Spatially resolved characterization of the coherence area in the incoherent emission regime of a broad-area vertical-cavity surface-emitting laser

The spatial coherence area of a pulsed broad-area vertical-cavity surface-emitting laser is measured by using a reversing wavefront interferometer. The studies have shown that the coherence area is limited in size by the radial temperature gradient in the device and the optimum speckle reduction factor is inversely proportional to the coherence radius.