No abstract

No abstract

Inverse Compton scattering between ultra-relativistic electrons and an intense laser field has been proposed as a major route to generate compact high-brightness and high-energy γ-rays. Attributed to the inherent synchronization mechanism, an all-optical Compton scattering γ-ray source, using one laser to both accelerate electrons and scatter via the reflection of a plasma mirror, has been demonstrated in proof-of-principle experiments to produce a x-ray source near 100 keV. Here, by designing a cascaded laser wakefield accelerator to generate high-quality monoenergetic e-beams, which are bound to head-on collide with the intense driving laser pulse via the reflection of a 20-um-thick Ti foil, we produce tunable quasi-monochromatic MeV γ-rays (33% full-width at half-maximum) with a peak brilliance of ~3 × 1022 photons s−1 mm−2 mrad−2 0.1% BW at 1 MeV. To the best of our knowledge, it is one order of magnitude higher than ever reported value of its kinds in MeV regime. This compact ultrahigh brilliance γ-ray source may provide applications in nuclear resonance fluorescence, x-ray radiology and ultrafast pump-probe nondestructive inspection.

In this paper, we report the recent progress on the $1~\text{PW}/0.1~\text{Hz}$ laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF). The SULF-1 PW laser beamline is based on the double chirped pulse amplification (CPA) scheme, which can generate laser pulses of 50.8 J at 0.1 Hz after the final amplifier; the shot-to-shot energy fluctuation of the amplified pulse is as low as 1.2% (std). After compression, the pulse duration of 29.6 fs is achieved, which can support a maximal peak power of 1 PW. The contrast ratio at $-80~\text{ps}$ before main pulse is measured to be $2.5\times 10^{-11}$ . The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor. The maximal focused peak intensity can reach $2.7\times 10^{19}~\text{W}/\text{cm}^{2}$ even with an $f/26.5$ off-axis parabolic mirror. The horizontal and vertical angular pointing fluctuations in 1 h are measured to be 1.89 and $2.45~\unicode[STIX]{x03BC}\text{rad}$ , respectively. The moderate repetition rate and the good stability are desirable characteristics for laser–matter interactions. The SULF-1 PW laser beamline is now in the phase of commissioning, and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented. The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.

By combining cross-polarized wave generation and femtosecond optical parametric amplification, a high-contrast front end featuring ultrahigh contrast, a broadband spectrum, an excellent beam profile, and good stability is built for a 10-PW-level Ti:sapphire laser in the Shanghai Superintense Ultrafast Laser Facility (SULF-10PW laser). The front end can deliver a cleaned pulse with a 110 μJ energy at 1 kHz, and the bandwidth of the cleaned pulse exceeds 60 nm (FWHM), which can support a 17 fs compressed pulse duration. The measured output energy fluctuation in one hour is <1.8% in rms value. The measurement-limited contrast is 10 at 3 ps before the main pulse. Utilizing the high-contrast front end, single-shot contrast at 10 level has been demonstrated in the SULF-10PW laser at a 24 fs pulse duration.

No abstract

No abstract

Here, we report the recent progress on the front end developed for the 100 PW-class laser facility. Using 3 stages of optical parametric chirped-pulse amplification (OPCPA) based on lithium triborate (LBO) crystals, we realized a 5.26 J/0.1 Hz amplified output with a bandwidth over 200 nm near the center wavelength of 925 nm. After the compressor, we obtained a pulse duration of 13.4 fs. As the compression efficiency reached 67%, this OPCPA front end could potentially support a peak power of 263 TW at a repetition rate of 0.1 Hz. To the best of our knowledge, among all the 100 TW-level OPCPA systems, it shows the widest spectral width, the shortest pulse duration, and it is also the first OPCPA system working at a repetition-rate mode.