Intracavity frequency-doubled degenerate laser
  We develop a green light source with low spatial coherence via intracavity frequency doubling of a solid-state degenerate laser. The second harmonic emission supports many more transverse modes than the fundamental emission, and exhibit lower spatial coherence. A strong suppression of speckle formation is demonstrated for both fundamental and second harmonic beams. Using the green emission for fluorescence excitation, we show the coherent artifacts are removed from the full-field fluorescence images. The high power, low spatial coherence and good directionality makes the green degenerate laser an attractive illumination source for parallel imaging and projection display. 
Seng Fatt Liew, Sebastian Knitter, Sascha Weiler, Jesus Fernando   Monjardin-Lopez, Mark Ramme, Brandon Redding, Michael A. ...
physics.optics