Nearly each automotive, practice and airplane that is been constructed since 1970 has been manufactured utilizing high-power lasers that shoot a steady beam of sunshine. These lasers are robust sufficient to chop metal, exact sufficient to carry out surgical procedure, and highly effective sufficient to hold messages into deep area. They’re so highly effective, in actual fact, that it is troublesome to engineer resilient and long-lasting elements that may management the highly effective beams the lasers emit.
At this time, most mirrors used to direct the beam in high-power steady wave (CW) lasers are made by layering skinny coatings of supplies with completely different optical properties. But when there’s even one, tiny defect in any of the layers, the highly effective laser beam will burn via, inflicting the entire machine to fail.
When you might make a mirror out of a single materials, it will considerably scale back the chance of defects and enhance the lifespan of the laser. However what materials could be robust sufficient?
Now, researchers on the Harvard John A. Paulson College of Engineering and Utilized Sciences (SEAS) have constructed a mirror out of one of many strongest supplies on the planet: diamond. By etching nanostructures onto the floor of a skinny sheet of diamond, the analysis staff constructed a extremely reflective mirror that withstood, with out harm, experiments with a 10-kilowatt Navy laser.
“Our one-material mirror method eliminates the thermal stress points which might be detrimental to standard mirrors, shaped by multi-material stacks, when they’re irradiated with massive optical powers,” mentioned Marko Loncar, the Tiantsai Lin Professor of Electrical Engineering at SEAS and senior creator of the paper. “This method has potential to enhance or create new purposes of high-power lasers.”
The analysis is printed in Nature Communications.
Loncar’s Laboratory for Nanoscale Optics initially developed the method to etch nanoscale buildings into diamonds for purposes in quantum optics and communications.
“We thought, why not use what we developed for quantum purposes and use it for one thing extra classical,” mentioned Haig Atikian, a former graduate pupil and postdoctoral fellow at SEAS and first creator of the paper.
Utilizing this method, which makes use of an ion beam to etch the diamond, the researchers sculpted an array of golf-tee formed columns on the floor on a 3-milimeter by 3-milimeter diamond sheet. The form of the golf tees, large on prime and thin on the underside, makes the floor of the diamond 98.9% reflective.
“You may make reflectors which might be 99.999% reflective however these have 10-20 layers, which is ok for low energy laser however definitely would not have the ability to stand up to excessive powers,” mentioned Neil Sinclair, a analysis scientist at SEAS and co-author of the paper.
To check the mirror with a high-power laser, the staff turned to collaborators on the Pennsylvania State College Utilized Analysis Laboratory, a Division of Protection designated U.S. Navy College Affiliated Analysis Heart.
There, in a specifically designed room that’s locked to forestall harmful ranges of laser gentle from seeping out and blinding or burning these within the adjoining room, the researchers put their mirror in entrance of a 10-kilowatt laser, robust sufficient to burn via metal.
The mirror emerged unscathed.
“The promoting level with this analysis is that we had a 10-kilowatt laser centered down right into a 750-micron spot on a 3-by-3-millimeter diamond, which is a variety of power centered down on a really small spot, and we did not burn it,” mentioned Atikian. “That is essential as a result of as laser techniques turn out to be an increasing number of energy hungry, it’s worthwhile to give you inventive methods to make the optical elements extra strong.”
Sooner or later, the researchers envision these mirrors getting used for protection purposes, semiconductor manufacturing, industrial manufacturing, and deep area communications. The method is also utilized in cheaper supplies, corresponding to fused silica.
Harvard OTD has protected the mental property related to this venture and is exploring the commercialization alternatives.
The analysis was co-authored by Pawel Latawiec, Xiao Xiong, Srujan Meesala, Scarlett Gauthier, Daniel Wintz, Joseph Randi, David Bernot, Sage DeFrances, Jeffrey Thomas, Michael Roman, Sean Durrant and Federico Capasso, the Robert L. Wallace Professor of Utilized Physics and Vinton Hayes Senior Analysis Fellow in Electrical Engineering at SEAS.
This analysis was carried out partially on the Heart for Nanoscale Methods (CNS), a member of the Nationwide Nanotechnology Coordinated Infrastructure Community (NNCI), which is supported by the Nationwide Science Basis below NSF award no. 1541959. It was supported partially by the Air Power Workplace of Scientific Analysis (MURI, grant FA9550-14-1-0389), the Protection Superior Analysis Initiatives Company (DARPA, W31P4Q-15-1-0013), STC Heart for Built-in Quantum Supplies and NSF Grant No. DMR-1231319.