Photonics research at the University at Buffalo may lead to more efficient photovoltaic cells, improved radar and stealth technology, and even a new way to recycle waste heat generated by machines into energy.
The work, “Broadband absorption engineering of hyperbolic metafilm patterns” was published 28 March in the journal Scientific Reports, explores the use of a nanoscale microchip component called a “multilayered waveguide taper array” that improves the chip’s ability to trap and absorb light.
Unlike current chips, the waveguide tapers (the thimble-shaped structures above) slow and ultimately absorb each frequency of light at different places vertically to catch a “rainbow” of wavelengths, or broadband light.
Each multilayered waveguide taper is made of ultrathin layers of metal, semiconductors and/or insulators. The tapers absorb light in metal dielectric layer pairs, the so-called hyperbolic metamaterial. By adjusting the thickness of the layers and other geometric parameters, the tapers can be tuned to different frequencies including visible, near-infrared, mid-infrared, terahertz and microwaves.
The structure could lead to advancements in an array of fields. For example, there is a relatively new field of advanced computing research called on-chip optical communication. In this field, there is a phenomenon known as crosstalk, in which an optical signal transmitted on one waveguide channel creates an undesired scattering or coupling effect on another waveguide channel. The multilayered waveguide taper structure array could potentially prevent this.
It could also improve thin-film photovoltaic cells, which are a promising because they are less expensive and more flexible that traditional solar cells. The drawback, however, is that they don’t absorb as much light as traditional cells. Because the multilayered waveguide taper structure array can efficiently absorb the visible spectrum, as well as the infrared spectrum, it could potentially boost the amount of energy that thin-film solar cells generate.
The multilayered waveguide taper array could help recycle waste heat generated by power plants and other industrial processes, as well as electronic devices such as televisions, smartphones and laptop computers.
It could even be used as a stealth, or cloaking, material for airplanes, ships and other vehicles to avoid radar, sonar, infrared and other forms of detection.