In early 2016, a team led by Capasso, with key contributions by Khorasaninejad, graduate student Rob Devlin, and postdoc Wei Ting Chen, showed that it indeed could be done and done well enough that commercial devices were possible. Capasso filed a report of invention with the Harvard Office of Technology Development and, soon after, the discovery made Science’s cover. Gordon, OTD’s director of business development for physical sciences, stepped in to manage the avalanche of interest.
“I’ve been doing this for far longer than I like to admit but that paper, the invention, and the patent we filed generated far more commercial interest — from companies, entrepreneurs, investors — than any other hard-tech invention I can remember,” said Gordon. “It was exciting and a bit shocking. We met and talked with a lot of people about this work.”
Those people understood then what Capasso had seen more than a decade earlier. Lenses are essential components in a host of devices, focusing and detecting light — both visible and invisible — for applications well beyond imaging, including facial recognition in smartphones and laptops, proximity and gesture detection to enhance responsive functions in automated devices, depth-sensing cameras, environmental awareness in drones and robots, and collision avoidance in self-driving cars.
In many of those devices, space is tight. The stacked elements of plastic or glass in traditional lenses have resisted the true miniaturization that most other components have undergone. They remain among the bulkier components, and a bottleneck in device design.
“I hold up my cellphone and pull out a credit card,” Gordon said, describing how he introduces the technology to potential investors. “There are only two reasons the phone is not as slim as the credit card. One is the camera and the other is the battery. The metalens will help enable the phone to be as slim as a credit card.”
While traditional lenses use curved glass or plastic to bend light and focus an image, a metalens uses a series of tiny pillars on a millimeter-thin wafer. The pillars are smaller than the wavelength of light and transparent to the desired wavelength. The pillars’ shape, the distances between them, and their arrangement on the wafer are varied to bend light as desired.
“The metalens will help enable the phone to be as slim as a credit card.”
— Alan Gordon, Harvard Office of Technology Development
Not long after that Science cover, OTD licensed the technology to a startup, Boston-based Metalenz, founded by Capasso, Devlin, and Bart Riley, a tech entrepreneur with whom that office had previously worked. Now Metalenz’s chief executive, Devlin made a key materials advance in the Capasso lab that greatly improved the lenses’ efficiency. Earlier this year, Metalenz logged its first major sale, with manufacturer STMicroelectronics. STMicro will use metalenses in the company’s “time of flight” modules, which provide 3D sensing in an array of devices and which have previously sold 1.7 billion units. Those units appear in everything from drones to robots to smartphones. Metalenz said in June that it expects its optical components to be in millions of consumer devices this year.
Khorasaninejad, who today is CEO and cofounder of San Francisco-based Leadoptik, called the deal “a very, very strong endorsement from industry,” while Capasso said that the metalens can be made in the same factories as computer chips is potentially “game-changing,” as it unifies two industries: semiconductor manufacturing and lens-making.
“The same planar technology, known as deep ultraviolet lithography, to mass-produce integrated circuits — chips — can be used by the same foundry to make flat optics such as metalenses,” Capasso said. “It means that the entire camera module of a cellphone or laptop will eventually be manufactured in one sweep, including the metalens and the sensor.”
‘Can you get rid of the lens?’
Capasso came to Harvard in 2003 after a career at Bell Labs, where, in 1994, he and colleagues invented and developed the quantum cascade laser, currently being commercialized in devices for chemical sensing and spectroscopy.
Capasso traced the development of the metalens to a conversation he had more than a decade ago with Jim Anderson, the Philip S. Weld Professor of Atmospheric Chemistry. The two had been discussing putting a quantum cascade laser on a drone that Anderson wanted to use to detect certain chemicals in the atmosphere, but there wasn’t enough room. That was in part because of the bulky optical elements needed for focusing. Anderson got to the heart of the problem.
“He said, ‘Can you get rid of the lens?’” Capasso recalled. “My first reaction was, ‘What the hell is he talking about?’ But then I said, ‘No, wait a moment.’”
Capasso started to brainstorm the idea with a couple of students in his group. Starting in 2007 or 2008, they began to focus on the scientific question of whether it was possible to bend light in an entirely flat device.