Metalenses have been used to picture microscopic options of tissue and resolve particulars smaller than a wavelength of sunshine. Now they’re going larger.
Researchers on the Harvard John A. Paulson College of Engineering and Utilized Sciences (SEAS) have developed a 10-centimeter-diameter glass metalens that may picture the solar, the moon and distant nebulae with excessive decision. It’s the first all-glass, large-scale metalens within the seen wavelength that may be mass produced utilizing standard CMOS fabrication know-how.
The analysis is printed in ACS Nano.
“The power to precisely management the dimensions of tens of billions of nanopillars over an unprecedentedly massive flat lens utilizing state-of-the-art semiconductor foundry processes is a nanofabrication feat that opens thrilling new alternatives for area science and know-how,” stated Federico Capasso, the Robert L. Wallace Professor of Utilized Physics and Vinton Hayes Senior Analysis Fellow in Electrical Engineering at SEAS and senior creator of the paper.
Most flat metalenses, which use tens of millions of pillar-like nanostructures to focus gentle, are in regards to the dimension of a chunk of glitter. In 2019, Capasso and his staff developed a centimeter-scale metalens utilizing a method known as deep-ultraviolet (DUV) projection lithography,which initiatives and kinds a nanostructure sample that may be instantly etched into the glass wafer, eliminating the time-consuming writing and deposition processes that have been required for earlier metalenses.
DUV projection lithography is usually used to sample positive traces and shapes in silicon chips for smartphones and computer systems. Joon-Suh Park, a former graduate scholar at SEAS and present postdoctoral fellow in Capasso’s staff, demonstrated that the approach couldn’t solely be used to mass produce metalenses but in addition enhance their dimension for functions in digital and augmented actuality.
However making the metalens even bigger for functions in astronomy and free-space optical communications posed an engineering downside.
“There’s a main limitation with the lithography software as a result of these instruments are used to make laptop chips, so chip dimension is restricted to not more than 20 to 30 millimeters,” stated Park, co-first creator of the paper. “In an effort to make a 100-millimeter diameter lens, we would have liked to discover a means round this limitation.”
Park and the staff developed a method to sew collectively a number of patterns of nanopillars utilizing the DUV projection lithography software. By dividing the lens into 25 sections however utilizing solely the 7 sections of a quadrant contemplating the rotational symmetry, the researchers confirmed that DUV projection lithography might sample 18.7 billion designed nanostructures onto a 10-centimeter round space in a matter of minutes. The staff additionally developed a vertical glass etching approach that enables the creation of high-aspect ratio, smooth-sidewall nanopillars etched into glass.
“Utilizing the identical DUV projection lithography, one might produce large-diameter, aberration-correcting meta-optics and even bigger lenses on bigger glass diameter wafers because the corresponding CMOS foundry instruments turn out to be more and more accessible within the trade,” stated Quickly Wei Daniel Lim, a postdoctoral fellow at SEAS and co-first creator of the paper.
Lim performed a lead function within the full simulation and characterization of all of the doable fabrication errors that might come up throughout mass-manufacturing processes and the way they may affect the optical efficiency of metalenses.
After addressing doable manufacturing challenges, the researchers demonstrated the facility of the metalens in imaging celestial objects.
Mounting the metalens on a tripod with a shade filter and digicam sensor, Park and the staff took to the roof of Harvard’s Science Heart. There, they imaged the Solar, the moon and the North America nebula, a dim nebula within the constellation Cygnus about 2,590 gentle years away.
“We have been in a position to get very detailed photos of the Solar, the moon and the nebula which can be comparable to pictures taken by standard lenses” stated Arman Amirzhan, a graduate scholar within the Capasso Lab and co-author of the paper.
Utilizing solely the metalens, the researchers have been in a position to picture the identical cluster of sunspots as a NASA picture taken that very same day.
The staff additionally demonstrated that the lens might survive publicity to excessive warmth, excessive chilly and the extraordinary vibrations that will happen throughout an area launch with none harm or loss in optical efficiency.
Due to its dimension and monolithic glass composition, the lens is also used for long-range telecommunications and directed vitality transport functions.
The analysis is co-authored by Hyukmo Kang, Karlene Karrfalt, Daewook Kim, Joel Leger, Augustine Urbas, Marcus Ossiander and Zhaoyi Li. It was supported by the Protection Superior Analysis Tasks Company (DARPA) Grant No. HR00111810001 and the Air Drive Workplace of Scientific Analysis underneath Award No. FA9550-22-1-0312.
