Chips That Can Steer Light

If you want to create a moving light source, you have a few possibilities. One is to mount a light emitter in some kind of mechanical housing — the approach used in, for example, theatrical spotlights, which stage hands swivel and tilt to track performers. Another possibility, however, is to create an array of light emitters and vary their “phase” — the alignment of the light waves they produce. The out-of-phase light waves interfere with one another, reinforcing each other in some directions but annihilating each other in others. The result is a light source that doesn’t move, but can project a beam in any direction.