296 / 2023-04-25 22:29:28

Laser compression via fast-exending plasma gratings

极端光下的基础物理学 > 基础物理-I

We present a new method  for compressing laser pulses by fast-extending plasma gratings (FEPGs), which are created by ionizing a hypersonic wave generated by stimulated Brillouin scattering in a background gas. Ionized by a short laser pulse, the phonon forms a light-velocity FEPG to fully reflect a resonant pump laser. As the reflecting surface moves with the velocity of light, the reflected pulse is temporally overlapped and compressed. This talk has 2 sections: firstly, it is about the compression of laser from picosecond to a few optical cycles by FEGPs with a constant average plasma density. Secondly, it includes a new regime to further compress the laser pulse to attosecond by gradient FEPGs, which are formed in the gas-plasma mixture zone of the laser-induced FEPGs. Different from constant FEPGs, the gradient FEPG only has one point satisfying the Bragg condition for the pump wavelength, so it confines the reflect pump within a sub-cycle gating. In combination with the frequency upconversion in the gradient plasma, the reflected pumps form coherent and wideband isolated attosecond pulses(IAPs). Bothe of these 2 regimes are demonstrated feasible by the 1D-3D particle-in-cell simulation, showing a great potential to produce high-peak-power laser pulses and high-energy IAPs.