Phased arrays consist of multiple antennas, all driven from a single source. By combining the output from all those antennas, you can make the light very directional, or give it a particular shape. Typically, phased arrays use radio light: big radar installations use them, as does the Very Large Array (VLA) of radio telescopes. A lab now has produced a phased array of 4,096 antennas on a single chip, which emit visible light instead—a potentially profound breakthrough in nanoscale photonic devices.

Modern nanoscale technology is now allowing researchers to create phased arrays for optical (visible) light. Jie Sun and colleagues fabricated a phased array of 4,096 microscopic antennas on a single silicon chip. This allowed them to shape the output waveform, so they could transmit an image of the MIT logo by combining the light from each tiny antenna in precise ways—something that could not be done with (say) a similar array of LEDs. Potential applications for this research include biomedical imaging, holography, and laser communications. [Read more…]