Fig. 3: Synthesis and characterization of STLG wavepackets and its mode conversion.
From: Spatiotemporal optical vortices with controllable radial and azimuthal quantum numbers
a Concept of STLG wavepacket synthesis based on complex-amplitude modulation technique. The computer-generated hologram (CGH) embedded on the SLM comprises four components: (1) the phase distribution of a spatial-spectral LG mode; (2) a GDD phase for managing the pre-chirp of input pulse and controlling the balance diffraction and dispersion; (3) a phase-only diffraction grating whose phase depth modulated by the modulus of Eq. (2) (see Methods); (4) an astigmatic phase. The synthetic CGH can realize a complex-amplitude modulation, wherein the grating phase depth and delay controls the intensity and wavefront of incident pulsed beam, respectively57,58. b Optical setup for synthesizing and characterizing STLG wavepackets. The apparatus comprises three sections: (i) 2D ultrafast holographic pulse shaper consisting of a diffraction grating, a cylindrical lens and an SLM; (ii) a pulse compressor system consisting of a parallel grating pair; (iii) a time delay line system for fully reconstructing 3D profile of generated ST wavepacket. PBS, polarized beam splitter; HWP, half-wave plate; BS, beam splitter.
