There is growing excitement around the metals – and for good reason. Metasurfaces allow manufacturers to replace the three or four lenses (often from multiple suppliers) commonly used in complex optical systems with a single flat lens. For example, consider the 3D detection systems that are popular on many consumer devices, such as Face ID used to open an iPhone.
“The great thing about metasurfaces is the ability to manufacture it using existing semiconductor processes,” saidmetaalz (Boston, MA) CEO and co-founder Robert Devlin. “It moves optics to the same semiconductor foundries that make the electronics, resulting in a reduction in complexity.”
Often, reducing the complexity of an optical system means compromising performance. However, the reverse was true with the first commercial implementation for the Harvard-born startup. “We’ve seen improvement in overall performance, including how much light goes where it’s needed at the image sensor,” says Devlin. “And as we move optics into the semiconductor factory, it also serves as a means of supply chain consolidation.”
While numerous companies are working on metal ses,metaalz is the first to announce the commercial deployment of its technology in consumer equipment. The strategic partnership it announced in June 2022 with semiconductor powerhouse STMicroelectronics (ST; Geneva, Switzerland) is replacing multi-element optical systems with themetaalz optics solution (see image).
Metalz’s offering will initially be a central part of ST’s time of flight (ToF) module, known as FlightSense. The ToF offering uses the speed of light to accurately calculate proximity by measuring the time it takes for a photon to travel to a surface and eventually reflect back.
The primary offerings integrating the ST ToF module include smartphones, drones, robots and vehicles.
Future is flat
The fact that Metaals’ technology offers a flat and completely flat design allows the use of a semiconductor factory.
“This is an important distinction because in most optical systems, either the image sensor or the dot pattern projector in the Face ID, the laser source is also flat and planar,” he says. “With curved bulky refractive lenses, you’re trying to go from a curved surface to a flat surface. And because of that mismatch of lenses with the sensor or the illumination source, you need all these extra optics to correct for aberrations coming into the system.” .”
The flatness allows device manufacturers to eliminate the extra objects and make it with just a single metal surface layer. As such, when integrated into modules, the flat optic allows direct integration with the sensor in the longer term. “You can essentially glue the lens and electronics together to make a complete optical module,” he says. “Whereas with the refractive lenses you have to separate them all to achieve the necessary shape and curvature.”
In addition to the consumer applications that are central to the relationship thatmetaalz has with ST, Devlin anticipates opportunities within automotive LiDAR. However, Auto-LiDAR is undeniably more intricate and complex than the LiDAR systems present in today’s smartphones. “As complexity increases, it becomes more difficult to assemble these units with the same performance from module to module,” says Devlin.
In the consumer space, plastic refractive lenses work because the same temperature requirements do not exist. However, in the automotive sector, glass lenses are crucial.
Temperature changes are important because they can change optical properties. “The meta-surface provides stability because we make the materials at over 300 degrees Celsius,” he says.
Using existing semiconductor plants means parts are competitive with plastic refractive lenses, but using solid state materials. For 3D detection,metaalz makes lenses from solid-state materials such as silicon or silicon dioxide. “This is ideal for automotive applications as they have no variation in performance with temperature changes. There is no degradation of the optics.”
As with any innovative offering, the biggest challenge for a new optical technology is always gaining market acceptance. “Fortunately, with this announcement that we are making with ST Micro, we now have market acceptance,” he says. “This year alone, our metallics will be in millions of consumer devices.”
Formetaalz, the other hurdle was testing the mass production process to ensure that lab scale was translated to semiconductor processes. “Today we have production runs on a real semiconductor line in a 300mm foundry, and our technology is still delivering the performance it needs.”
The next challenge, which Devlin openly welcomes, involves exploring additional application possibilities for metasurfaces and then expanding the offering appropriately to meet the need. “For example, we want to take advantage of the meta-surfaces’ ability to completely control the polarization of light,” he says. “While the first generation of products now has that market acceptance, for the first time we are bringing the potential of entirely new sets of information at the consumer scale and consumer price point.”
“The exciting thing about developing meta-surfaces is the ability to grow complex optical modules. It allows it to go from just a few select OEMs to a price point where it can be used in virtually any phone,” says devlin. “We’ve got the first wins, we’re doing this with existing semiconductor processes without the need for a new form of lithography or deposition, and we’re leveraging existing foundries.”