Generating fast switchable optical vortices by beam combining

We present a novel method to generate fast switchable optical vortex by beam combining. Optical vortex is generated by the coherent superposition of Gaussian beams, and vortex mode switching is achieved by phase modulating each Gaussian beam with an electro-optic phase modulator (EOPM). We analyze the effects of different parameters on the combined optical vortex quality and use a spiral phase plate to measure the beam combining efficiency. The results show that the Gaussian beam waist radius, the beam-arrays, and the translation distance all have a substantial effect on the combined beam quality and combining efficiency, an efficiency of over 80% can be achieved by choosing parameters appropriately. And the rate of vortex mode switching can increase from ∼100Hz (traditional method) to ∼1GHz (EOPM).