Flat optical device has applications in augmented and virtual reality, ultra-high resolution microscopy, holography
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a flat optical component that is simultaneously a metalens, a microscope objective that can resolve details smaller than a wavelength of light, and an optical vortex and hologram generator. Each functionality is controlled by a different wavelength of light.
"The breakthrough of this new flat optical device is that it can radically change its function based on the wavelength of light it reflects," said Federico Capasso, the Robert Wallace Professor of Applied Physics at SEAS and senior author of the research. "By tying functionality to wavelength, we have opened up a whole range of new possibilities for metasurfaces."
The research was published in Nano Letters.
"In this research, we decoupled functions at different wavelengths," said Zhujun Shi, first author of the paper and graduate student at SEAS. "Compared to previous flat optical devices, this device has an extra degree of freedom that you can tune at different wavelengths. For example, at one color, this lens behaves like a traditional metalens but at another wavelength, it generates a vortex beam."
The Harvard Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.
The lens builds on previous technology developed in the Capasso Lab, which used different polarized light to change the function of a lens. But since there are only two forms of circularly polarized light -- clockwise or counterclockwise -- the researchers could embed only two different functions in the metasurface.
"By controlling the device function with wavelength, rather than polarization that is bound to two states, we have dramatically increased the information capacity of the lens," said Mohammadreza Khorasaninejad, co-first author of the paper and former postdoctoral fellow in the Capasso Lab. "With this technology, we demonstrated an achromatic metalens in blue, green, yellow and red wavelengths, two beam generators, and a full-color hologram."
While this is not the first lens to tie function to wavelength, it is the most efficient. Previous wavelength-dependent metalenses encoded different functions in different areas of the surface; for example, red light would be focused in one quadrant and blue light in another.
With this technology, Shi and the rest of the team engineered the individual nanoscale optical elements to embed functionality at the local level, across the entire lens.
"By encoding everything locally, in a single layer, we improved efficiency from 8 percent demonstrated in previous wavelength-dependent metasurfaces to more than 30 percent," said Yao-Wei Huang, co-first author of the paper and postdoctoral fellow at SEAS.
Next, the team aims to improve that efficiency even further and develop a transmitting, rather than a reflective lens.
This research was co-authored by Charles Roques-Carmes, Alexander Y. Zhu, Wei Ting Chen, Vyshakh Sanjeev, ZhaoWei Ding, Michele Tamagnone, Kundan Chaudhary, Robert C. Devlin, and Cheng-Wei Qiu. It was supported in part by the Air Force Office of Scientific Research.
Leah Burrows | EurekAlert!
Researchers discover link between magnetic field strength and temperature
21.08.2018 | American Institute of Physics
Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
21.08.2018 | Ecology, The Environment and Conservation
21.08.2018 | Life Sciences
21.08.2018 | Power and Electrical Engineering