Based on the non-coaxial interference of Bessel-Gaussian (BG) beams, a new complex-structured light field is formed. By varying the off-axis distance, phase difference, separation angle, and topological charges (TCs) of the component beams, we observed the splitting, generation, and annihilation of phase singularities. The net TCs of the composite light field is not always equal the sum of the TCs of the original beams. Different from the general single-ringed vortex beams, because BG beams have infinitely many rings, alternately positive and negative unit vortex chains arise in the interference region. Furthermore, the edge dislocations are unstable, by modulating the phase difference and separation angle, we observe controllable transitions between edge dislocations and vortex singularities. Beyond providing an effective method for studying composite vortex beam interference, our results are significant for laser calibration and complex particle manipulation.

In this study, an open-ring controllable Bessel vortex beam is theoretically and experimentally constructed with a power-exponent-phase vortex. Its distribution in the far field after being blocked with obstacles is subsequently investigated. In the far field, the beam exhibits different degrees of the open-loop effect following adjustments in the phase term of the power exponent. For an obstructed beam, the direction of the open loop is offset by a certain value, and different open-loop angles can be achieved for different blocking angles. The developed beam can be used to guide particles and avoid obstacles.

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Optical vortices (OVs) with controllable orbital angular momentum (OAM) distributions have potential applications in optical communication and optical manipulation. However, the source of optical vortices with segmented phase gradients generated by existing methods can be used only at a short distance because of their low power. In this study, based on coherent combining technology, we proposed a method to generate a controlled-phase optical vortex (COV). Compared with traditional OVs, the magnitude and direction of the local OAM of the COV are controllable. The transmission characteristics of the COV in free space were numerically examined using a split-step Fourier transform algorithm. We theoretically and experimentally proved the feasibility of the coherent combining technology to generate an COV and proved that it has the properties of non-diffraction and self-healing.

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