In this letter, we report the demonstration of terawatt (TW)-scale femtosecond vortex laser pulses based on noncollinear optical parametric chirped-pulse amplification (OPCPA) centered at 800 nm.To the best of our knowledge, this is the first experimental study of amplification for OPCPA-based vortex pulses to achieve a powerful ultrafast (TWscale) vortex pulse output.In this experiment, a 0.5-mJ broadband chirped vortex pulse was amplified to 47 mJ with a 15-mm-long LiB 3 O 5 crystal.The double-pass grating pair compressor with an efficiency of 65% maintained the beam vortex, and a pulse of width 30.1 fs was obtained, corresponding to a peak power of 1.02 TW.This laser can be used in studies on nonlinear optics and relativistic laser-plasma interactions, compact plasmabased accelerators, and light sources.

We theoretically and experimentally demonstrate that high-purity Laguerre-Gaussian beams can be efficiently obtained from Gaussian vortex beams using a typical 4F spatial filtering optical system, in which spatial filtering does not affect the spiral phase and the energy loss is very small. In the Fourier frequency domain, aperture filtering specifically removes the high-frequency component corresponding to the central singularity region. In the spatial domain, aperture filtering corresponds to a convolution, which can smooth the central singularity region. This approach is simple and effective and has practical implementations in the generation and amplification of relativistic vortex beams.

We present direct experimental observation of the morphological evolution during the formation of nanogratings with sub-100-nm periods with the increasing number of pulses. Theoretical simulation shows that the constructive interference of the scattering light from original nanoplanes will create an intensity maximum located between the two adjacent nanoplanes, resulting in shortening the nanograting period by half. The proposed mechanism explains the formation of nanogratings with periods beyond those predicted by the nanoplasmonic model.