Controlling a laser beam’s shape electronically

MIT Technology Review : A laser works by bouncing light back and forth in a lasing cavity. The cavity is filled with a gain medium that is used to amplify a specific wavelength of light, which is then directed out of the cavity as a narrow, coherent beam. How the intensity of the light varies across the beamâmdash;the laser’s “shape"âmdash;can be controlled by custom optics outside of the cavity. However, they are expensive and require calibration when they are changed. Now Sandile Ngcobo of the University of KwaZuluâNatal in South Africa and his colleagues have found a way to simplify controlling laser beam shapes. To the inside of the lasing cavity they added a spatial light modifier that can be controlled electronically to shape the light while it is being amplified. Because the researchers can control the shaping with a computer, they are calling their device a digital laser. The result is a laser that can be shaped in real time and that has nearly unlimited applications.