![]() “We can use the light emitted in a better way rather than just turning them off and on.” “In applications where space is valuable, steering light emission with low-size-and-weight metasurface-LED displays could be made possible in the future with this technology,” said Prasad Iyer, Sandia scientist and lead author of the research paper. One low-power use would be to brighten augmented reality military helmet screens. The proof-of-principle work paves the way for developments in a range of nanophotonics and ultrafast optics applications. In a final device that could be commercialized, you would want to do this with additional contacts/electrodes, so this would be a compact, electrically driven device.”Ī metasurface sample is used for the beam-steering with each reflective patch containing thousands of meta-atoms designed to dynamically steer incoherent light. The optical control was our way to create this dynamic index modulation and served the purpose of demonstrating the proof of concept. “There is no current technology that can provide this in a reconfigurable way. “For this concept to work, one has to create a large modulation of the refractive index in the shape of a periodic sawtooth profile superimposed on the metasurface,” Brener told Photonics Media. ![]() Similar to laser-based steering, the steered beam restrained the tendency of incoherent light to spread over a wider viewing angle and instead produced bright light at a distance. Using a control optical pulse, they changed, or reconfigured, the way that the surface reflected light and steered the lightwaves emitted from the quantum dots in different directions over a 70° range for less than one-trillionth of a second. The researchers started with a gallium arsenide semiconductor metasurface embedded with indium arsenide quantum dot light sources. Ideally, one would want a semiconductor device that could emit light like an LED, steer the light emission to a set angle by applying a control voltage, and shift the steering angle at the fastest speed possible. According to Sandia researcher Igal Brener, although there have been prior demonstrations of static metasurfaces that can emit incoherent light which could be steered to a particular angle, that angle was fixed by design. The researchers manipulated incoherent light using metasurfaces made from tiny building blocks of semiconductors, called meta-atoms, that can be designed to reflect light efficiently. A beam of light from a laser, so-called coherent light, does not spread and diffuse because the photons have the same frequency and phase.Īs a red beam of light is reflected in an arch, Prasad Iyer (right) and Igal Brener demonstrate optical hardware used for beam-steering experiments at Sandia National Laboratories’ Center for Integrated Nanotechnologies. So-called incoherent light, which is emitted by sources such as incandescent light bulbs and LEDs, takes its name because the photons are emitted with different wavelengths and in a random fashion. The ability to control incoherent light with a semiconductor device could allow low-power, low-cost sources such as LEDs or flashlight bulbs to replace laser beams in technologies such as holograms, remote sensing, self-driving cars, and high-speed communication. ![]() ALBUQUERQUE, N.M., ApA research team at Sandia National Laboratories has demonstrated a technique that dynamically steers light pulses from conventional incoherent light sources. ![]()
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