A vortex laser with tunable spatial coherence and its application in imaging

Partially coherent vortex beams are a class of complex structured light characterized by finite spatial coherence. Their unique multi-dimensional degrees of freedom are actively driving advancements in fields like light manipulation. Conventionally, partially coherent vortex beams from a resonator are difficult to be tailored effectively. In this work, a compact plano–concave resonator is constructed to obtain a high-power, partially coherent vortex laser (PCVL). By introducing controllable defect spots on the cavity mirror and jointly adjusting the pump power and the spatial scale of the pump spot, multimode competition and statistical superposition states can be induced inside the cavity. The speckle contrast of the PCVL is tunable from 0.7 to 0.23, with the corresponding M2 values increasing from (2.19, 2.15) to (11.91, 11.97), the ratio of the spatial coherence width to beam waist width decreasing from 0.68 to 0.32, and the maximum average output power reaching 1.8 W. Effective suppression of speckle noise and enhancement of imaging performance have been achieved in optical imaging applications. This work provides an effective route for the generation of high-power compact partially coherent laser sources in optical field manipulation.