Observation of Spatial Coherence Collapse in High-Power, Broad-Area Lasers Using Fiber-Assisted Self-Heterodyning

In this work, a high-resolution, self-heterodyne,RF measurement of a broad-area laser is spatially resolved using an optical fiber at a range of power levels. Three separate spatial regimes of operation are revealed as power is increased: conventional modes, spatial coherence collapse, and cavity-assisted filamentation.