Materials’ properties exist in a continuous balance—tweaking one aspect leads to a corresponding change in another. Engineers play a constant game of balancing one characteristic against another in the push to make devices more powerful, smaller, and more energy efficient. A team of electrical engineers at Penn State have found a way to bypass some of this effect by simultaneously controlling diverse optical properties of dielectric waveguides by utilizing a two-layer coating—each layer with a near-zero thickness and weight.
“Imagine the water faucet in your home, which is an essential everyday device,” said Douglas H. Werner, John L. and Genevieve H. McCain Chair Professor of Electrical Engineering. “Without pipes to carry the water from its source to the faucet, the device is worthless. It is the same with ‘waveguides.’ They carry electromagnetic or optical signals from the source to the device — an antenna or other microwave, millimeter-wave or terahertz device. Waveguides are an essential component in any electromagnetic or optical system, but they are often overlooked because much of the focus has been on the devices themselves and not the waveguides.”
Metasurface coatings, so thin that it is almost two-dimensional, allow researchers to shrink the diameter of waveguides and control the waveguiding characteristics with unprecedented flexibility.
Werner’s team developed and tested two conformal coatings by judiciously engineering the patterning on the surfaces, one for guiding the signal and one to cloak the waveguide. The coatings are then applied to a Teflon waveguide with the guiding layer touching the Teflon and the cloaking layer on the outside.
Improving the properties of the waveguide to carefully control polarization and other attributes allows the waveguides to be smaller, and alleviating crosstalk allows these smaller waveguides to be more closely bundled. Smaller waveguides more closely bundled could lead to increased miniaturization.
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