A universal and versatile terahertz field manipulation mechanism by manipulating near-infrared phases with a dislocation scheme

This paper presents a universal and versatile terahertz (THz) wavefront-phase manipulation by manipulating the two-dimensional phases of the near-infrared pulses. The near-infrared manipulation enables independent controls of two kinds of wavefront-phases with a two-dimensional phase modulator along two orthogonal directions. An implementation strategy of the near-infrared manipulation is further introduced by a dislocation scheme including two plates with conjugated-phase functions to output two collinear pulses with orthogonal polarizations and conjugated modulated phases. The manipulated phases can be converted to THz region by type-II phase-matched difference frequency conversion. A proof-of-principle experiment has confirmed the flexible and multiple near-infrared wavefront-phase manipulation and the conversion to THz region via dynamically generating and controlling THz vortex, Bessel, and vortex-Bessel fields with tunable topological charge and "diffraction-free" propagation distance. This work provides a powerful wavefront-phase manipulation, particularly in spectral regions where direct phase manipulation is technically challenging, e.g. in THz region.