Experimental demonstration of intracavity multiaxial geometric mode structure manipulation

Coherent wave multiaxial geometric modes (MAGMs) are a type of complex structured light characterized by ray-wave duality. Multiple spatial degrees-of-freedom of MAGMs are attractive for some advanced areas such as high-capacity optical communications. Conventionally, transverse light field coupled to ray-trajectories of geometric mode from lasers is hard to be tailored. Here, intracavity manipulation of the transverse structure of MAGMs is experimentally demonstrated. A spot-defect was employed to realize loss control and couple various structured transverse modes including Hermite-Gaussian modes and Laguerre-Gaussian modes to rays of MAGMs. More interestingly, we experimentally demonstrate that sub-MAGMs can also be coupled to ray-trajectories of MAGMs, and multi-ray geometric modes twisted light can be obtained. This work reveals that the dimension of light field can be further expanded and open perspectives on high-dimensional structured light physics and applications.