Quadrant-separable multi-singularity vortices manipulation by coherent superposed mode with spatial-energy mismatch.

We propose a new method of phase-singularities manipulation in optical vortices carrying orbital angular momentum (OAM), namely, quadrant-separable multi-singularity manipulation (QSMSM). In QSMSM, the positions of partial vortices in a quadrant region can be manipulated, while the singularities in other regions remain unchanged. The basic model of the multi-singularity OAM beam is obtained by the principle of coherent superposition of two Hermite-Gaussian modes with spatial mismatch. The actual multi-singularity beams are generated by external modulation with a spatial light modulator. The distribution of vortices trajectory can be controlled by the energy mismatch degree and the spatial mismatch degree. The vortices in a quadrant region can be independently manipulated by partially controlling the energy mismatch degree. The technology of partially tuning singularities in QSMSM improves the flexibility of vortices control and has great potential in applications of optical tweezers and optical modulators.