Top Developing 3D live hologram technology to save lives in field hospitals

3D holograms from your phone, television, or favorite droid have been promised for decades but, despite being of great interest, have yet to materialize. The applications for them are far-reaching, particularly in the medtech field where real time, dynamic holograms are predicted to shorten operation times and deliver better surgical outcomes.
Lead author Wei Wen Wong says, "This is the way forward towards low power consumption, on-chip microlasers with tunable emission directionality. This new development removes one of the key obstacles standing in the way of realizing 3D holograms."

"It is our hope that this novel device will one day be integrated into a device small enough and cheap enough for medical professionals slip into their pocket as they travel to remote areas, allowing full color dynamic holograms to be projected from field operating tables."

TMOS Chief Investigator Hoe Tan says, "The development of dynamic holograms is one of our Center's flagship projects. Teams across all five participating universities are working together to make this a reality. The next steps for our research is to create an array of pixels where the wavefront and beam shape can be controlled individually and dynamically tuned.
The ability to precisely control the various properties of laser light is critical to much of the technology that we use today, from commercial virtual reality (VR) headsets to microscopic imaging for biomedical research. Many of today's laser systems rely on separate, rotating components to control the wavelength, shape and power of a laser beam, making these devices bulky and difficult to maintain.
Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a single metasurface that can effectively tune the different properties of laser light, including wavelength, without the need of additional optical components. The metasurface can split light into multiple beams and control their shape and intensity in an independent, precise and power-efficient way.

The research opens the door for lightweight and efficient optical systems for a range of applications, from quantum sensing to VR/AR headsets.

"Our approach paves the way to new methods to engineer the emission of optical sources and control multiple functions, such as focusing, holograms, polarization, and beam shaping, in parallel in a single metasurface," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper.

The research was published recently in Nature Communications.

The tunable laser has just two components—a laser diode and a reflective metasurface. Unlike previous metasurfaces, which relied on a network of individual pillars to control light, this surface uses so-called supercells, groups of pillars which work together to control different aspects of light.
When light from the diode hits the supercells on the metasurface, part of the light is reflected back, creating a laser cavity between the diode and the metasurface. The other part of the light is reflected into a second beam that is independent from the first.

"When light hits the metasurface, different colors are deflected in different directions," said Christina Spägele, a graduate student at SEAS and first author of the paper. "We managed to harness this effect and design it so that only the wavelength that we selected has the correct direction to enter back in the diode, enabling the laser to operate only at that specific wavelength."