laser intensities of 10(21) W/cm(2) APPLIED PHYSICS LETTERS Treffert, F., Curry, C. B., Chou, H. J., Crissman, C. J., DePonte, D. P., Fiuza, F., Glenn, G. D., Hollinger, R. C., Nedbailo, R., Park, J., Schoenwaelder, C., Song, H., Wang, S., Rocca, J. J., Roth, M., Glenzer, S. H., Gauthier, M. 2022; 121 (7)

    View details for DOI 10.1063/5.0098973

    View details for Web of Science ID 000861138400019

  • Vacuum laser acceleration of super-ponderomotive electrons using relativistic transparency injection. Nature communications Singh, P. K., Li, F. Y., Huang, C. K., Moreau, A., Hollinger, R., Junghans, A., Favalli, A., Calvi, C., Wang, S., Wang, Y., Song, H., Rocca, J. J., Reinovsky, R. E., Palaniyappan, S. 2022; 13 (1): 54

    Abstract

    Intense lasers can accelerate electrons to very high energy over a short distance. Such compact accelerators have several potential applications including fast ignition, high energy physics, and radiography. Among the various schemes of laser-based electron acceleration, vacuum laser acceleration has the merits of super-high acceleration gradient and great simplicity. Yet its realization has been difficult because injecting free electrons into the fast-oscillating laser field is not trivial. Here we demonstrate free-electron injection and subsequent vacuum laser acceleration of electrons up to 20 MeV using the relativistic transparency effect. When a high-contrast intense laser drives a thin solid foil, electrons from the dense opaque plasma are first accelerated to near-light speed by the standing laser wave in front of the solid foil and subsequently injected into the transmitted laser field as the opaque plasma becomes relativistically transparent. It is possible to further optimize the electron injection/acceleration by manipulating the laser polarization, incident angle, and temporal pulse shaping. Our result also sheds light on the fundamental relativistic transparency process, crucial for producing secondary particle and light sources.

    View details for DOI 10.1038/s41467-021-27691-w

    View details for PubMedID 35013209

    View details for PubMedCentralID PMC8749006

  • Solid-Density Ion Temperature from Redshifted and Double-Peaked Stark Line Shapes PHYSICAL REVIEW LETTERS Kraus, B. F., Gao, L., Hill, K. W., Bitter, M., Efthimion, P. C., Gomez, T. A., Moreau, A., Hollinger, R., Wang, S., Song, H., Rocca, J. J., Mancini, R. C. 2021; 127 (20): 205001

    Abstract

    Heβ spectral line shapes are important for diagnosing temperature and density in many dense plasmas. This work presents Heβ line shapes measured with high spectral resolution from solid-density plasmas with minimized gradients. The line shapes show hallmark features of Stark broadening, including quantifiable redshifts and double-peaked structure with a significant dip between the peaks; these features are compared to models through a Markov chain Monte Carlo framework. Line shape theory using the dipole approximation can fit the width and peak separation of measured line shapes, but it cannot resolve an ambiguity between electron density n_{e} and ion temperature T_{i}, since both parameters influence the strength of quasistatic ion microfields. Here a line shape model employing a full Coulomb interaction for the electron broadening computes self-consistent line widths and redshifts through the monopole term; redshifts have different dependence on plasma parameters and thus resolve the n_{e}-T_{i} ambiguity. The measured line shapes indicate densities that are 80-100% of solid, identifying a regime of highly ionized but well-tamped plasma. This analysis also provides the first strong evidence that dense ions and electrons are not in thermal equilibrium, despite equilibration times much shorter than the duration of x-ray emission; cooler ions may arise from nonclassical thermalization rates or anomalous energy transport. The experimental platform and diagnostic technique constitute a promising new approach for studying ion-electron equilibration in dense plasmas.

    View details for DOI 10.1103/PhysRevLett.127.205001

    View details for Web of Science ID 000719865300006

    View details for PubMedID 34860067

  • Design of flexible proton beam imaging energy spectrometers (PROBIES) PLASMA PHYSICS AND CONTROLLED FUSION Mariscal, D. A., Djordjevic, B. Z., Grace, E. S., Hollinger, R., Ma, T., Scott, G. G., Song, H., Simpson, R. A., Rocca, J. J., Wang, S. 2021; 63 (11)
  • Comparing plasma conditions in short-pulse-heated foils via fine-structure x-ray emission REVIEW OF SCIENTIFIC INSTRUMENTS Kraus, B. F., Chien, A., Gao, L., Hill, K. W., Bitter, M., Efthimion, P. C., Chen, H., Schneider, M. B., Moreau, A., Hollinger, R., Wang, S., Song, H., Rocca, J. J. 2021; 92 (3): 033525

    Abstract

    Fine-structure x-ray spectra have been measured from foils with embedded tracer layers at two laser facilities. A suite of layered foils with thin Ti tracers under varied tamper layers was studied at both the Titan and the ALEPH 400 nm laser facilities, where Ti Heα emission was recorded using a high-resolution Bragg crystal spectrometer. Several indicators of plasma parameters are examined in the spectra, including temperature- and density-dependent line ratios and line broadening from Stark and opacity effects. Spectra indicate that (1) the plasma density at ALEPH is significantly higher than at Titan and (2) the electron temperature is high for near-surface layers at both facilities but drops more quickly with depth at ALEPH. These inferences of plasma conditions are consistent with differing levels of temporal contrast at each laser facility.

    View details for DOI 10.1063/5.0043524

    View details for Web of Science ID 000627451500002

    View details for PubMedID 33820090

  • Single-shot picosecond resolution Fourier transform holographic microscopy with large field of view using a compact soft X-ray laser Wang, S., Rockwood, A., Wang, Y., Chao, W., Naulleau, P., Song, H., Menoni, C., Marconi, M., Rocca, J. J., Bleiner, D. SPIE-INT SOC OPTICAL ENGINEERING. 2021

    View details for DOI 10.1117/12.2594832

    View details for Web of Science ID 000759193300023

  • Single-shot large field of view Fourier transform holography with a picosecond plasma-based soft X-ray laser OPTICS EXPRESS Wang, S., Rockwood, A., Wang, Y., Chao, W., Naulleau, P., Song, H., Menoni, C. S., Marconi, M., Rocca, J. J. 2020; 28 (24): 35898-35909

    Abstract

    It is challenging to obtain nanoscale resolution images in a single ultrafast shot because a large number of photons, greater than 1011, are required in a single pulse of the illuminating source. We demonstrate single-shot high resolution Fourier transform holography over a broad 7 µm diameter field of view with ∼ 5 ps temporal resolution. The experiment used a plasma-based soft X-ray laser operating at 18.9 nm wavelength with nearly full spatial coherence and close to diffraction-limited divergence implemented utilizing a dual-plasma amplifier scheme. A Fresnel zone plate with a central aperture is used to efficiently generate the object and reference beams. Rapid numerical reconstruction by a 2D Fourier transform allows for real-time imaging. A half-pitch spatial resolution of 62 nm was obtained. This single-shot nanoscale-resolution imaging technique will allow for real-time ultrafast imaging of dynamic phenomena in compact setups.

    View details for DOI 10.1364/OE.409815

    View details for Web of Science ID 000592953200041

    View details for PubMedID 33379696

  • Extreme ionization of heavy atoms in solid-density plasmas by relativistic second-harmonic laser pulses NATURE PHOTONICS Hollinger, R., Wang, S., Wang, Y., Moreau, A., Capeluto, M. G., Song, H., Rockwood, A., Bayarsaikhan, E., Kaymak, Pukhov, A., Shlyaptsev, V. N., Rocca, J. J. 2020; 14 (10): 607-+
  • Femtosecond Chirped-Pulse Amplifier System Based on Spectrum Control and Dispersion Optimization CHINESE JOURNAL OF LASERS-ZHONGGUO JIGUANG Niu Jia, Liu Bowen, Song Huanyu, Zhao Sicong, Li Shaobei, Wang Tienan, Gu Xinhua, Chai Lu, Hu Minglie 2020; 47 (1)
  • High-pulse-quality Yb-fiber amplifier generation of 10 mu J, 250 fs pulses at 500 kHz repetition rate OPTIK Niu, J., Liu, B., Song, H., Zhao, S., Li, S., Gu, X., Hu, M. 2020; 200
  • Strain compensated robust semiconductor saturable absorber mirror for fiber lasers CHINESE OPTICS LETTERS Wang, Y., Lin, N., Gao, W., Song, H., Hu, M., Li, H., Bao, W., Ma, X., Zhang, Z. 2019; 17 (7)
  • Research Status and Development Trend of High Power Femtosecond Fiber Laser Amplifiers CHINESE JOURNAL OF LASERS-ZHONGGUO JIGUANG Yan Dongyu, Liu Bowen, Song Huanyu, Li Yuan, Chu Yuxi, Chai Lu, Hu Minglie, Wang Chingyue 2019; 46 (5)
  • Hybrid femtosecond laser system based on a Yb:KGW regenerative amplifier for N-P polarization CHINESE OPTICS LETTERS Yan, D., Liu, B., Chu, Y., Song, H., Chai, L., Hu, M., Wang, C. 2019; 17 (4)
  • 1.1 mu m Femtosecond Laser Pulses Generation From 1.06 mu m Self-Seeded Picosecond Coherent Raman Fiber Amplification and Frequency Shift JOURNAL OF LIGHTWAVE TECHNOLOGY Chen, W., Xu, Z., Ge, A., Gao, Y., Fan, J., Song, H., Liu, B., Li, J., Wang, C., Hu, M. 2018; 36 (22): 5237-5243
  • Femtosecond laser pulse generation with self-similar amplification of picosecond laser pulses OPTICS EXPRESS Song, H., Liu, B., Chen, W., Li, Y., Song, Y., Wang, S., Chai, L., Wang, C., Hu, M. 2018; 26 (20): 26411-26421

    Abstract

    Compressing picosecond laser pulses to the femtosecond level is an attractive shortcut for obtaining femtosecond laser pulses. However, dechirped pulses generated by nonlinear compression with self-phase modulation (SPM) show obvious pedestals, which are induced by nonlinear chirp accumulation in spectral broadening process and cannot be easily suppressed. Here, we report systematic numerical simulations and experimental studies on self-similar amplification of picosecond pulses in a short gain fiber for obtaining ~100-fs laser pulses with nearly transform-limited (TL) temporal quality. It is demonstrated that self-similar amplification with picosecond seed pulses is only sensitive to pulse duration and pulse energy. Based on this optimization guideline, we built a compact self-similar amplification fiber system with a picosecond fiber laser as the seed source. This system outputs 66-fs pulses with 6.1-W average power at a repetition rate of 30 MHz. Due to the linear chirp produced in self-similar evolution process, compressed pulses show nearly TL temporal quality. It promises an efficient way of obtaining high-quality femtosecond laser pulses from a picosecond laser source.

    View details for DOI 10.1364/OE.26.026411

    View details for Web of Science ID 000446055500078

    View details for PubMedID 30469729

  • Femtosecond Fiber Amplification System Based on Third-Order Dispersion Compensation Technique LASER & OPTOELECTRONICS PROGRESS Hao Jingyu, Liu Bowen, Song Huanyu, Wen Liang, Niu Jia, Chai Lu, Hu Minglie, Wang Qingyue 2018; 55 (5)
  • Femtosecond Laser Pulse Generation from Picosecond Laser Source with Self-Similar Amplification Song, H., Chen, W., Song, Y., Hu, M., Liu, B., IEEE IEEE. 2018
  • High Damage Threshold Semiconductor Saturable Absorber Mirror for Fiber Lasers Wang, Y., Lin, N., Gao, W., Song, H., Hu, M., Li, H., Bao, W., Ma, X., Zhang, Z., IEEE IEEE. 2018
  • Intensity and temporal noise characteristics in femtosecond optical parametric amplifiers OPTICS EXPRESS Chen, W., Fan, J., Ge, A., Song, H., Song, Y., Liu, B., Chai, L., Wang, C., Hu, M. 2017; 25 (25): 31263-31272

    Abstract

    We characterize the relative intensity noise (RIN) and relative timing jitter (RTJ) between the signal and pump pulses of optical parametric amplifiers (OPAs) seeded by three different seed sources. Compared to a white-light continuum (WLC) seeded- and an optical parametric generator (OPG) seeded OPA, the narrowband CW seeded OPA exhibits the lowest root-mean-square (RMS) RIN and RTJ of 0.79% and 0.32 fs, respectively, integrated from 1 kHz to the Nyquist frequency of 1.25 MHz. An improved numerical model based on a forward Maxwell equation (FME) is built to investigate the transfers of the pump and seed's noise to the resulting OPAs' intensity and temporal fluctuation. Both the experimental and numerical study indicate that the low level of noise from the narrowband CW seeded OPA is attributed to the elimination of the RIN and RTJ coupled from the noise of seed source, being one of the important contributions to RIN and timing jitter in the other two OPAs. The approach to achieve lower level of noise from this CW seeded OPA by driving it close to saturation is also discussed with the same numerical model.

    View details for DOI 10.1364/OE.25.031263

    View details for Web of Science ID 000417591100042

    View details for PubMedID 29245803

  • Practical 24-fs, 1-mu J, 1-MHz Yb-fiber laser amplification system OPTICS EXPRESS Song, H., Liu, B., Li, Y., Song, Y., He, H., Chai, L., Hu, M., Wang, C. 2017; 25 (7): 7559-7566

    Abstract

    We develop a practical femtosecond polarization-maintaining fiber laser amplification system with a standard double-cladding fiber technique, enabling 24-fs transform-limited pulses with 1-μJ pulse energy at a 1-MHz repetition rate. The laser system is based on a hybrid amplification scheme. Chirped-pulse amplification is employed in the pre-amplifier stage to supply high-quality pulses with enough energy for the main-amplifier, where nonlinear amplification is utilized to broaden the output spectrum. To obtain a dechirped pulse with high quality and short duration, a pre-shaper is inserted between the two amplification stages to adjust the pre-chirp, central wavelength, and pulse energy of the signal pulses in the main amplifier for optimizing pulse evolution. As a result, temporal pedestal free sub-ten-cycle high-energy laser pulses can be routinely obtained. In the end, the advantages of this novel laser source are demonstrated in the experiments on enhanced damage effect to cells co-cultured with gold nanorods.

    View details for DOI 10.1364/OE.25.007559

    View details for Web of Science ID 000398536000037

    View details for PubMedID 28380877

  • Optimization of Nonlinear Compensation in a High-Energy Femtosecond Fiber CPA System by Negative TOD Fiber IEEE PHOTONICS JOURNAL Song, H., Liu, B., Wen, L., Wang, C., Hu, M. 2017; 9 (2)
  • Investigation of photodamage by femtosecond laser to cells via gold nanorods JOURNAL OF INNOVATIVE OPTICAL HEALTH SCIENCES Li, Y., He, H., Song, H., Liu, B., Hu, M., Wang, C. 2017; 10 (1)