Generation of Integer and Fractional Vortex Beams based on Liquid Crystal electronically reconfigurable Spiral Phase Plates

The manufacturing and characterization of a large-size 72-electrode liquid crystal-based reconfigurable spiral phase plate (SPP) is presented. The SPP is addressed by a custom-made driver with 72 independent channels, which allows for the generation of any arbitrary integer or fractional optical vortex beam with topological charges ranging from –36 to +36. The 25 mm diameter device is fabricated using direct laser writing, leading to a fill factor over 99%. The device performance and flexibility exceed any previous transparent reconfigurable SPP in terms of size, tuning range and fill factor. The device and the light path have been simulated using the angular spectrum propagation method, showing excellent correspondence.