Caltech breakthrough allows you to paint with light -

New chips will let you  project a bright, clear image onto a wall or a big screen  thanks to a light-bending silicon chip developed by researchers at Caltech.

Developed by Ali Hajimiri, Thomas G. Myers Professor of Electrical Engineering, and researchers in his laboratory the chip was shown off at the Optical Fiber Communication (OFC) conference in San Franciscp.

Traditional projectors pass light through a tiny image, using lenses to map each point of the small picture to points on a large screen. The Caltech chip ditches the bulky lenses and bulbs and uses an integrated optical phased array (OPA) to project the image electronically with only a single laser diode as light source and no mechanically moving parts.

Hajimiri did all this by bending the light waves on the surface of the chip without lenses or the use of any mechanical movement.

According to Solid State Technology  it is all to do with waves of light.

Apparently, if two waves of light are exactly aligned they combine and make a beam with twice the amplitude and four times the energy as the initial wave, moving in the direction of the coherent waves.

If you change the timing of the waves, you can change the direction of the light beam. He said that it is like 10 people kneeling in line by a swimming pool slap the water at the exact same instant making make one big wave that travels directly away from them. If the 10 separate slaps are staggered there will still be one big, combined wave, but with the wave bending to travel at an angle.

Therefore, by using series of pipes for the light, dubbed phase shifters, the chip similarly slows down or speeds up the timing of the waves, thus controlling the direction of the light beam.

To form an image, electronic data from a computer are converted into multiple electrical currents; by applying stronger or weaker currents to the light within the phase shifter, the number of electrons within each light path changes.