Light-bending silicon chip shows projector potential

The chip was developed by Ali Hajimiri, Thomas G. Myers Professor of Electrical Engineering, and researchers in his laboratory and results were presented at the Optical Fiber Communication (OFC) conference in San Francisco on March 10.

Traditional projectors pass a beam of light through an image, using lenses to map each point of the picture to corresponding, expanded points on a screen. The Caltech chip is claimed to eliminate the need for bulky and expensive lenses and bulbs and instead uses a so-called 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 and his colleagues were able to bypass traditional optics by manipulating the coherence of light, a property that allows the researchers to bend the light waves on the surface of the chip without lenses or the use of any mechanical movement. If two waves are coherent in the direction of propagation the waves combine, resulting in one wave, a beam with twice the amplitude and four times the energy as the initial wave, moving in the direction of the coherent waves.