Stacked, shaped metal plates form terahertz-focusing lens

March 23, 2016
The approach may be useful for imaging or in terahertz data networks.

Researchers from Brown University (Providence, RI) have developed a lens for focusing terahertz radiation that is made up of an array of stacked metal plates with spaces between them. The lens performs as well or better than existing terahertz lenses, and the architecture used to build the device could set the stage for a range of other terahertz components that don’t currently exist.

The new lens is made from 32 metal plates, each 100 μm thick, with a 1 mm space between each plate. The plates have semicircular notches of different sizes cut out of one edge, such that when stacked horizontally the notches form a spherical indentation on one side of the device.

Using the configuration developed for this new study, the researchers were able to focus a 2-cm-diameter terahertz beam down to a 4 mm spot. The transmission efficiency of the lens was about 80%—significantly better than silicon lenses, which typically have a transmission loss of about 50%, and about the same as lenses made from Teflon.

The new device has some advantages over existing Teflon lenses, however. In particular, by changing the spacing between the plates, the lens can be tuned for specific terahertz wavelengths.

"That can be particularly interesting if you want to image things at one frequency and not at others," says Dan Mittleman, a professor of engineering at Brown. "One of the important things here is that this design offers you a versatility that a simple chunk of plastic with a curved surface doesn’t offer."

The work also suggests that the technique of using spaced metal plates to manipulate terahertz radiation could be useful in making other types of components that currently don’t exist. Since a metallic architecture mimics a dielectric, this material technology is termed "artificial dielectrics."

The same technology could be used, Mendis said, to make a polarizing beamsplitter for terahertz waves. Such a device could be used to implement elementary logic gates for terahertz photonic systems, where the binary logic states are assigned to the two polarization states, forming part of a terahertz data network.

Source: https://news.brown.edu/articles/2016/03/lens

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

How to Tune Servo Systems: Force Control

Oct. 23, 2024
Tuning the servo system to meet or exceed the performance specification can be a troubling task, join our webinar to learn to optimize performance.

Laser Machining: Dynamic Error Reduction via Galvo Compensation

Oct. 23, 2024
A common misconception is that high throughput implies higher speeds, but the real factor that impacts throughput is higher accelerations. Read more here!

Precision Automation Technologies that Minimize Laser Cut Hypotube Manufacturing Risk

Oct. 23, 2024
In this webinar, you will discover the precision automation technologies essential for manufacturing high-quality laser-cut hypotubes. Learn key processes, techniques, and best...

Advanced Laser Processing Techniques for Surgical Robot End Effector Manufacturing

Oct. 23, 2024
For the cutting-edge manufacturers of minimally invasive surgical robots, precision laser processing is the cornerstone for crafting optimal end effectors. Learn about advancements...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!