Selective control of wavefront helicity in a side-pumped Nd:YVO4 vortex laser

Optical vortex modes, possessing a spiral wavefront, an annular intensity profile and orbital angular momentum, mħ (m is termed a topological charge), have been intensely investigated in various applications, such as an optical tweezer, quantum information processing, and laser ablation. Recently, we discovered that the wavefront helicity (clock-wise or counter clock-wise spiral direction) of the optical vortex can be transferred to melted metal through a laser ablation process, forming chiral metal nanoneedles [1]. These nanoneedles will open the possibility of new structured materials, such as chiral planer metamaterials.