Reduced speckle shows promise for illumination and holography

According to the team, the method of altering compact semiconductor lasers will make them more practical for illumination and holography.

Semiconductor technology allows for all elements of a laser to be packed into a micrometre-scale device. This includes an optically active, light amplification region with a highly reflective mirror on each side.

One such device is the vertical-cavity surface emitting laser (VCSEL). These are built by precisely placing, or growing, alternating layers of semiconductor on a substrate to create a highly reflective stack. The active material is then grown on top, followed by a second reflective stack. Laser light can then be emitted from the top of the device.

According to KAUST, VCSELs are advantageous because hundreds can be created and used on the same substrate simultaneously. The beam, however, is prone to a speckle-like profile, which makes it unsuitable for applications including lighting, holography, projection and displays. These require uniform light in the plane perpendicular to the direction of beam propagation.