Experimental Demonstration of Laser Guiding and Wakefield Acceleration in a Curved Plasma Channel.

Curved plasma channels have been proposed to guide intense lasers for various applications, such as x-ray laser emission, compact synchrotron radiation, and multistage laser wakefield acceleration [e.g. J.

Divergence control of relativistic harmonics by an optically shaped plasma surface.

The unique spatial and temporal properties of relativistic high harmonics generated from a laser-driven plasma surface allow them to be coherently focused to an extremely high intensity reaching the Schwinger limit. The ultimately achievable intensity is limited by the harmonic wavefront distortions during the interactions. Here we demonstrate experimentally that the harmonic divergence can be controlled by an optically shaped plasma surface with a prepulse that has the same spatial and temporal distribution as the main laser pulse.

Demonstration of laser-produced neutron diagnostic by radiative capture gamma-rays.

We report a new scenario of the time-of-flight technique in which fast neutrons and delayed gamma-ray signals were both recorded in a millisecond time window in harsh environments induced by high-intensity lasers. The delayed gamma signals, arriving far later than the original fast neutron and often being ignored previously, were identified to be the results of radiative captures of thermalized neutrons. The linear correlation between the gamma photon number and the fast neutron yield shows that these delayed gamma events can be employed for neutron diagnosis.

A two-dimensional angular-resolved proton spectrometer.

We present a novel design of two-dimensional (2D) angular-resolved spectrometer for full beam characterization of ultrashort intense laser driven proton sources. A rotated 2D pinhole array was employed, as selective entrance before a pair of parallel permanent magnets, to sample the full proton beam into discrete beamlets. The proton beamlets are subsequently dispersed without overlapping onto a planar detector.

Demonstration of Coherent Terahertz Transition Radiation from Relativistic Laser-Solid Interactions.

Coherent transition radiation in the terahertz (THz) region with energies of sub-mJ/pulse has been demonstrated by relativistic laser-driven electron beams crossing the solid-vacuum boundary. Targets including mass-limited foils and layered metal-plastic targets are used to verify the radiation mechanism and characterize the radiation properties. Observations of THz emissions as a function of target parameters agree well with the formation-zone and diffraction model of transition radiation.

Single-shot measurement of >10¹⁰ pulse contrast for ultra-high peak-power lasers.

Real-time pulse-contrast observation with a high dynamic range is a prerequisite to tackle the contrast challenge in ultra-high peak-power lasers. However, the commonly used delay-scanning cross-correlator (DSCC) can only provide the time-consumed measurements for repetitive lasers. Single-shot cross-correlator (SSCC) becomes essential in optimizing laser systems and exploring contrast mechanisms.

Long lifetime air plasma channel generated by femtosecond laser pulse sequence.

Lifetime of laser plasma channel is significantly prolonged using femtosecond laser pulse sequence, which is generated from a chirped pulse amplification laser system with pure multi-pass amplification chain. Time-resolved fluorescence images and electrical conductivity measurement are used to characterize the lifetime of the plasma channel. Prolongation of plasma channel lifetime up to microsecond level is observed using the pulse sequence.