Optical vortices by an adaptive spiral phase plate

An Adaptive Spiral Phase Plate (ASPP) based on liquid crystal (LC) and the transmission electrode technique is theoretically and experimentally demonstrated. This ASPP design enables the generation of high-quality optical vortices with topological charges ranging from +/- 1 to +/- 4 using a single device, with higher charges being directly achievable by employing higher-birefringence LC or thicker cells. The continuous reconfigurability of the optical phase shift, achieved through a simple control mechanism involving only two low voltages and 100 electrodes that distribute the voltage, sets this device as an accurate approximation to a continuous ASPP. The measured conversion efficiency ranges between almost 100% and 95% for the first and fourth topological charges, respectively. This device offers remarkable advantages, such as complete reconfigurability, allowing adjustment of operating wavelengths and topological charges. The fabrication process mirrors that of a standard LCD cell, ensuring a cost-effective and reliable solution. In summary, the proposed ASPP is a key advancement, providing superior light conversion efficiency, simplicity, and the capability for on-the-fly reconfiguration in various optical applications.