Spiral phase plate for generation of scalar vortex beam made on fused silica by laser-induced microplasma

Spiral phase plates are a common method, which provides direct efficient generation of beams carried orbital angular momentum from Gaussian beams. They are characterized by high efficiency and less complex structure compared to other optical elements used for vortex beams generation. In this paper, we propose to use laser-induced microplasma (a simple, reliable, and high-performance technology) for spiral phase plate fabrication on fused silica. Spiral phase plate fabricated for the wavelength of 1.06 μm was tested using registration of generated intensity distribution in the far field by CCD camera. Test results demonstrate that fabricated plate generates vortex beam with the topological charge equal to 1 and correlate with theoretical concept. The conversion efficiency of fabricated plate was determined by measuring the initial beam power and the transmitted beam through fabricated plate. It appeared to be ∼ 75%.