In optics, the era of glass lenses may be waning.
In recent years, physicists and engineers have been designing, constructing and testing different types of ultrathin materials that could replace the thick glass lenses used today in cameras and imaging systems. Critically, these engineered lenses—known as metalenses—are not made of glass. Instead, they consist of materials constructed atthenano scale into arrays of columns or fin-like structures. These formations can interact with incoming light, directing it toward a single focal point for imaging purposes.
But even though metalenses are much thinner than glass lenses, they still rely on "high aspect ratio" structures, in which the column or fin-like structures are much taller than they are wide, making them prone to collapsing and falling over. Furthermore, these structures have always been near the wavelength of light they'reinteractingwith in thickness—until now.
In a paper published Oct. 8 in the journal Nano Letters, a team from the University of Washington and the National Tsing Hua University in Taiwan announced that it has constructed functional metalenses that are one-tenth to one-half the thickness of the wavelengths of light that they focus. Their metalenses, which were constructed out of layered 2-D materials, were as thin as 190 nanometers—less than 1/100,000ths of an inch thick.
"This is the first time that someone has shown that it is possible to create a metalens out of 2-D materials," said senior and co-corresponding author Arka Majumdar, a UW assistant professor of physics and of electrical and computer engineering.