ABSTRACT
A transmissive adaptable optical setup to generate a range of perfect vortex beams (PVBs) carrying different topological charges (TC) without using moving parts is presented. The setup is composed of an ad hoc transparent reconfigurable liquid crystal (LC) spiral phase plate (SPP), a refractive axicon and a convergent refractive lens. The LC SPP electrodes are manufactured ablating indium-tin oxide (ITO) glass substrates using direct laser writing (DLW) resulting in a very high fill factor device. In-house tailored electronics drive the 72 LC SPP electrodes giving rise to 72 different configurations with orbital angular momentum. In this work, the generation of PVBs with 36 positive or 36 negative TCs using this optical setup is accomplished.
ABSTRACT
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 -24 to +24. The 25 mm diameter device is fabricated using direct laser writing, leading to a fill factor over 99%. The device performance and flexibility exceed 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.
